Sheep & Goat Research Journal. Volume 33, 2019
Sheep & Goat Research Journal. Volume 32, 2017
Author: Kelyn Jacques and F. Baily Norwood
Effects of Weights, Age and Breed Type on Loin Eye Area, Loin Depth, and Backfat Thickness in Replaceme Ewe Lambs
Author: K.A. Cash, B.C. Shanks, J.D. Caldwell, H.D. Naumann, A.L. Bax, L.S. Wilbers, A.T. McKnelly, T.N. Drane, K.L. Basinger, J.K. Clark and H.L. Bartimus
Passive Transfer in Domestic and Bighorn Lambs
Author: M.A. Highland, A.K. Berglund, D.P. Knowles
Sheep & Goat Research Journal. Volume 31, 2016
Ewe productivity is synonymous with annual litter-weight weaned (LWW) per ewe exposed to rams for breeding, and LWW is largely a function of number of lambs born (NLB) and weaned (NLW). Selecting for LWW should increase litter size and numbers of ewe-ram co-twins. Thus, we used historical records to determine whether sex of co-twin affected lifetime productivity of twinborn ewes. United States Sheep Experiment Station (USSES) lambing records (n = 8,650) from 1991 through 1997 were queried to identify twinborn ewes that were reared with their biological dams and retained in the breeding flock (n = 1,628; Columbia, 383; Polypay, 536; Rambouillet, 383; and Targhee, 326). Corresponding records for lifetime-cumulative counts of lambs born (stillborn and live-born) with recorded birth weights and weaned with recordedweaning weights, cumulative weight of lambs weaned, lifetime count of lambing events, and age at first lambing (1 yr, 2 yr, or 3 yr) were evaluated using PROC GLM and PROC MIXED methods. Alpha was set at 0.10. Only the main effects of sex of co-twin, ewe-weaning weight, ewe breed, and ewe-birth year were significant. Per-ewe exposed to rams, but not per-ewe lambing, cumulative-lifetime weaning weight (P = 0.03) and numbers of lambs born (P = 0.07) and weaned (P = 0.04) were greater for ewes with a ram co-twin than for ewes with a ewe co-twin. Sex of co-twin did not affect number of lifetime-lambing events or age at first lambing for ewes exposed (P = 0.14 and P = 0.59, respectively) or ewes lambing (P = 0.67 and P = 0.27, respectively). Ewe-weaning weight affected cumulative-lifetime weaning weights (P = 0.0003), lifetime numbers of lambs born (P = 0.001) and weaned (P = 0.02), and lifetime-lambing events (P = 0.001), but not age at first lambing (P = 0.44) per-ewe exposed. Productivity of Polypay and Rambouillet ewes generally exceeded that of Columbia and Targhee ewes, although breed ranking was not constant among productivity traits of twinborn ewes. Based on the data, we concluded that ewes born co-twin to a ram had an advantage over ewes born co-twin to a ewe. This advantage amounted to 15.55 kg in lifetime litter-weight weaned per-ewe exposed. We believe that sex of co-twin should be evaluated further to determine whether it is a useful environmental adjustment, beyond lamb sex and type of birth and rearing, for lamb weights and traits related to ewe productivity.
Sheep, Production, Efficiency, Reproduction
Transaction records of 286,764 lambs sold in 25,916 lots at the largest sheep and lamb auction in the United States were collected from 2010 through 2014, in order to estimate factors affecting lamb prices. The data set was restricted to those lots where the average weight per lamb was between 40 pounds and 100 pounds. Lots were classified according to type (hair or wool). Type is an indicator of breed that best represents the lot. Wool lambs were primarily Rambouillet. Hair lambs were primarily Dorper. A hedonic price model was used to estimate price differentials for lambs sold at auction in San Angelo, Texas. The fixed effects for type of lamb, year, month, weight class, lot size and 2-way interactions with type were significant sources of variation. The results indicate an overall discount of $3.42 ± $0.33 per hundredweight for hair lambs relative to wool lambs. The discount was largest in 2011 ($30.72 ± $0.51 per hundredweight). In 2012 the price paid for hair lambs was $9.62 ± $0.61 per hundredweight higher than the price paid for wool lambs. The discount relative to wool lambs increased as lamb weights increased. Hair lambs sold for $3.18±$0.83 per hundredweight more than wool lambs in the 40-pound to 50- pound weight class. Wool lambs sold for $9.09 ± $0.68 per hundredweight more than hair lambs in the 90-pound to 100- pound weight class. Prices increased as lot size increased. Wool lambs sold for a larger premium in the larger lot sizes. Wool lambs sold for $8.59 ± $0.39 per hundredweight more than hair lambs when there were 35 or more lambs in the lot. The difference in price between hair lambs and wool lambs varied across years, months, weight class, and lot size.
Hedonics, Hair Sheep, Price Differentials, Lamb Auction, Texas
This study evaluated performance and health parameters associated with gastrointestinal parasite control when lambs and meat-goat kids were finished on a mixed sward of orchardgrass (Dactylis glomerata L.), red clover (Trifolium pratense L.), and white clover (Trifolium repens L.) with and without supplemental whole cottonseed (Gossypium hirsutum; WCS). Overall average daily gain (ADG) for this 90-d period was increased by supplementation with WCS in Suffolk lambs (P < 0.003), Katahdin lambs (P < 0.17) and goat kids (P < 0.10). Fecal egg count (FEC) was variable over the grazing season each year, but was not impacted by supplementation of WCS at 0.5 percent body weight (BW). Katahdin lambs had lower FEC than Suffolk lambs and typically goat kids. Goat kids and Suffolk lambs had lower (P < 0.001) blood albumin and higher (P < 0.001) globulin concentrations than Katahdin lambs. Supplementation with WCS did not improve FAMACHA© scores, but Katahdin lambs consistently had lower (P < 0.001) FAMACHA© scores than Suffolk lambs and goat kids. Goat kids had the highest FAMACHA© scores. Using FAMACHA© as a means to identify Haemonchus contortus-induced anemia resulted in a mean 56-percent reduction in doses of dewormer administered compared to a theoretical monthly dosing of each animal. After the initial administration of dewormer, days to next dosing of dewormer were fewest for goat kids (33 d), followed by Suffolk lambs (67 d), and greatest for Katahdin lambs (77 d). By considering the use of breed groups resistant to or having high resilience to internal parasites and coupling with the use of the FAMACHA© system to determine the need to deworm individual animals, producers can improve livestock performance and reduce overall cost of production.
Lambs, Goat Kids, Breed, Supplementation, Dewormer Doses
Prevalence of gastrointestinal nematodes is a major challenge for goat producers. One approach to combating internal parasites is to utilize the host animal’s natural or acquired resistance to parasites in a selection program. Therefore, our objective was to estimate genetic parameters for parasite resistance, reproduction, and growth traits in a closed line of Kiko (K) × Boer (B) goats divergently selected for internal parasite resistance. Beginning in 2011, 146 mixed-age (1-yr-old to 6-yr-old) B does were assigned to one of two selection lines: a high line (HL) selected for high resistance to internal parasites and a low line (LL) selected for low resistance to internal parasites. Unrelated K bucks, purchased on the basis of parasite resistance, were exposed to each corresponding doe line. Resulting F1 doe progeny were selected based on parasite resistance and were then backcrossed within line to K bucks to produce F2 ¾ K × ¼ B progeny. Fecal egg count (FEC), blood packed cell volume (PCV), and FAMACHA© scores were measured monthly to evaluate impact of Haemonchus contortus parasite load. Genetic parameters were estimated with linear mixed models using restricted maximum-likelihood procedures. Heritability estimates for FEC, PCV, and FAMACHA© score were 0.13, 0.06, and 0.11, respectively and estimates for litter size, birth weight, and weaning weight were 0.23, 0.18, and 0.17, respectively. The genetic correlation between FEC and FAMACHA© was 0.46, while genetic correlations between FEC and PCV and FAMACHA© and PCV were 0.00 and -0.09, respectively. Results indicate that parasite resistance may be lowly heritable, regardless of parasite indicator trait measured, suggesting that selection progress would be possible, yet slow.
Genetic Correlation, Goat, Heritability, Parasite, Resistance
Gastrointestinal nematode parasitism is one of the greatest threats to economic sheep production in the United States. With increased incidences of anthelmintic resistance and constraints of organic production, there is heightened interest in alternative natural dewormers, such as plants containing condensed tannins. Therefore, the objective of this study was to evaluate effects of organic fermented Pinot Noir (PN) grape extract on parasite level and performance in Katahdin lambs. On October 14, 2014, Katahdin ewe and ram lambs (n = 45; 23.13 kg ± 0.60 BW) were stratified by fecal egg count, weight, sex, and were allocated randomly to one of three treatments: 1) an oral dose (10-mL per 4.5 kg of BW) of fermented PN at 7 d (D7) intervals, 2) the same dose of PN at 14 d (D14) intervals, or 3) control (C; 30-mL oral dose of water at 14 d intervals). Condensed tannins were extracted, purified, and standardized from organic PN and were found to have a concentration of 0.20 mg/mL. Lambs were maintained on tall fescue [Lolium arundinaceaum (Schreb.) Darbysh] pasture, with no additional feed for the duration of the 63-d study. Data were analyzed using PROC MIXED of SAS. Two contrast statements were used to compare the mean of C compared with D7 and D14 and the mean of D7 compared with D14. Average daily gain and total weight gain were greater (P = 0.02) from D7 and D14 compared with C. Start, end, and start to end change body condition scores and FAMACHA© scores did not differ (P ≥ 0.05) across treatments. End of study and change from start to end fecal egg counts were greater (P ≤ 0.05) from C compared with D7 and D14. Change in packed cell volume from start of study to end were greater (P = 0.05) from D7 compared with D14. End monocytes and white blood cell counts were less (P = 0.05 and P = 0.03, respectively) from D7 compared with D14. Other blood parameters were similar across treatments. Therefore, fermented grape extract may be an effective organic and sustainable strategy for controlling gastrointestinal nematodes and increasing performance in Katahdin lambs.
Anthelmintic, Condensed Tannin, Lambs, Organic Grape Extract
The objective of this study was to estimate factors affecting auction prices of kid goats at San Angelo, Texas from 2010 to 2015. Transaction records of 395,009 goat kids sold in 38,862 lots were analyzed with a hedonic-price model that included fixed effects for year and month of sale, weight class, and the size of the lot, and random effects for week of sale, nested within year, and residual. From 2010 to 2015 the Texas-goat population decreased, sales volume decreased, and prices increased. The least squares means price estimates per hundredweight were $150.23 ± $2.41 in 2010 and $251.50 ± $2.38 in 2015. Prices were highest in the first three months of the year, $207.82 ± $1.99 per hundredweight and $38.96 ± $2.78 per hundredweight greater (P < 0.01) than prices in the months of July, August, and September, which had the lowest prices of the year, $168.86 ± $1.94 per hundredweight. The highest unit price received occurred in the 50 to 59 pound weight class ($197.95 ± $1.00 per hundredweight) and was significantly greater than prices for all other weight classes (P < 0.01). Lots that included 35 or more kids, received a $9.96 ± $0.47 per hundredweight greater price (P < 0.01) than lots that sold in lots of 1 or 2 kids ($191.76 ± $1.00 vs $181.79 ± $1.08) Significant differences in prices can be captured by producers who market kids early in the year and within the highest priced weight range and in larger lots.
Meat Goats, Auction Prices, Texas, Seasonality, Non-Traditional Markets, Hedonics
Data from 271 Boer-Spanish and Spanish does and their 1,936 kids obtained between 1995 and 2004 in the Edwards Plateau region of West Texas were examined to compare Boer-Spanish and Spanish does for kid production and stayability. The does were progeny of 24 sires, and their kids were progeny of 39 sires. Goats were maintained on native pastures for most of the year and were managed in an annual kidding system. Kids from Spanish and Boer-Spanish does had similar birth weights (3.19 kg ± 0.05 kg), 90-d weaning weights (16.9 kg ± 0.8 kg), and preweaning ADG (151 g ± 3 g). There were no significant differences between Boer-Spanish and Spanish does for litter weight at birth (5.59 kg ± 0.13 kg vs. 5.36 kg ± 0.14 kg, P = 0.12) or at weaning (23.33 kg ± 0.81 kg vs. 23.86 ± 0.91 kg, P = 0.57). Kid birth weight, weaning weight, and preweaning ADG generally increased with age of dam. Litter weight at birth and at weaning increased (P < 0.05)with age of dam. Stayability of Boer-Spanish does tended to be greater than that of Spanish does at 6 years of age (65 percent ± 4 percent vs. 54 percent ± 5 percent P = 0.07) and similar at all other ages (P > 0.2). No significant breed differences were observed for doe reproduction and kid growth through weaning from Spanish and Boer-Spanish goats in Texas.
Boer-Spanish Goat, Spanish Goat, Stayability
Sheep & Goat Research Journal. Volume 30, 2015
The objective of this study was to investigate genetic control of 120-d weaning weight and the probability of lambing at 1 yr of age in Targhee ewe lambs. Records of 5,967 ewe lambs born from 1989 to 2012 and first exposed to rams for breeding at approximately 7 mo of age were analyzed. Records included lamb birth dates, sire, dam, type of birth and rearing, dam age, and weaning weight and, for ewe lambs, the breeding pen and subsequent lambing data. Weaning weight was evaluated as a continuous variable, and lambing data were recorded as a binomial trait, but both traits were analyzed as continuous variables. Fullterm lambs (either born alive or stillborn) were recorded as a lambing success (i.e., 1); failure to produce a full-term lamb was indicated with a 0. The relationship matrix included 14,041 animals and at least four generations of pedigree information, with more generations included for animals born in later years of the study. Heritability estimates were 0.14 ± 0.02 for 120-d weaning weight and 0.15 ± 0.04 for probability of lambing. Phenotypic and genetic correlations between the two traits were 0.18 ± 0.02 and -0.23 ± 0.18, respectively. Weaning weight and the probability of lambing at 1 yr of age are thus expected to respond to selection. Ewe lambs with heavier weaning weights were more likely to lamb at 1 yr of age, but this is an environmental, rather than genetic relationship, and selection for ability to lamb at 1 yr of age may result in a small decrease in genetic merit for weaning weight.
Sheep, Genetics, Growth, Reproduction, Weaning
Incorporating annual forages into an integrated livestock-crop management system may help prolong the grazing season for most livestock-management systems in the Upper Great Plains. The objectives of this study were to determine (1) the differences in sheep performance ADG (average daily gain) among two mixtures of annual forages and mixedgrass pasture grazed during the dormant season, (2) if differences exist in insect biomass among annual forage mixtures and mixed grass, and (3) to document changes in soil chemical and nutrient status under grazed annual-forage production and grazed mixed-grass pastures. One hundred and eight pregnant Rambouillet ewes were stratified by weight and randomly allotted to one of nine paddocks with two treatments and a control (n = 3) for three consecutive years. Treatments include two spring annual forage plantings (AF1 and AF2), and an introduced mixed-grass and forb mixture that served as the control (CON). Grazing occurred continuously for 21d to 22- d during October. Ewe weight gain was increased (P ≤ 0.02) in the annual forage treatments compared to CON, but was similar between annual forage treatments (P ≥ 0.05). Similarly, crude protein was greater (P< 0.01) in annual forage treatments relative to the CON; 11.84, 12.04, and 5.90, respectively. The higher crude protein in annual forage treatments was likely responsible for the observed response in weight gain. Insect biomass was greatest for AF2, intermediate for AF1 and lowest for CON (P ≤ 0.05). Soils analysis generally revealed no treatment differences during the three-year study period (P ≥ 0.05). Our research indicates that annual forages can provide feed with adequate nutritional value to pregnant ewes and may be an option to lengthen the grazing season and delay the onset of supplemental feeding. Insect biomass differed among treatments (P = 0.02), which could have ecological impacts to the surrounding environment due to the important role that insects play in transferring energy within trophic levels. Additional research is needed to further quantify changes occurring in soil nutrients as a result of long-term propagation and grazing of annual forages within an integrated, crop-livestock system in the Northern Great Plains.
Annual Forage, Cover Crop, Insects, Grazing, Sheep, Soil
Many stressors, including social, environmental, physical, and nutritional, are involved with traditional weaning, which may negatively impact animal performance and behavior. Alternative weaning strategies may be a possible solution to minimize these negative effects. Therefore, the objective of this study was to determine the effects of weaning method and time of day on lamb performance and behavior. Over two consecutive years, 190 spring-born Katahdin ram and ewe lambs (n = 93, 26 kg ± 0.47 kg initial BW, 96 d of age, average in year 1; n = 97, 18 kg ± 0.99 kg initial BW, 89 d of age, average in year 2) were separated from their dams, stratified within litter size at weaning and by BW, sex, and age of their dam and allocated randomly in a 2 × 2 factorial design to one of four treatments representing: 1) Fenceline AM; 2) Fenceline PM; 3) Traditional AM; and 4) Traditional PM for a 14-d weaning period. Lamb weights were collected at the beginning (d 0) and 14-d post-weaning. Behavioral measurements were taken for 10 min per pen at 12 h, 24 h, 48 h, and 72 h post-weaning. Weaning and final weight, ADG, and total gain did not differ (P ≥ 0.88) across treatments. Percentage of lambs vocalizing were greater (P = 0.01) from fenceline weaned lambs compared with traditionally weaned lambs. Percentages of animals walking rapidly, running, standing, and lying down did not differ (P ≥ 0.13) across treatments. A time effect was detected (P < 0.01) for percentage of lambs vocalizing. A treatment × time interaction (P = 0.04) was observed for percentage of lambs lying down. Therefore, utilizing alternative weaning strategies may not improve performance by spring-born Katahdin lambs and may have negative effects on lamb behavior.
Behavior, Katahdin, Performance, Weaning
Livestock guardian dogs (LGD) are one of the most effective methods available to reduce depredation on livestock. The purpose of this study was to determine if the presence of LGD changes grazing behavior of domestic sheep in an environment where predators are common. Western white-face ewes (n = 560) with attending lambs were used. Ewes were 32 d and 45 d postpartum and familiar with LGD. Ewes were divided into four groups (n = 140). Within each group, 12 to 18 ewes were randomly selected to be fitted with GPS tracking collars, which were programmed to collect and record the ewe’s location and velocity at 1-s intervals. In random order, each group was assigned to graze with two LGD present for a 2-d trial period and then graze without LGD present for a 2- d trial period or vice versa. A LGD Presence × Day of Trial interaction was detected (P < 0.05). On Day 2 of the trial, ewes grazing with LGD present traveled farther than ewes grazing without LGD present (8,210 ± 571 m vs. 6,797 ± 538 m, respectively; P = 0.04). No other differences were detected. This study demonstrated that ewes grazing with accompanying LGD will travel greater daily distances compared with ewes grazing without LGD accompaniment. As a result of traveling greater distances, ewes may also be exposed to more and varied foraging opportunities.
Behavior, GIS, GPS, Guardian Dog, Predator, Sheep
Gastro-intestinal parasite (GIP) infestation is a major problem in sheep and goats and results in substantial economic losses. We investigated the prevalence of GIP infestation and its effects on the growth traits of bucks (n=416) on performance test in Maryland over a 12- week-test period. Out of the total bucks tested, 53 percent did not receive any deworming treatment (RG: resistance group) whereas 47 percent of bucks received one or more anthelmintic treatments (SG: susceptible group). The RG bucks had higher ADG (54.33 g vs 42.92 g; P < 0.01), higher body condition scores (BCS: 2.42 vs 2.26; P < 0.001) and were less anemic (lower FAMACHA© score (FAM); P < 0.001), but had no difference in Fecal Egg Counts (FEC) than SG bucks. Correlations between start-of-test body weight (BW) with FAM (-0.22, P < 0.0001), and between end-of-test BW with FAM (-0.24; P < 0.0001) were negative. Regression ADG on FAM was negative (-5.99; P < 0.001) indicating that an increase of a unit of FAM score could reduce ADG of bucks by 5.99 g. The probability estimates from logistic regression analyses showed that a unit increase in FAM at the start of test, the z-score (probability of ranking bucks above average category) decreases by -0.23 and for each unit (kg) increase in start-oftest BW, corresponding probability decreases by 0.04. An understanding of the level of GIP infestation, its effects on performance of bucks and their relationships could benefit the goat industry. Only bucks that ranked high for growth performance and that are resistant to GIP should be considered for breeding.
Gastro-intestinal Parasites, Goats, Performance Testing
Effects of photoperiod in winter on puberty and growth were examined in fall-born ewe lambs, 44 Dorset (D) in year 1 and 23 D, 14 Suffolk x D (SD) and 12 Texel x D (TD) in year 2. Lambs were randomized within age, weight, breed and type of birth and rearing, to be exposed to either natural photoperiod (controls) or both natural and supplemental light (evening, ~100 lux at lamb eye-level) to produce a photoperiod of 16 h light:8 h dark for 14 weeks. At completion of supplemental lighting, each treated lamb received an ear implant of melatonin (20 mg s.c.). Lambs were weighed at weaning, light completion and insertion of controlled-internal, drug-releasing devices containing progesterone (CIDR) to synchronize estrus. Serum progesterone was measured at light completion, and one week before and at CIDR insertion. CIDRs were removed and fertile rams introduced for 27 days or 33 days. Pregnancy was determined by transrectal ultrasonography. At light completion, treated ewe lambs had gained 4.7 kg ± 1.6 kg more than controls in year 1 (P < 0.05), but 3.2 kg ± 2.2 kg less in year 2 (P > 0.05). There was a tendency for more treated than control lambs to have progesterone above 0.3 ng/mL one week before or at CIDR insertion (P < 0.10). Estrous response (year 1) and pregnancy rate (56 percent year 1 and 31 percent year 2) did not differ with treatment. At ages tested, photoperiodic manipulation did not hasten puberty or response to progesterone and ram introduction in fall-born ewe lambs.
Ewe Lambs, Photoperiod, Pregnancy, Puberty, Season
Traditional weaning, characterized by abrupt and complete separation of offspring from their dam, is a common management practice utilized by sheep producers; however, animal performance and behavior may be negatively impacted. Fenceline weaning, an alternative method that has been extensively examined and generally accepted to be effective in cattle, may mitigate the negative effects associated with weaning in sheep. Therefore, our objective was to evaluate the effects of traditional compared with fenceline-weaning methods in drylot, on performance and behavior of Katahdin crossbred lambs. Over two consecutive years, 168 Katahdin crossbred ram and ewe lambs (17 kg ± 0.32 kg initial BW; 74 d ± 4.4 d of age) were stratified within litter size by BW, DOB, and sex and were allocated randomly to one of two weaning treatments: 1) traditional (TRAD) or 2) fenceline (FEN). Lamb BW and BCS were taken on d 0, d 14, and d 43 (year 1) or d 45 (year 2) of the study. Behavioral measurements were taken for 10 min at 12 h, 24 h, 48 h, and 72 h post-weaning. Lamb performance and behavior did not differ (P ≥ 0.28) between treatments. A time effect was detected (P < 0.01) for percentage of lambs vocalizing, running, standing, and lying down. A treatment × time interaction (P < 0.01) was detected for percentage of lambs vocalizing with FEN vocalizing more at 12 h compared with all other treatment and time combinations. Therefore, fenceline weaningin drylot may not improve lamb performance and behavior in Katahdin-crossbred lambs.
Behavior, Fenceline, Lambs, Weaning
Sheep & Goat Research Journal. Volume 29, 2014
A high concentration of caseins in milk is a prerequisite for a high cheese yield. Over 70 percent of Norwegian Landrace goats have been shown to have a mutation that reduces or removes the ability to produce αS1-casein (αS1-CN), with a subsequent lower cheese yield as a consequence. Swedish Landrace goats are closely related to Norwegian goats, so it is very likely that Swedish goats carry the gene for zero-synthesis of αS1-CN. The objective of this study was to survey the Swedish goat population in order to estimate the frequency of Swedish goats producing low amounts of αS1-CN. By use of capillary zone electrophoresis, milk samples from 283 goats from ten different geographical regions of Sweden were analysed. Sixty-five percent of goats were found to produce low or no concentrations of αS1-CN. Only 12 percent of the dairy goats showed a high expression of this protein.
Swedish Goats, αS1-Casein, Capillary Zone Electrophoresis
The objective of this study was to investigate the effects of sex, breed, docked-tail length, and the expression of the callipyge phenotype on the incidence of rectal prolapse in lambs. To test whether these factors influence rectal prolapse in a controlled feedlot environment, lambs (n = 382) representing both sexes and four breed types were assigned randomly to one of three docking treatments: 1) tail removed as close to the body as possible (short-docked, n = 139); 2) tail removed midway between the attachment of the tail to the body and the caudal folds to the tail (mediumdocked, n = 124); and 3) tail removed at the attachment of the caudal folds to the tail (long-docked, n = 119). Incorporating the callipyge phenotype into the study design assessed the effect of enhanced muscle development on rectal prolapse. The overall incidence of rectal prolapse in this study was 2.1 percent. Ewe lambs were no more likely to experience prolapses than male lambs (P > 0.09). Seven of the eight (87 percent; P < 0.01) lambs that prolapsed were hair sheep. No lambs expressing the callipyge phenotype prolapsed. There was no difference (P > 0.05) in rectal prolapse occurrence among the three docking treatments. In this study sex, tail dock length, and muscling did not appear to contribute to rectal prolapse in lambs. However, there may be an over-looked genetic component that influences the occurrence of prolapses in response to the practice of docking.
Lambs; Docking; Sheep; Rectal Prolapse; Tail Length
Rotational grazing has increased in popularity; however, this management practice has not been evaluated thoroughly with Katahdin hair sheep. Our objective was to evaluate the effects of continuous or rotational grazing on performance by yearling Katahdin ewes grazing endophyte-infected, tall fescue [Lolium arundinaceum (Schreb.) Darbysh; E+] in late spring through summer. Over two consecutive years, a total of 50 yearling Katahdin ewes were stratified by BW and BCS and allocated randomly to one of five, 0.4-ha E+ pastures on May 5, 2011 and May 7, 2012. Treatments consisted of: 1) continuous (Cont) or 2) 4- cell rotation (4R). Basal cover and forage quality and quantity did not differ (P . 0.19) between treatments. A sampling date effect (P . 0.01) was detected for forage quality and quantity. Grazing d, beginning, end of breeding, and end of the grazing period BW, FAMACHA scores, ADG, total gain, number of lambs/ewe exposed, and lamb birth weight did not differ (P . 0.12) between treatments. Ewe BW and BCS change during the breeding season did not differ (P . 0.17) between treatments. Beginning breeding BCS tended (P = 0.10) to be greater for Cont compared with 4R, but end BCS did not differ (P = 0.45) between treatments. Pregnancy rates and frequency of multiple births were greater (P . 0.04) from 4R compared with Cont. Therefore, utilizing a 4-cell, rotational-grazing system for yearling Katahdin ewes grazing E+ in late spring through summer may improve pregnancy rates and multiple births. However, further studies are warranted.
Key words: Continuous Grazing, Forage Quality and Quantity, Performance, Tall Fescue, Yearling Katahdin Ewes
The objective of this research was to determine the influence of diet particle size and lasalocid on growth and feed intake, carcass characteristics, and N balance in feedlot lambs. One hundred sixty crossbred (Suffolk x Rambouillet) lambs (31.2 kg ± 0.09 kg) were stratified by weight and sex in a completely random design and allotted to one of 16 pens (n = 4). Lambs were fed a basal feedlot diet consisting of 80 percent corn and 20 percent market lamb pellet ad libitum (AF basis). Diets were whole corn with lasalocid (WCL), whole corn without lasalocid (WCNL), ground corn with lasalocid (GCL), or ground corn without lasalocid (GCNL). Lambs were harvested following the 112 d feeding trial (69.7 kg ± 0.74 kg BW) and carcass data were collected at a commercial abattoir. Final BW, DM offered, G:F, mortality, and the majority of carcass traits were not affected by diets (P ≥ 0.06). Lasalocid-fed lambs had an increase in HCW (P = 0.05). Additionally, there was an interaction of particle size and use of ionophores for ADG (P = 0.05), loin eye area (P < 0.001), and percentage of boneless closely trimmed retail cuts (%BCTRC; P = 0.004). Loin eye area was greatest (P < 0.05) for WCL and GCNL. A second study was conducted utilizing the same diets to evaluate N balance in 16 crossbred wethers (Suffolk x Rambouillet; 40 kg ± 1.7 kg BW; n = 4). Nitrogen balance was not affected by diet (P = 0.22). Our results indicate that HCW in lambs fed lasalocid was increased by 3 percent, while particle size had no major impact on growth, feed intake, carcass traits, or N digestibility.
Carcass, Growth, Ionophores, Lasalocid, Particle Size, Sheep
There appears to be increased consumer demand for grass-finished products and elevated preference for locally produced foods, including lamb. Therefore, our objective was to evaluate consumer acceptability and shear force of retail domestic, grain-finished (D); imported New Zealand, grass-finished (N); and Missouri-produced, grass-finished (M) lamb racks. Lamb racks (n = 58) were purchased from three different retailers located in Missouri. After purchase, racks were stored frozen at -20°C for three weeks. Racks were then thawed at room temperature and mechanically fabricated into 2.5-cm thick chops, which were trimmed to include only the longissimus muscle (LM). Three LM chops from each rack were stored at 2°C for two days prior to consumer panel evaluation and two chops from each rack were refrozen (-20°C) for Warner-Bratzler shear-force determination. Consumer panel LM chops were cooked to an internal temperature of 71.1°C on a gas grill and panelists (n = 98) were asked to fill out demographic information and evaluate each sample on a ninepoint hedonic scale (1 = dislike extremely to 9 = like extremely) for each consumer-acceptability trait. Overall acceptability, tenderness, juiciness, flavor, and leanness-acceptability ratings were greater (P < 0.05) from D compared to M and N. Racks from M and N were rated leaner (P < 0.05) than D. All consumer acceptability attributes were similar (P > 0.05) between M and N. Shear-force values from D and N were lower (P < 0.05) compared to M. Therefore, racks from grass-finished lamb may not be evaluated as favorably as racks from grain-finished lamb, but depending on origin, may be as tender as racks from domestic, grain-finished lamb.
Key Words: Grass-Finished, Domestic Grain-Finished, Lamb Rack, Consumer Acceptability
Bitterweed (Hymenoxys odorata DC) toxicity is a major cause of death losses in Rambouillet sheep. This study compared the susceptibility of two breeds [Rambouillet and Dorper × Barbados Blackbelly (DBB)], of wool and hair sheep lambs to bitterweed toxicosis; and the potential for cull onions (Allium cepa) to mitigate bitterweed toxicity. Onions contain high concentrations of naturally occurring thiols, thus offering the opportunity for the introduction of a diversionary substrate for the principle toxin, hymenoxyn, in a palatable feedsource. Weanling Rambouillet (n = 12; LS means ± SE = 22.7 kg ± 1.3 kg BW) and DBB (n = 12; LS means ± SE = 22.5 kg ± 0.8 kg BW) ram lambs were assigned randomly to one of four treatments: 0 percent (control), 25 percent, 50 percent, and 75 percent onions in diet (DM basis). The remainder of the isonitrogenous diets consisted of alfalfa pellets to provide 32 g DM/kg BW per day. Animals were group-fed onions for a 10-d preconditioning period, then penned and fed individually for study.Individual onion feeding commenced on d 0 and continued through d 7. On d 3 of onion feeding, lambs were dosed with an aqueous slurry of dried bitterweed (0.25 percent of BW, DM-basis) daily through d 7. Blood samples were taken on d 3 and d 8 and analyzed for serum constituents indicating onion- or bitterweed-induced pathologies, respectively. Dry-matter intake and percentage of feed refusals were measured daily. In response to onion diets, serum urea nitrogen (SUN) decreased linearly (P < 0.001). Concentrations of albumin, aspartate aminotransferase (AST), glucose, hematocrit and total serum protein (TSP) were greater in DBB lambs than in Rambouillet lambs (P < 0.01), but remained clinically normal. The bitterweed challenge elicited a breed effect (P < 0.05) for serum measurements reflective of bitterweed toxicity; bilirubin, gamma-glutamyltransferase (GGT) and AST concentrations were greater (P ≤ 0.001) for DBBs than for Rambouillets. The AST, bilirubin, creatinine, GGT, and SUN were clinically high for all treatments, including controls, indicating acute toxicity. Feed refusals did not differ among treatments or by breed (P > 0.10). In this study, dietary onions did not prevent pathological changes in serum chemistries following bitterweed dosing, and had no influence on feed refusals. Both breeds exhibited clinical signs of bitterweed toxicosis, with DBB sheep exhibiting greater abnormal deviation in serum chemistries than Rambouillets.
Key Words: Bitterweed, Onions, Hair Sheep, Dorper, Barbados Blackbelly, Rambouillet, Toxicosis
Breeding objectives and selection indexes are necessary to support comprehensive genetic-improvement programs. This study used off-test body weights (OTBW) or chilled-carcass weights (CCW), ultrasonic measurements of fat depth (USFD, mm), and predicted-ultrasound, loin-muscle depths (USLMD, mm) from 456 wether lambs to predict carcass value and link predictions to estimated breeding values (EBV) of terminal sires. Carcasses were processed by closely trimming high-value cuts (rack, loin, leg, and sirloin), and carcass value (TrCVal) was determined for each carcass. Increasing OTBW had positive effects on carcass value but did not affect dressing percentage (DP). Increasing USFD increased CCW and DP but decreased TrCVal. Increasing USLMD had positive effects on CCW, DP, and TCVal. The EBV for postweaning weight (PWWT), USFD, and USLMD of average and elite Suffolk rams were compared to develop breeding objectives for lambs harvested at a constant time on feed, harvest weight, or harvest fatness, and for a scenario with larger-than-current-price premiums for leanness and muscling. At constant harvest weights, the breeding objective was I2 = 1.2 EBVPWWT – EBVUSFD + 0.8 EBVUSLMD, but changed to I4 = 0.3 EBVPWWT – EBVUSFD + 0.4 EBVUSLMD if carcass price was strongly influenced by leanness and muscling. Genetic correlations among indexes exceeded 0.85. Index I4 was strongly correlated with the Australian LAMBPLAN Carcass Plus index, indicating that selection on Carcass Plus would be effective under U.S. conditions. All indexes were dominated by PWWT EBV. Effects of increasing muscling were substantial, but changing USFD EBV had only modest effects.
Key Words: Breeding Objectives, Carcass Value, Genetic Evaluation, Sheep
Seventy two Polypay crossbred lambs (BW 34.3 ± 0.75 kg) were used in a complete randomized design to determine the effect of supplemental fat source on growth performance and carcass characteristics over a 70-d feeding period. Lambs were stratified by weight and sex and assigned to 12 pens (3 wethers and 3 ewes per pen). Pens were assigned randomly to one of three dietary treatments consisting of 40 percent corn stover, 4 percent soy hulls, 2.4 percent supplement and one of the following treatment combinations: 1) 34 percent low-fat dried distillers grains (CON), 2) 34 percent conventional dried distillers grains plus solubles (DIST), 3) 34.6 percent low-fat dried distillers grains plus 1.85 percent raw corn oil (OIL). DIST and OIL diets were formulated to be iso-lipid. Lambs were allowed ad libitum access to feed and water. On d 21, d 42, and d 63 feeders were emptied and residual feed was weighed, recorded, and sampled. Initial and final BW were determined as the average of weights on d -1 and d 0 (initiation of feeding) and d 69 and d 70, respectively. Three intermediate weights were recorded on d 21, d 43, and d 63 to monitor growth performance. At the conclusion of the feeding period, four lambs were harvested from each pen and carcass data were collected. Cumulative DMI, ADG, G:F, and final BW were similar (P > 0.24) for lambs fed the fatsupplemented diets and the CON diet, however, lambs fed the DIST diet had greater (P < 0.01) cumulative DMI, ADG, G:F, and final BW compared to the OIL diet. Supplementation with corn oil tended (P = 0.06) to decrease HCW compared to supplementation with DDGS, but there were no differences between the CON diet and fatsupplemented diets (P = 0.44). Dressing percentage; backfat thickness; LM area; body wall thickness; USDA-yield grade, and boneless, closely trimmed retail cuts were not affected by fat supplementation or source of fat (P > 0.20). However, lambs were fed a higher energy diet for the last two weeks of the trial to meet target finished-weight goals.
Key Words: Fat, Lambs, Growth, Dried Distillers Plus Solubles
Sheep & Goat Research Journal. Volume 28, 2013
Early and accurate identification of pregnancy and lambing rate provides sheep producers many advantages for management decisions that improve flock productivity. The objective of this study was to investigate the efficacy of a commercial pregnancy-specific protein B (PSPB) ELISA assay to predict pregnancy and lambing rate in sheep. On days 20, 25, 30, 40, and 60 postbreeding, blood samples were collected from Columbia and Hampshire ewes. Dorset and Katahdin ewes were sampled 49, 63, and 77 days post ram introduction. Lambing records were used to verify date of conception. Samples were processed using the quantitative BioPRYN®assay for sheep and goat. BioPRYN® classification was 99 percent accurate for pregnant ewes tested after the first month of gestation (i.e., greater than 30 days). For ewes that did not lamb, 90 percent were classified as open and the remaining 10 percent were either misdiagnosed or lost the pregnancy prior to parturition. Ewes carrying multiple pregnancies had greater serum PSPB concentrations than singleton pregnancies from d 40 to d 69 of pregnancy. Effect of breed was detected for serum concentrations of PSPB from d 40 to d 79 of pregnancy. This research indicates that the Bio-PRYN® test is an effective tool to identify pregnancy in sheep. This test could provide estimates of lambing rates; however, variation in PSPB concentrations due to stage of pregnancy and breed of sheep must be factored into this analysis.
Pregnancy-Specific Protein B, Sheep, Fetal Age, Pregnancy Rate, Breed
Growth and Performance of Meat Goat Kids from Two Seasons of Birth in Kentucky
Little information is available on the impact of season of kidding on growth and performance of meat-goat kids. However, seasonal market trends have many producers in the southeastern United States kidding in the late fall and winter, when animals must be supplemented to meet nutritional needs. Because of this, a study was designed with the objectives being to evaluate the effect of season of birth and ther factors on kid survival to weaning and performance from birth to weaning in meat-goat kids. One hundred and twenty commercial-meat-type does were used in this study. The does were bred for kidding either in the fall (October, November, and December) or spring (March, April, and May) seasons. Data collected included birth weight, birth type, sex, 60 d weight, and 90 d weight. Season of birth had a significant effect on birth (P < 0.0001) and 90 d wt (P = 0.0063), and ADG between 60 d and 90 d (P = 0.0003), with fall-born kids being heavier and having higher daily gains. The interaction between year and birth type was significant (P = 0.0004) for birth weight and the sex by birth/rearing type interaction was significant for 60-d wt (P = 0.0003) and ADG to 60 d (P = 0.0002). These data indicate that season of birth has an impact on some performance traits in meat goat kids. These differences can impact profitability and need to be studied in more detail to determine specific impacts on productivity and profitability of the meat goat industry.
Key Words: Meat Goat, Season of Birth, Kid Performance, Preweaning Growth.
Accuracy of Ultrasonographic Diagnosis of Sex and Effect of Sex and Birth Type on Biparietal Diameter of Saanen Goat Fetuses
The effects of sex and birth type on biparietal diameter (BPD) were examined from 6th to 14th weeks of gestation in 29 pregnant Saanen does by ultrasonography and after birth by observing the kids directly. Fifteen does delivered singles, 13 had twins and one goat had quadruplet males. Twelve of the twins were male and 13 were female; 7 singles were male and 8 were female. In twin pregnancies, the most accurate period for diagnosis of sex of the fetus by observation of the position of the genital tubercle was the 9th week of gestation. However in singles, two errors (13 percent) were made at the 9th week. Twoway anova analysis revealed that birth type did not affect BPD of Saanen goat fetuses, and sexes did not differ until the 14th week (P < 0.05). Even then, the difference was too small to be useful to predict the sex of the offspring. Chisquare test was applied to compare the success rates of ultrasonography for prediction of fetal sex in different weeks of gestation. Ratio for success of sex determination by ultrasonography was greater from the 9th week of gestation compared with earlier periods in twin pregnancies (P < 0.001). On the other hand, there were no significant differences among gestation weeks in terms of ratio for success of sex determination by ultrasonography in single pregnancies (P > 0.05). Thus it is concluded that sex of the fetus can be diagnosed directly at the 9th week, but one cannot establish the sex of the fetuses by using only ultrasonographic measurements of BPD in either twin or single pregnancies in Saanen goats.
Keywords: Biparietal Diameter, Birth Type, Saanen
Tail Length at Docking and Weaning of Lambs
This study was conducted with crossbred lambs (n = 109 female and 120 male) to measure tail length at docking and weaning and to determine the change in length between docking and weaning. Lambs were born in April and weaned at approximately 125 d of age. Within 24 h after birth, lambs were weighed and ear tagged, and rubber rings were applied to dock tails. Rings were applied just past the distal end of the caudal folds of the tail, which is just beyond where the folds attached to the tail. Time of rubber ring application was considered time of docking. Using a specially designed device, tail lengths were measured immediately after rubber ring application and at weaning. Lambs were weighed at weaning. Sex and breed type affected (P < 0.005) BW at docking and weaning; male and black-faced × whitefaced lambs were heavier than female and white-faced × white-faced lambs. At docking, neither sex, breed type, nor the sex × breed-type interaction affected actual tail length or tail length adjusted for BW, although BW at docking was a significant (P < 0.0001) covariate. At weaning, the sex × breed type interaction affected (P < 0.002) actual tail length, which was greater (P < 0.002) for male, black-faced × white-faced lambs than for lambs of the other sexbreed-type classifications. At weaning, sex and sex × breed type affected (P < 0.01) tail length adjusted for the covariate BW at weaning. Breed type affected (P < 0.006) the change in actual tail length between docking and weaning (white-faced × white-faced, 2.4 cm, vs. black-faced × white-faced lambs, 2.7 cm). The data indicate clearly that tail length increased between docking and weaning.
Key words: Lambs, Tail Docking, Tail Growth
Technical Note: Effects of Supplementation of Expired Human Foodstuffs on Intake and Digestion of Wethers Fed a Base…
There is potential for expired human foodstuffs to be used as an energy supplement for livestock. Sixteen crossbred wether lambs were used in a completely randomized design to investigate the effects of feeding supplemental expired human foodstuffs on DM, OM, ADF and NDF digestibility, and intake. Wethers were fed (DM basis) isocaloric amounts of the following treatments: whole barley served as the control (BAR: 0.20 kg·wether-1·d-1), potato chips (PC: 0.15 kg·wether-1·d-1), macaroni (MAC: 0.21 kg·wether-1·d-1), and donuts (DON: 0.15 kg·wether-1·d-1). Wethers were fed 0.60 kg·wether-1·d-1 alfalfa/barley pellets and allowed ad libitum access to chopped hay. Wethers were placed in confinement crates for a 7-d acclimation period, fitted with fecal bags on d 0 and fed twice daily. Following acclimation, daily intakes, refusals, and fecal outputs were used to determine DM, OM, fiber digestibility and intake. Measures of intake and digestibility did not differ (P > 0.23) among treatments. It is concluded that these expired human foodstuffs have the potential to be used in ruminant diets as an alternative to traditional feedstuffs.
Key Words: Digestibility, Expired Foods, Intake.
Sheep & Goat Research Journal. Volume 27, 2012
Effects of Supplemental Dried Distillers Grains or Soybean Hulls on Growth and Internal Parasites Status of Grazing Lambs
The objectives of this study were to determine the effects of supplementation of grazing lambs with dried distillers grains with solubles (DDGS) or soybean hulls (SBH) on growth rate and nematode-parasite status. Over the course of four experiments in consecutive years, 312 lambs were grazed on the same four or six paddocks. Grazing lambs were allotted to one of three supplementation treatments: 1) control, no supplementation (CONT), 2) DDGS, or 3) SBH (Exp. 3 and 4 only). Supplemental DDGS improved (P < 0.01) ADG when compared to CONT, and SBH supplemented lambs were intermediate. An analysis comparing CONT vs. DDGS supplementation across all four experiments revealed a reduction in anthelmintic-treatment rate required when DDGS were supplemented (81.2 percent vs. 30.1 percent for CONT and DDGS, respectively; P < 0.01). Measures of FAMACHA© score, packed-cell volume (PCV), and fecal-egg count (FEC) were recorded in weeks 3, 5, and 10. An analysis comparing just CONT and DDGS supplementation across all four experiments revealed that DDGS supplementation reduced (P < 0.01) FAMACHA score in weeks 3, 5, and 10, but only reduced FEC in week 3 compared to CONT lambs. Supplementation of grazing lambs with DDGS in this study allowed for increased growth, reduced anthelmintic-treatment rate, and reduced risk of becoming anemic as a result of internal parasites.
Key Words: Distillers Grains, Grazing, Lambs, Parasite, Soybean Hulls, Supplementation
Performance of Meat Goats Control-Grazed on Winter Annual Grasses
The performance of yearling replacement does and castrated male goats (Capra hircus hircus) controlledgrazed on cereal rye (CR; Secale cereale L.), annual ryegrass (RG; Lolium multiflorum L.) and triticale (TT; Triticosecale rimpaui) was evaluated during a 3-year study. Each year, 54 Boer and Boer-cross goats (avg initial age and BW: 8 mo to 10 mo and 30.4 kg, respectively) were assigned to nine plots (0.19 ha each) each containing six “tester” goats. Additional goats (put and take) were used to control forage growth. Forage species had no effect on ADG; however, castrated males gained more weight than does in year 2 (139 g/d vs. 94 g/d; P < 0.003) and during period 2 in year 3 (224 g/d vs. 146 g/d; P < 0.0004). Gain per ha was greater for RG than CR and TT (year 1: 514, 311, 293 kg, P < 0.001; year 2: 237, 144, 184 kg, P < 0.004; year 3: 528, 268, 149 kg, P < 0.004). In year 3, pH of ruminal fluid, ruminal ammonia and chilled-carcass yield from castrated males grazing RG, CR and TT was similar (avg: 6.67, 25.7 mg/dL and 51.3 percent, respectively), whereas plasma-urea nitrogen (16.4, 21.9, 24.1 mg/dL; P < 0.024), ruminal acetate (62.0, 60.7, 57.7 mM/100mM; P < 0.017), propionate (22.0, 25.2, 27.0 mM/100mM; P < 0.006) and acetate:propionate (2.83, 2.43, 2.22; P < 0.017) differed among forage species. Results indicated that yearling goats achieved satisfactory BW gains when fed only on these forages under controlled, rotational-grazing management, but that RG resulted in significantly greater BW gains per hectare.
Key Words: Annual Ryegrass, Cereal Rye, Meat Goat, Performance, Triticale
Efficacy Of Garlic Juice, Copper Oxide Wire Particles, And Anthelmintics To Control Gastrointestinal Nematodes In Goates
Resistance of gastrointestinal nematodes (GIN) to anthelmintics and a need for nonchemical control of GIN necessitates investigation of alternative control methods. This study examined the efficacy of garlic juice (99.5 percent pure) (G), copper oxide wire particles (COWP), levamisole (L), moxidectin (M), a combination treatment of COWP and G (CG), and no treatment (C) for GIN control in lactating Boer x Kiko does. Treatments were administered at d 0 and the G treatment was repeated every 7 d throughout the 28 d study. Mixed-model procedures for repeated measures were used to evaluate the effect of treatment and date of sampling on fecal-egg counts (FEC), and percentpacked-cell volume (PCV). Larval cultures from fecal samples at d 0 contained H. contortus, but Telodorsagia and Trichostrongylus were the predominant parasites. There was no difference (P > 0.05) in FEC or PCV of does due to GIN-control method. The PCV was greater (P < 0.05) at d 0 (31.2 percent ± 0.7 percent) when compared to d 7 (29.1 percent ± 0.7 percent), d 14 (28.7 percent ± 1.1 percent), and d 21 (28.8 percent ± 0.8 percent). The PCV at d 28 (23.5 percent ± 0.9 percent) was lower (P < 0.001) than all other sampling d. The FEC did not differ (P > 0.05) at d 0 (756 eggs/g ± 414 eggs/g), d 7 (1349 eggs/g ± 448 eggs/g), and d 14 (1782 eggs/g ± 436 eggs/g). The FEC at d 21 (2259 eggs/g ± 464 eggs/g) was trending (P = 0.08) higher as compared to d 0. The FEC at d 28 (3935 eggs/g ± 449 eggs/g) was greater (P < 0.05) than FEC at all other sampling d. Trichostrongylus and Telodorsagia were the primary GIN species and not H. contortus as is often assumed at the research and farm level. These data support determining which GIN species are present in a goat herd at various times of the year and applying an internal-parasite-management protocol accordingly. Treatments used in this study were not effective in controlling any of the GIN species present.
Key Words: Goat, Parasitism, Garlic, Copper Wire, Anthelmintic
Effectiveness of Theobromine and Caffeine Mixtures in Coyote Lure Operative Devices as a Predacide: A Simulated Field Study
Predators are capable of causing damage to domestic livestock throughout North America. Lethal responses for managing livestock depredations may include the use of sodium cyanide in M-44 devices. Currently, several states have banned the use of M-44s and several other states are forecast to ban these devices. Therefore, additional tools are being sought to expand the repertoire of options available for managing coyote depredations on domestic livestock. We evaluated the use of a theobromine:caffeine mixture delivered within a Coyote Lure Operative Device (CLOD) as an additional predacide for coyotes (Canis latrans). Results from six trials involving 38 captive coyotes were ambiguous. Issues related to the attractiveness of the CLOD, palatability of the compound, and absorption of the theobromine:caffeine mixture produced mortality levels below the desired >90-percent-mortality rate deemed adequate for laboratory efficacy study to the United States Environmental Protection Agency (EPA) registration and operational use. While many coyotes died from consumption of the theobromine:caffeine mixture, several coyotes recovered with symptoms of poisoning disappearing within 12 hours in those animals that survived exposure to the toxicant. Several issues related to palatability of the mixture and compound delivery, as well as coyote behavior, sensory abilities, and physiology, indicated the use of a theobromine: caffeine mixture in a CLOD may not be an effective method for managing coyote depredations on domestic livestock.
Key Words: Caffeine, Canis latrans, CLOD, Coyote, Mortality, Theobromine
Post-Natal Skin Follicle Development in The Raieni Cashmere Goat
One hundred eighty (180) skin samples were taken from the mid-right side of 30 Raieni Cashmere goat male and female kids at 1 mo, 1.5 mo, 2 mo, 2.5 mo, 3 mo and 3.5 mo of age. Numbers of primary and secondary skin follicles were determined for each sample. Numbers of secondary follicles increased until 3 mo of age, but numbers of primary follicles did not change after birth of the kids. The skin-follicle traits were not significantly (P > 0.05) affected by sex, birth type and age of dam.
Key Words: Skin-Follicle Traits, Cashmere Goats, Raieni Cashmere Goats
Research Symposium Utilization of Genomic Information for the Sheep Industry
During the ASI Annual Convention in Scottsdale, Ariz., January 26, 2012, a research symposium Utilization of Genomic Information for the Sheep Industry was co-sponsored by the American Sheep Industry Association (ASI) and the American Sheep and Goat Center (ASGC). The Symposium Program Planning Committee consisted of Paul Rodgers, ASI; Will R. Getz, Fort Valley State University; and Larry R. Miller, ASGC, who also served as Moderator. The symposium was somewhat different from previous ASI research symposia, in that it more comprehensively focused on a single topic, involved speakers from different perspectives and engaged participants in more indepth discussion.
Especially in the past two decades, volumes of new genomic and genetic information have been generated by means of new research approaches, techniques, and tools. This information created a challenge to harness, interpret, and utilize the wealth of new genomic/genetic information by drawing upon disciplines, such as biochemistry, genetics, statistics, computer science, animal breeding, and several other sciences associated with the biology of the animal.
The speakers addressed the symposium topic from the following points of view, reflecting their different expertise and experiences: Genomic Information Available for Use by the Sheep Industry, Noelle E. Cockett, Utah State University; Application of Genomic Information for Improvement of Quantitative Traits, David R. Notter, Virginia Tech University; Utilization and Potential of Estimates of Genetic Value from an Industry Perspective, David L. Thomas, University of Wisconsin-Madison; Utilization from a Producer Perspective, Chase T. Hibbard, sheep producer, Helena, Mont.; and Genetic Selection Specifically Utilized for Evaluating the Introduction of Outside Breeds and Measuring Their Potential, John Helle, sheep producer, Dillon, Mont.
Sheep & Goat Research Journal. Volume 26, 2011
Growth and Carcass Characteristics of Conventionally Raised Lambs Versus Naturally Raised Lambs
This study compared growth and carcass quality of conventionally and naturally raised lambs. The hypothesis tested was conventionally raised lambs would have increased growth, but conventional management would not affect carcass characteristics. Two hundred eighty-eight Rambouillet x blackface (Suffolk and Hampshire) lambs (34.1 kg ± 0.13 kg) were randomly assigned to conventional (CONV) or naturally raised (NAT) treatments (6 pens/treatment; 24 lambs/pen) and fed ad libitum via self feeders for 112 d. The NAT lamb diet was 80 percent corn and 20 percent commercial supplement (DM basis; 87.9 percent TDN and 15.8 percent CP) with decoquinate. The NAT lambs were not given antibiotics or growth promoting implants. Conventionally raised lambs were fed a similar diet, with decoquinate, chlortetracycline, and lasalocid included, and were implanted with 36 mg zeranol on d 28. Lambs were weighed and feed refusals collected every 28 d. Lambs were harvested and carcass data collected 24 h post chill. Overall, CONV lambs had increased ADG (0.35 kg vs 0.33 kg ± 0.006 kg; P = 0.03) and final BW (73.3 kg vs. 71.3 kg ± 0.71 kg; P = 0.07) compared to NAT lambs, but DMI (1.64 kg/d vs 1.58 kg/d ± 0.04 kg/d; P = 0.55) and G:F (0.22 vs 0.21 ± 0.004; P = 0.32) were not different between treatments. Naturally raised lambs had greater rib eye area (P = 0.03), decreased body wall thickness (P = 0.05), and increased percentage boneless, closely trimmed retail cuts (P = 0.05). More CONV lambs prolapsed (8.3 percent vs 0 percent; P = 0.001) which increased mortality (2.8 percent vs 0 percent; P = 0.01). In the current trial, naturally raised lambs had decreased growth, marginal increases in carcass quality, and were less susceptible to prolapse and mortality than conventionally raised lambs.
Key Words: Antibiotic, Carcass Traits, Feedlot Performance, Lamb, Naturally Raised, Zeranol
Effects of Rumen-Protected Arginine Supplementation on Ewe Serum-Amino-Acid Concentration…
The objectives of this research were to determine if rumen-protected arginine supplemented to ewes on d 8 to d 13 of the estrous cycle affected serum-aminoacid concentration, ovarian blood flow, and circulating progesterone. Nineteen multiparous Dorset ewes (63.8 kg ± 1.1 kg initial BW) were individually housed and randomly allocated to one of four rumen-protected arginine treatments: 0 (CON; n = 5), 90 mg/kg BW supplemental arginine (90 ARG; n = 4), 180 mg/kg BW supplemental arginine (180 ARG; n = 5), or 360 mg/kg BW supplemental arginine (360 ARG; n = 5). Following estrous synchronization, ewes were individually fed rumen-protected arginine blended into 150 g ground corn, which was immediately followed with 650 g of a pelleted diet (2.40 Mcal ME/kg and 12.9 percent CP; DM basis) on d 8 to d 12 of the estrous cycle. Ewes fed 360 ARG generally had greater serum- arginine concentrations than CON, 90 ARG, and 180 ARG on d 11 (P ≤ 0.07) and d 12 (P ≤ 0.03). On d 11, arginine as a percent of total amino acid concentration was greater in 360 ARG compared with CON and 90 ARG (P ≤ 0.05). Total essential amino-acid concentration was elevated in 360 ARG compared with 90 ARG and 180 ARG (P ≤ 0.03) on d 12. Arginine supplementation increased peak systolic velocity in the corpus luteum (CL) for 360 ARG and 90 ARG compared to CON (P ≤ 0.04). Flow time (milliseconds) in the ovarian hilus was increased and CL was generally increased in 360 ARG compared to all other treatments (P ≤ 0.04 and P ≤ 0.09, respectively). Supplemental rumen-protected arginine had no effect on serum concentration of progesterone (P > 0.50). Results indicate that rumen-protected arginine supplemented to ewes at the rate of 360 mg/kg BW may increase circulating serum arginine concentration, in addition to increasing ovarian blood flow.
Key Words: Arginine, Ovarian Hemodynamics, Sheep
Sulfur Intake, Excretion, and Ruminal Hydrogen Sulfide Concentrations in Lambs Fed Increasing …
The objective of this research was to evaluate the effects of increasing dietary concentration of DDGS on S intake, excretion, and ruminal H2S gas concentrations in lambs. Sixteen wether lambs (36.7 kg ± 2.3 kg) were utilized in a completely randomized design. Treatments were based on increasing concentrations of DDGS in the final finishing diet and included: 1) 0 percent DDGS, 2) 20 percent DDGS, 3) 40 percent DDGS, and 4) 60 percent DDGS. Ruminal H2S concentrations were measured weekly via rumen puncture as lambs were adapted to their respective finishing diets. Feed, water, feces, and urine were collected over a 10 d collection period. Hydrogen sulfide gas concentrations did not differ (P ≥ 0.24) until d 7 when lambs fed increasing concentrations of DDGS had a linear increase (P = 0.009) in ruminal H2S concentrations. Linear increases (P < 0.001) in ruminal H2S concentrations were also observed on d 14, d 28, and d 35 in lambs fed increasing concentrations of DDGS. Dietary DDGS inclusion did not affect DMI (1.37 ± 0.07 kg·hd-1·d-1; P = 0.25). Sulfur intake from feed and water, as well as S excretion in feces and urine increased linearly (P ≤ 0.009) with increasing DDGS inclusion. Sulfur retention increased linearly (P = 0.02) with increasing inclusion of DDGS, although this does not reflect losses due to H2S. Increasing concentration of DDGS in the diet did not result in the occurrence of PEM. This research suggests that lambs excrete substantial amounts of S from DDGS and that water intake and urinary output increase with increasing S intake.
Key Words: Distillers Dried Grains with Solubles, Lambs, Polioencephalomalacia, Sulfur, Water Intake
Effects of Season of Kidding on Doe Performance in Commercial Boer Cross Does
Little information is available on the impact of season of kidding on doe performance in goats. However, many producers in the southeastern United States kid in the late fall and winter because of seasonal market trends. Weather conditions during this time tend to require higher labor and nutritional supplementation. Because of this, a study was designed to evaluate doe performance by comparing total birth, 60 d and 90 d kid weight, doe efficiency ratio, conception rate, and kid survival to weaning in two alternative kidding seasons. One hundred and twenty commercial, meat-type does were randomly assigned to either a fall (October – December) or spring (March – May) kidding season. Data collected included birth weight, birth type, sex, 60 d weight, and 90 d weight on the kids. Doe weight and body condition score were taken at weaning (90 d), and the efficiency ratio was calculated by dividing the total weight of kids at 90 d by the doe weight taken at weaning. Kidding season had an effect (P < .01) on doe weight at weaning, total weight at 90 d, and conception rate. Season of birth did not affect total birth weight (P = .21) or total 60 d weight (P = .38). Doe weight and total 90 d weight were higher for fall than spring kidding; however, conception rate was higher for spring kidding does. This research indicates that kidding season has an influence on total weaning weight per doe. However, differences in conception rate may decrease profitability of fall and early winter kidding herds.
Key Words: Meat Goat, Season of Birth, Doe Efficiency Ratio
Mixed Grazing Goats With Cattle on Reclaimed Coal Mined Lands in the Appalachian Region: Effects on Forage Standing Biomass,
Reclaimed coal-mined lands in Appalachia of the United States can be successfully utilized for beef cattle but the proliferation of invasive-plant species, such as autumn olive (Elaeagnus umbellata Thunb.) can limit this option. An experiment was conducted in 2006, 2007, and 2008 near Wise, Va. to determine the effects of cattle-alone grazing and mixed grazing of goats with cattle on forage standing biomass, forage botanical composition, and autumn olive. After the first sampling, forage standing biomass remained higher in cattle-alone grazing (P ≤ 0.002). Weed content was lower at the end of the grazing season in mixed grazing in all years (P < 0.03). Total autumn olive branch length was reduced by goat browsing in the mixed grazing treatment by the end of the experiment (P < 0.02). Total autumn olive shrub height was not affect by either treatment at the end of the study (P = 0.33). Goats grazing with cattle consumed plant species not preferred by cattle. Mixed grazing goats with cattle is a viable option for reclaimed coal-mined lands in Appalachia.
Keywords: Autumn Olive, Browse Species, Cattle, Goat, Grazing, Land Reclamation
Sheep & Goat Research Journal. Volume 25, 2010
A Review: The Use of Livestock Protection Dogs in Association with Large Carnivores in the Rocky Mountains
Livestock protection dogs (LPDs) in the United States have helped to protect livestock herds from certain predators, but expanding large-carnivore populations pose new challenges, and the number of LPDs killed by large predators is increasing. We conducted a literature review to identify LPD breeds that may be more suited for use around large carnivores, such as gray wolves. The use of spiked collars to increase the survivability for LPDs in areas of coexistence with large carnivore populations is also discussed. This paper advances the adoption of techniques and LPD breeds used outside of the United States in areas where large carnivores exist with livestock production.
Key Words: Bears, Carnivores, Livestock, LPD, Protection Dogs, Wolves
Effects of Human Chorionic Gonadotropin on Serum Progesterone Concentration During the First Weeks After Mating, Components of Pre-implantation Complete Blood Counts, and Number of Offspring…
Human chorionic gonadotropin (hCG) may boost progesterone production and attenuate maternal-immune response against concepti in ewes, increasing prenatal survival. The present study examined effects of repeated hCG administration after mating on serum progesterone concentration and complete blood counts (CBC) during early gestation, as well as offspring numbers at parturition. Fifty-six ewes were synchronized and mated, then administered saline (CON) or 100 IU hCG on d 4, d 7, d 10, and d 13 after estrus (d 0). Ewes not conceiving were mated again at subsequent estrus. Progesterone was measured on d 4 to d 15 and CBC on d 7 and d 11. In ewes pregnant at treatment, serum progesterone was greater (P < 0.050) in hCG-treated ewes than CON from d 7 through d 15 (final sampling day), while in ewes conceiving at subsequent estrus (after treatment), progesterone was greater (P < 0.050) in hCGtreated ewes on d 11 through 15 only. On d 7, total white blood cells (WBC) and lymphocytes (LYM) were greater (P < 0.050), mean corpuscular volume (P = 0.067) tended to be greater, and eosinophil fraction of WBC tended to be less (P = 0.068) in hCG-treated ewes. On d 11, red blood cells and hemoglobin were reduced (P < 0.050) and hematocrit tended to be reduced (P = 0.055) in hCG-treated ewes. Additionally, neutrophil fraction of WBC was greater (P < 0.050) in pregnant ewes on d 7, total LYM were less (P < 0.050) in pregnant ewes on d 11, and LYM fraction of WBC was less (P < 0.050) in pregnant ewes on d 7 and d 11 than in non-pregnant ewes, independent of treatment. No difference (P > 0.050) was found between treatments for number of ewes pregnant from mating at estrus just before treatment, the first estrus after treatment, the second estrus after treatment, or the number of ewes not pregnant. Frequency of single or multiple lambs at parturition did not differ (P > 0.05) due to treatment in ewes pregnant from mating at any estrus. Repeated administration of hCG during the first two weeks after estrus increased serum progesterone concentration in pregnant and non-pregnant ewes, influenced components of CBC, but did not appear to influence lambing rate or number of offspring at parturition when administered at these doses.
Key words: Ewes, Complete Blood Counts, Human Chorionic Gonadotropin, Progesterone
Feedlot Performance, Carcass Characteristics, and Muscle CLA Concentration of Lambs Fed Diets Supplemented with Safflower Seeds and Vitamin E
Sixty-eight Rambouillet ram lambs were used to evaluate the effects of safflower seed and vitamin-E supplementation on feedlot performance, carcass characteristics, and muscle-conjugated, linoleic-acid concentration. Lambs were fed finishing diets that were iso N and similar in estimated TDN containing safflower seed (SAFF) or no safflower seed (NOSAFF) in combination with 0 IU/d or 400 IU/d of supplemental vitamin E (NOVITE and VITE, respectively). Safflower seeds contained 43 percent oil with 79 percent linoleic acid, therefore SAFF diets were considered to contain 6 percent safflower oil. Final BW, DMI, ADG, and longissimus muscle area as measured by ultrasound did not differ (P > 0.10) between lambs fed SAFF and NOSAFF, or VITE and NOVITE. Gain:feed was lower (P = 0.06) for lambs fed SAFF compared to lambs fed NOSAFF (16.3 vs 14.3), but there was no difference (P = 0.45) in G:F between lambs fed VITE and NOVITE. Final weight, HCW, and fat thickness of slaughtered lambs were greater (P < 0.05) for lambs fed SAFF compared to NOSAFF (63.7 kg vs 59.7 kg final weight, 31.2 kg vs 29.0 kg HCW, and 0.3 cm vs 0.2 cm fat thickness); however, there were no differences (P > 0.16) in longissimus muscle area as measured by acetate traces, cooking loss, or Warner-Bratzler shear force between lambs fed SAFF versus NOSAFF. Final weight, HCW, fat thickness, longissimus muscle area, cooking loss, and Warner-Bratzler shear force did not differ (P > 0.19) between lambs fed VITE versus NOVITE. Dressing percentage was lower (P < 0.10) for lambs fed SAFF and VITE compared to lambs fed SAFF and NOVITE (47.6 percent vs 50.4 percent). Muscle from lambs fed SAFF had greater (P ≤ 0.001) concentrations of conjugated linoleic acid (CLA; 4.9 percent vs 0.6 percent), total polyunsaturated fatty acid (17.8 percent vs 7.2 percent), and total unsaturated fatty acids (57.7 percent vs 50.7 percent); and lower (P < 0.001) concentrations of total SFA (35.7 percent vs 40.7 percent) and total monounsaturated fatty acid (39.9 percent vs 43.5 percent) than muscle from lambs fed NOSAFF. Lambs fed VITE had greater (P = 0.02) concentrations of total saturated fatty acids in muscle than lambs fed NOVITE (39.7 percent vs 36.7 percent). Lipid oxidation of muscle did not differ (P > 0.32) between lambs fed SAFF and NOSAFF or VITE and NOVITE. Vitamin E had few effects on feedlot performance, carcass characteristics, or muscle-fatty-acid concentrations; however, safflower- seed supplementation increased muscle concentration of CLA, linoleic acid, and polyunsaturated fatty acid to saturatedfatty- acid ratio resulting in a meat product that may be more beneficial to human health.
Key words: Conjugated Linoleic Acid, Fatty Acids, Lamb, Lipid Oxidation, Meat
Pregnancy rates after ewes were treated with estradiol-17β and oxytocin
Ewes were assigned to the following treatments to determine whether estradiol-17β-oxytocin treatment affects luteal function and pregnancy rates on d 25: 1) diluent + saline (n = 26); 2) diluent + oxytocin (n = 25); 3) estradiol-17β + saline (n = 22); and 4) estradiol-17β + oxytocin (n = 24). On d 6 after expected estrus and mating, ewes received either i.v. injection of diluent or i.v. injection of 100 μg of estradiol-17β. Ten hours later, ewes received either i.v. injection of saline or i.v. injection of 400 USP units of oxytocin. Blood samples for progesterone assay were collected on d 6, d 7, d 8 (Period 1), d 16, d 18, d 20, d 22, and d 25 (Period 2). Transrectal ultrasonography on d 25 and progesterone concentrations were used to diagnose pregnancy. Neither estradiol-17β nor oxytocin affected pregnancy rates, and the estradiol-17β × oxytocin interaction was not significant. The pregnancy rate for diluent + saline was 61.5 percent; diluent + oxytocin, 76 percent; estradiol-17β + saline, 77.2 percent; and estradiol-17β + oxytocin, 62.5 percent. Progesterone concentration was greater (P < 0.05) in pregnant than in nonpregnant ewes (5.2 ± 0.3 ng/mL vs. 2.0 ± 0.6 ng/mL); the pregnancy status × period interaction was significant (P < 0.01); but estradiol-17β, oxytocin, and their interaction were not significant (P > 0.05). Treatment with estradiol-17β on d 6 after the expected onset of estrus and oxytocin 10 h later did not induce luteolysis or disrupt pregnancy in ewes.
Key Words: Sheep; Embryo Transfer; Estradiol; Oxytocin; Transcervical
Can Sheep and Cattle Rumen Microorganisms be Conditioned to Invasive Weeds?
The invasive plant species, Spotted knapweed (Centaurea maculosa Lam.) and common tansy (Tanacetum vulgare L.), are altering native rangeland communities in western North America (Tyser and Key, 1988; Jacobs, 2008). To increase our understanding of why sheep consume these species to a certain extent and cattle avoid them, in vitro dry matter digestibility (IVDMD), microbial gas production (MGP), and microbial purine concentrations (MPC) of C. maculosa or T. vulgare leaves or stems incubated in sheep or cattle rumen fluid were measured. Rumen microbes were not conditioned to these plants in Trials 1a and 1b, but were conditioned in Trials 2a and 2b. Total MGP of C. maculosa leaves or stems (Trial 1a; P < 0.004) and T. vulgare leaves (Trial 1b; P < 0.07) was less, but IVDMD of these plant parts were greater (P < 0.05) with cattle than sheep-rumen fluid. Conditioning ewe or cow rumen microbes to C. maculosa did not enhance 24-h MGP, IVDMD, or MPC of A. arundinaceus grass hay or C. maculosa leaves or stems (Trial 2a; P > 0.10). Conversely, conditioning ewe rumen microbes to T. vulgare increased (Trial 2b; P < 0.04) IVDMD of A. arundinaceus hay and T. vulgare leaves or stems. Centaurea maculosa leaves and stems and T. vulgare leaves were used by rumen microbes as a nutritious feedstuff and nutrient characteristics and overall low IVDMD and MPC suggest that T. vulgare stems represent a poor quality forage. To increase consumption, further research is warranted to determine species composition and physiological differences between sheep- and cattle-adapted rumen microbes.
Key Words: Centaurea Maculosa, Conditioning, Nutrient-Toxin Interactions, Rumen Microorganisms, Tanacetum Vulgare
Manipulating Sheep Browsing Levels on Coyote Willow (Salix exigua) with Supplements
Macronutrients and additives have been used to suppress or promote livestock intake of upland tannin-containing browse species, but to our knowledge this technique has not been applied to sheep that feed on tannin-rich species in riparian areas. The objective of this study was to determine the effect of four supplement regimes on coyote willow (Salix exigua) intake by sheep during the dormant and growing seasons. Twelve Western White Face lambs (48 kg ± 4.5 kg) were placed in individual pens and assigned to one of four treatments which consisted of a basal diet of sudangrass and supplements predicted to either suppress (whole corn or quebracho tannin) or promote (cottonseed meal or polyethylene glycol, PEG) willow intake. Each of the four supplements was tested with dormant and growing willow in a Latin rectangle design with three periods and six lambs per group. Basal diet (sudangrass) intake was not affected by either promoter nor suppressor treatments in either season. Cottonseed meal effectively promoted intake of willow compared to the control and PEG treatments (P< 0.05) in the dormant season. No difference was detected between the control, quebracho-tannin, and whole-corn treatments, although the latter tended to depress dormant-willow intake of lambs. None of the treatments altered intake of coyote willow in the growing-season trials. Protein and possibly corn-based supplements may be effective tools to manipulate sheep browsing levels of Salix exigua but need to be tested in a field setting before management strategies with supplementation can be applied.
Key Words: Targeted Grazing, Tannins, Cottonseed Meal, Whole Corn, Polyethylene Glycol, Quebracho Tannin
Effects of Physical Isolation on Serum and Salivary Cortisol and Components of Complete Blood Counts in Yearling Ewes
Isolation is often stressful to herd animals. The objective of this study was to compare changes in serum and salivary cortisol concentrations and complete blood count (CBC) components in physically isolated sheep. Twelve Suffolk x Hampshire yearling ewes (64 kg ± 1.2 kg) were held indoors in either a common pen or individual pens for 10 consecutive days. Individual pens did not allow physical contact, but did not obstruct vision or sound of adjacent sheep. Serum and whole blood samples (venipuncture) and salivary samples (oral swab) were collected at 0700 (AM) and 1300 (PM) on each day with the exception of day 1 (no AM sample). Additionally, intensive samples were taken in 15-min intervals over a 2-h period on days 1, 5, and 10 for correlation purposes. Serum and salivary cortisol concentrations (RIA) and specific blood components (CBC) were determined. Serum cortisol concentrations did not differ between treatments in AM (P = 0.452) or PM samples (P = 0.827). Similarly, salivary cortisol concentrations did not differ between treatments for either period (P > 0.768). Serum and salivary cortisol concentrations were closely correlated among all samples (r = 0.83, P < 0.001). White blood cells were reduced (P < 0.022) by isolation on days 1, 2, 4, 5, and 6 in PM samples, but AM samples were not affected (P = 0.594) by treatment. Isolation also reduced neutrophils (P < 0.037) and increased lymphocytes (P < 0.049) on days 1, 2, and 5 in PM samples only. Mean corpuscular volume was reduced (P < 0.001) by isolation on all days in both AM and PM samples. Conversely, mean corpuscular hemoglobin concentrations were increased (P < 0.009) in all samples. Hematocrit was reduced in isolated sheep from day 2 to day 6 in AM samples (P < 0.037) and on all but day 10 in PM samples (P < 0.050). Physical isolation did not appear to influence other CBC components, including red blood cells and hemoglobin concentration. In general, stress components were greater during the first two days of isolation, regardless of treatment. This was likely due to the unfamiliar environment. Data from this study indicate physical isolation of yearling ewes for 10 days without visual and auditory isolation did not elicit noticeable changes in cortisol concentrations, while alterations in immune components of CBC were generally mild and inconsistent. Although certain non-immune components were substantially affected by physical isolation, causes or physiological significance of these changes are unclear.
Key Words: Complete Blood Counts, Isolation Stress, Salivary Cortisol, Serum Cortisol
Research Note: Sheep Antiserum as an Antibody Supplement in Newborn Lambs
One of the greatest management challenges facing lamb producers today is keeping newborn lambs alive and healthy. More than 20 percent of lambs do not reach weaning, with 80 percent of those losses occurring in the first 3 days of life (Held, nonreference summary of professional observation). Starvation, hypothermia and scours account for most of those death losses. It has been estimated that 45 percent of all lambs that die during the first few days of life can be contributed to inadequate colostrum intake (McGuire et al., 1983). This can be contributed to ewe’s colostrum being poor quantity or quality; bad udders (mastitis, hardbag); dysfunctional teats; multiple births (triplets, quads); neglect from the ewe; orphaned or weak lambs; and diseases, such as ovine progressive pneumonia (OPPV) and Johnes.
The lack of or reduced colostrum intake leaves the newborn lamb without adequate antibody protection to certain infectious diseases causing the newborn lamb to become sick and possibly die (Sawyer et al., 1977). The most common infectious agents causing death in lambs are Clostridium perfringens (type C & D), Salmonella spp., Escherichia coli (E.coli), and Mannheima hemolytica ((Rook et al, 1990). Navel ill, septicemias, E.coli enteritis and peracute pneumonia are more common in 2- to 3-day old lambs that lack passive immunity. E.coli endotoxemia tends to show up at 7 to 10 days of age. A study at the U.S. Sheep Experiment Station showed that 46 percent of lamb mortality was caused by scours and 8 percent by pneumonia, both of which are likely related to the lack of immune protection in the newborn lambs (Gates et al., 2000).
An important management tool for protection to infectious diseases is to ensure that newborn lambs receive adequate antibody intake within the first hours of life (Vihan, 1988). Colostrum provides energy, protein, minerals, vitamins, water and, most importantly, antibody protection against the infectious diseases mentioned above. Lambs are born antibody deficient and have comprised immune systems until they ingest colostrums. Adequate antibody intake is important for all lambs to ensure good health, survivability, and performance (Rook et al, 1990).
The purpose of this research project is to determine if a sterile, irradiated, hyper-immune serum product derived from healthy, hyper-immunized sheep can be used as an antibody supplement in newborn lambs.
Substituting Corn Dried Distillers Grains for Cottonseed Meal in Lamb Finishing Diets: Carcass Characteristics, Meat Fatty Acid Profiles, and Sensory Panel Traits
The effects of replacing cottonseed meal (CSM) with corn dried distillers grains (DDG) on carcass characteristics, meat fatty acid profiles, and sensory panel traits were investigated in Rambouillet wether lambs. Lambs (n = 44) were individually fed ad libitum diets for 84 d containing DDG that replaced 0 percent (0DDG), 33 percent (33DDG), 66 percent (66DDG), or 100 percent (100DDG) of the CSM in a completely randomized design. Carcass characteristics, fatty acid profiles (weight percentage), and sensory panel traits from the LM were determined on 8 randomly selected wethers per diet. Carcass characteristics were not affected (P > 0.14) by diet. As DDG increased in the diet, extracted fat from the LM linearly increased (P = 0.004). The trans-9, 10, and 11 isomers of 18:1 and cis-vaccenic (18:1 cis-11) acid linearly increased (P < 0.09) in the LM, and linoleic (18:2 cis-9 cis-12) and arachidonic (20:4) acids linearly decreased (P < 0.02) as DDG increased in the diet. The CLA cis-9, trans-11 isomer quadratically increased (P = 0.07) in the LM as percentage of DDG increased in the diet. Increasing DDG in the diets quadratically affected (P < 0.05) cook-loss, initial and sustained juiciness, sustained tenderness, and flavor intensity. Meat from lambs fed 100DDG had less (P = 0.01) cook-loss and greater (P < 0.04) initial and sustained juiciness than meat from lambs fed 0DDG diet. Results indicated that partially or totally substituting DDG for CSM in lamb-finishing diets is acceptable and may enhance sensory traits.
Key Words: Carcass, Dried Distillers Grains, Feedlot, Lamb, Meat Fatty Acids, Sensory Panel Traits Introduction
Effect of Finishing Crossbred Meat Goats with a Similar Total Quantity of Finisher Ration Over Variable Duration
The objective of this research was to assess the effect of finishing weaned crossbred meat goats with a similar total quantity of finisher ration over variable duration on meat goat production performance measures. Thirty weaned crossbred kids were blocked by body weight and genotype and assigned to three different lengths of finishing periods (45 days, 90 days or 135 days). Each finishing period treatment was replicated in two 0.4 ha Joy chicory (Cichorium intybus L.) plots with 5 kids in each and supplemented with 138 kg of commercial finisher ration over 45 days, 90 days or 135 days. While total finisherration consumption (27.30 kg, 27.49 kg and 28.26 kg/head) and cost ($9.90, $9.83 and $9.76 for the 45-day, 90-day and 135-day-finishing durations, respectively) did not differ statistically, finisher ration cost-per-kg gain ($1.89, $1.54 and $1.39, respectively) decreased linearly (P < 0.05) and total live-weight gain (5.18 kg, 6.42 kg and 7.23 kg) and return-over-finisher ration ($4.42, $7.79 and $19.82, respectively) increased linearly (P < 0.05) with increase in lengthof- finishing period. Finishing weaned meat goats over a longer duration with the same quantity of finisher ration was economically beneficial if labor costs are not included. When labor cost was factored into the equation, cost per kg gain increased and return-over-feed cost and labor decreased linearly (P < 0.05) with increase in length-of-finishing period from 45 days to 135 days of finishing. Finishing over a longer period resulted in negative return, which decreased linearly from -$0.08 for the 45 days, to – $1.21 for the 90 days and -$3.36 for the 135-day finished groups. It was not economically beneficial to finish crossbred meat goats using paid labor. Bonelessretail cut from the leg, loin, shoulder and rack increased linearly (P < 0.05) from 45 days to 135 days of finishing. No significant difference was observed in backfat thickness while kidney, pelvic and heart fat tended to be higher for the 45- day-finished group.
Key Words: Meat Goat, Finishing Period, Chevon Production, Return Over Finisher Ration Cost
Evaluation of Ultrasonography to Measure Fetal Size and Heart Rate as Predictors of Fetal Age in Hair Sheep
There is little information available on methods to estimate fetal age of hair sheep. The objective of this study was to determine whether crown-rump length (CRL) and/or fetal heart rate (FHR)could be used to predict fetal age in hair sheep using transrectal B-mode and Doppler ultrasonography. St Croix White, Barbados Blackbelly and Dorper X St. Croix White ewes (n = 54) were scanned weekly beginning 28 d after a successful mating. Linear array B-mode ultrasonography (5 MHz) was used to measure CRL and visual FHR, and Doppler ultrasonography was used to measure audible FHR. Due to the size of the fetus CRL was not measurable after 42 d of gestation, and visual FHR was not measurable after 70 d. Audible FHR was not consistently measurable before 35 d but could be measured through 140 d of gestation. Single fetuses had greater CRL (P < 0.01) than multiple fetuses at d 35 and d 42 of gestation. There was no difference (P > 0.10) in visual or audible FHR between single and multiple fetuses. Visual FHR was higher (P < 0.0001) than audible FHR at 49 d of gestation. Both CRL and audible FHR had a linear relationship with days of gestation for single and multiple fetuses. The relationship between days of gestation and visual FHR was best described by a cubic equation for single fetuses and a quadratic equation for multiple fetuses. Accuracy of the regression equations and the software in the ultrasound machine was evaluated by scanning a set of ewes (n = 51) also with known breeding dates. Both the equations and the software underestimated actual age of single fetuses by 2.5 d (P < 0.01). For multiple fetuses the equation overestimated the age by 1 day, and the software underestimated age by over 2 d (P < 0.01). Overall, the regression equations underestimated fetal age by 1 d and the software underestimated fetal age by more than 2 d (P < 0.004). Fetal age can be estimated with acceptable accuracy in hair sheep breeds, regardless of fetal number, using existing methods that were developed using other breeds of sheep.
Key Words: Sheep; Fetus; Ultrasonography; Fetal Heart Rate
Protein Supplementation of Low-quality Forage: Influence of Frequency of Supplementation on Ewe Performance and Lamb Nutrient Utilization
Supplementation frequency (SF) of CP for ruminants consuming low-quality forage can be decreased to once every 7 d; however, no data are available describing the effects of decreasing SF to once every 10 d. Our objectives were to evaluate the influence of length of SF on forage intake, digestibility, N balance, digested N retained, and plasma concentration of urea-N in lambs and reproductive performance in pregnant ewes. Supplementation frequency included daily (D), once every 5 d (5D), or once every 10 d (10D) supplementation, and an unsupplemented control (CON). Sixteen wethers (31 ± 1 kg BW) were individually fed in a digestibility study (n = 4 wethers / treatment). The amount of CP supplied by each supplement was approximately 0.15 percent of BW/d (averaged over a 10-d period) and formulated to meet CP requirements. Sixty pregnant Rambouillet ewes (75 ± 0.4 kg BW) in the last third of gestation were used in a performance study. The amount of CP supplied by each supplement was approximately 0.11 percent of BW/d (averaged over a 10-d period) and formulated to meet CP requirements, not including CON. Basal diets consisted of low-quality (5 percent CP) barley straw. Total DMI and OM intake were not affected (P ≥ 0.93) by supplementation. However, forage DMI, OM intake, and N intake by lambs decreased (P ≤ 0.06) linearly as SF decreased. Apparent total tract digestibility of N for supplemented lambs was approximately 300 percent greater (P < 0.001) than the CON, with no difference (P = 0.57) as SF decreased. Digested N retained and N balance were greater (P ≤ 0.01) for supplemented wethers than for CON, with no difference (P > 0.31) due to SF. Plasma urea (PU; mM) was measured over the10-d period. Supplemented lambs had increased (P < 0.001) PU compared with CON, but was not effected (P = 0.32) by SF. Crude protein SF had no affect (P > 0.21) on postlambing weight change, pre- and postlambing BCS change, lambing date, and average lamb birth weight. Results suggest ruminants consuming low-quality forage can be supplemented with protein as infrequently as once every 10 d, while not negatively affecting nutrient digestibility or ewe performance.
Key Words: Crude Protein, Lamb, Reproduction, Sheep, Supplementation Frequency
Effects of Supplemental Cobalt on Nutrient Digestion and Nitrogen Balance in Lambs Fed Forage-based Diets
The objective of this study was to determine the effects of supplemental cobalt on nutrient digestion and nitrogen balance in lambs fed a forage-based diet. Sixteen wether lambs (initial BW = 28.6 ± 1.3 kg) were used in a two-period crossover design and randomly allotted to one of two treatments being ad libitum grass hay (7.1 percent CP, 68.5 percent NDF, DM basis) plus 45.0 g of dried distillers grains with a commercial mineral formulated to provide 1.1 mg/d of cobalt (CONTROL) in the form of cobalt carbonate or a commercial mineral containing supranutritional levels of cobalt carbonate providing 7.1 mg/d of Cobalt (COBALT). Experimental periods were 21 d in length and consisted of 15 d for diet adaptation and 6 d of total fecal and urine collection. Forage DM, OM, and NDF intake tended to increase (P = 0.091) when lambs consumed COBALT. Despite increased forage intake; fecal DM, OM, and NDF flow (P ≥ 0.654) did not differ between cobalt levels. Total tract DM, OM, and NDF digestibility ( percent of total intake) did not differ (P ≥ 0.591) between CONTROL and COBALT. No differences were observed between cobalt levels for total N intake (P = 0.129), total tract N digested (g/d; P = 0.135), or urine N output (P = 0.812). The provision of additional cobalt to lambs did not increase (P = 0.251) N retention. Providing lambs a forage-based diet containing 7.1 mg/d of cobalt tended to increase forage intake but did not affect total tract digestibility or N balance.
Key Words: Cobalt; Digestion; Lamb; Nitrogen Balance
Effect of Feeding System on Meat Goat Growth Performance and Carcass Traits
This research sought to evaluate the effect of diet on meat-goat-growth performance, carcass traits, and fatty acid profiles of the meat product. Fifty-six meat-goat kids were allocated to one of two feeding systems. The control treatment (FORAGE; n = 27) was a forageonly system that was composed of grazing and chopped hay. The treatment group (GRAIN; n = 28) was fed one percent of their BW grain mix in addition to the FORAGE diet. Animals were fed to a target end weight of 36.4 kg. Animals on the GRAIN treatment had higher ADG and fewer days on feed (P < 0.05). Dietary treatment did not impact (P > 0.10) dressing percent, tenderness, or fat-cover score. Animals on GRAIN had more desirable carcass-selection scores (P < 0.01). The percentage of saturated fatty acids, unsaturated fatty acids, MUFA, PUFA, omega-6, and omega-3 fatty acids in longissmus muscle (P > 0.10) was not impacted by diet. Animals on GRAIN tended to have a higher omega-6: omega-3 ratio (P = 0.06). Feeding low levels of concentrates to meat goats increased ADG and reduced days on feed without impacting dressing percentage, fat- cover score, tenderness and fatty acid composition of the meat product. When evaluating the production costs of both systems, the benefits of increased rate of gain and fewer days on feed may not offset the added cost of production.
Key Words: Meat Goat, Growth Performance, Carcass Traits, Fatty Acids
Sheep & Goat Research Journal. Volume 24, 2009
Wool Price Differences by Preparation in the United States
Price differences for U.S. wools by preparation and type were examined using data collected from warehouses and pool sales across the United States over the period 1993 to 2002. The goal was to determine premium/discounts in wool prices by preparation and type, controlling for season, year, region, average-fiber diameter, and lot size. Unlike previous research efforts, a hedonic model was used in this investigation.
The hedonic price model explained about 83 percent of the variation in U.S. wool prices. Seasonality in U.S. clean wool prices was evident. Wool prices received by producers from January to March as well as from October to December were significantly lower from 5.9 percent to 17.4 percent than those prices in September. Wool prices in June were roughly 8 percent higher than those of September. In accord with prior expectations, U.S. clean wool prices were highest in 1995 and 1997. Prices in remaining years from 1993 to 2002 were significantly lower from 11.8 percent to 52.2 percent relative to the base year of 1997. Further, U.S. clean wool prices were discounted by 7.9 percent and 9.8 percent respectively, in the Eastern and Western regions of the United States relative to the Central region.
In line with prior research, prices of table-skirted and classed wool were significantly higher than original bag wool by slightly more than 8 percent. Significant differences among wool types also were evident. In particular, U.S. clean prices of TSC and BOU Main Line Wool were higher by 23.5 percent over the OB wool breed. Significant differences were noted as well among wool types from OB. Among wool types, the premiums/discounts relative to OB wool breed type were quite large in magnitude.
U.S. clean wool prices were sensitive to change in average diameter. The elasticity of clean price with respect to average fiber diameter was estimated to be roughly -1.42. Lot size, as measured by grease weight, also positively affected U.S. clean prices. The elasticity of clean price with respect to lot size was estimated as 0.16.
Key Words : U.S. Wool Prices, Hedonic Price Model
Evaluating Nutritional Status of Dorper and Rembouillet Ewes in Range Sheep Production
Mature Dorper and Rambouillet ewes were maintained together for 2 years in a range environment to evaluate their nutritional status before and during gestation. During Years 1 and 2, nutritional status of mature Dorper (n = 46 and 71, respectively) and Rambouillet (n = 33 and 81, respectively) ewes were evaluated during pre- (August), mid- (late October) and late gestation (December). Ewes were selected from multiple Dorper (n = 20) and Rambouillet (n = 13) flocks. All ewes performed well while grazing and did not lose weight or BCS during gestation, except in Year 1 during late gestation when Dorper and Rambouillet ewes both lost weight. Compared to Rambouillet ewes, Dorper ewes had higher BCS (P < 0.03) during pre-gestation in Year 1 and throughout Year 2 (P < 0.01), but similar BW (P > 0.10) during both years. Dorper ewes tended to have greater IGF-1 concentrations (P < 0.08) during Year 1 in pre-gestation, and maintained greater IGF-1 concentrations (P < 0.005) than Rambouillet ewes throughout Year 2. Dorper ewes had less serum NEFA and serum urea nitrogen (P < 0.05) than Rambouillet ewes during mid- and late gestation in Year 2. Results suggest that nutritional status differed at times, between Dorper and Rambouillet ewes in a range production system during gestation. Reasons for Dorper ewes having higher BCS and serum IGF-1 concentrations throughout gestation need to be investigated further.
Key Words : Dorper, Rambouillet, Insulin-like Growth Factor-1, Metabolites, Rangelands, Sheep
Effect of Expected Peripheral Concentrations of Progesterone on Ovulation Rate and Litter Size in Barbados Blackbelly Ewes
To determine whether luteal phase concentrations of progesterone (P4) altered ovulation rate and litter size in ewes, mature Barbados Blackbelly ewes were assigned to groups treated so that they would be expected to have low, medium or high P4 (n = 23 or 33 per group in two seasons). Each ewe on low and high P4 received a P4-containing intravaginal insert from d 4 through d 14 after estrus. Ewes in low group were given PGF2á on d 6 to regress corpora lutea (CL). Ewes with medium P4 were untreated. Ovaries in 10 or 8 ewes per group (in seasons 1 and 2, respectively) were observed by transrectal ultrasonography from d 6 of the pre-breeding cycle until ovulation, and in all ewes on d 7 after breeding (one ram to 10 to 16 ewes). Numbers of follicles that disappeared at estrus (P < 0.02) and of CL formed (P < 0.001) increased linearly with decreasing P4. As P4 decreased, more follicles disappeared from the penultimate than the final wave of development. Disappearance of follicles was correlated with CL formed (0.53; P < 0.0001). Conception rates did not differ with expected concentration of P4. Lambs born per CL decreased linearly (P < 0.001) with decreasing concentrations of P4. Prolificacy did not differ (P > 0.32) among ewes treated to have low, medium or high concentrations of P4 (2.0, 1.9, and 1.9 ± 0.1 lambs, respectively), despite greater ovulation rates. On a practical basis, altering progesterone before breeding did not change productivity of the ewe in terms of number of lambs born.
Key Words : Barbados Blackbelly, Ovulation Rate, Progesterone, Prolificacy, Ewe, Sheep
Post-weaning Management of Lambs Alters Subsequent Feedlot Performance and Tissue Deposition
Backgrounding lambs on forage-based diets after weaning may provide producers with alternatives to traditional marketing of lambs directly to feedlots. Our objective was to evaluate feedlot performance of lambs from different backgrounding treatments. Seventy-two crossbred lambs were randomly assigned to one of four backgrounding treatments. Treatments were imposed after traditional, range-weaning practice (140 d of age). Treatments were: 1) drylot ad libitum access to 80:20 alfalfa:barley pellets (PELLET); 2) cool-season, grass-paddock grazing (GRASS); 3) unweaned, dormant-range grazing (LATE WEAN); and 4) weaned, dormant-range grazing (RANGE). After 29 d of backgrounding, lambs within backgrounding treatment were assigned to feedlot pens (3 pens/treatment). Lamb-BW and ultrasound measurements were taken at weaning (d-29), after backgrounding (d 0), after transition to 70 percent grain diet (d 19), and at the end of the feedlot period (d 68). Lambs backgrounded on PELLET had greater BW (P < 0.10) at d 0 and d 68 than lambs assigned to other treatments. Feedlot DMI of PELLET lambs was greater than all other treatments, and feedlot ADG of PELLET lambs was greater than LATE WEAN and RANGE lambs (P < 0.10). At the end of the feedlot period (d 68), ultrasound measures of LM were greater (P < 0.05) for GRASS than either LATE WEAN or RANGE when BW on d 68 was included as a covariable. No differences (P > 0.10) in 12th-rib-fat thickness were detected among treatments at d 68. Results from our 2007 study indicate that 29-d-background treatments on dormant range diminished subsequent-feedlot performance; however, GRASS backgrounding had similar feedlot performance to PELLET backgrounding.
Key Words: Backgrounding, Feedlot Performance, Tissue Deposition Lamb
Substituting distillers dried grains for cottonseed meal in lamb-finishing diets: growth, wool characteristics, and serum NEFA, urea N, and IGF-1 concentrations
Effects of replacing cottonseed meal (CSM) with corn distillers dried grains (DDG) on growth, wool, and serum NEFA, urea N (SUN), and IGF-1 concentrations were investigated in Rambouillet wether lambs. Lambs (n = 44) were individually fed ad libitum diets for 84 d containing DDG that replaced 0 percent (0DDG), 33 percent (33DDG), 66 percent (66DDG), or 100 percent (100DDG) of the CSM in a completely randomized design. Diet × day interactions were not observed (P > 0.12) for BW, ADG, DMI, degradable protein intake, or G:F. As DDG increased in the diet, ADG and G:F decreased quadratically (P = 0.08), but no difference (P = 0.13) in daily DMI was observed. Lambs fed 100DDG diet had similar (P > 0.23) ADG, average DMI, and G:F compared to lambs fed 0DDG diet. A diet × day interaction (P < 0.001) was observed for SUN, but not for serum NEFA or IGF-1 concentrations (P > 0.16). At times, SUN increased (P < 0.10) as DDG increasingly replaced CSM, which was attributed to an increase (quadratic, P < 0.001) in degradable protein intake. Serum NEFA decreased linearly (P < 0.08) and serum IGF-1 decreased quadratically (P < 0.05) as DDG increasingly replaced CSM in the diets. Wool characteristics were not affected (P > 0.10) by diet. Results indicated that DDG can replace all the CSM in lambfinishing diets without negatively affecting growth, efficiency of gain, or wool characteristics, and can potentially reduce cost of feed•kg-1 gain.
Key Words: Cottonseed Meal, Distillers Dried Grains, IGF-1, Lambs, Wool
Sheep & Goat Research Journal. Volume 23, 2008
Nutrient Utilization in Polypay and Percentage White Dorper Lambs Fed a High-Roughage and a High-Concentrate Diet
Nutrient utilization was compared in Polypay (PP), ? White Dorper 1/2 Polypay (1/2 D), and 3/4 White Dorper ? Polypay (3/4 D) lambs. Six lambs (35 kg; 5 months) of each genetic type were fed a high-roughage diet (HR) of 60-percent ground-grass hay and 40-percent concentrate in Phase 1 (14-day diet and digestion crate adjustment and 7-day fecal and urine collection). Lambs were offered a daily ration (2-percent BW) in equal amounts two times daily. Fecal aliquots (10 percent) were collected daily, dried, and composited by lamb. Composites were analyzed for dry matter (DM), nitrogen (N), neutral-detergent fiber (NDF), and acid-detergent fiber (ADF). Aliquots (1 percent) of daily-urine outputs were composited by lamb and analyzed for N. Digestibilities of DM, N, NDF, and ADF were similar across genetic types. Nitrogen-retention values (percent of N intake) were 9, 13, and 11 for PP, 1/2 D, and 3/4 D lambs, respectively. Percent of digested N retained was 12, 19, and 16 for PP, 1/2 D, and 3/4 D, respectively. Upon completion of Phase 1, lambs were adjusted to a 90-percent concentrate and 10-percent ground-grass hay diet (HC) in Phase 2. Aliquots of feces and urine were collected and analyzed as described for Phase 1. Digestibility of HC diet DM was higher in 1/2 D (P = 0.03) and 3/4 D (P = 0.09) lambs than in PP. Digestibility of N, NDF, and ADF was not affected by genetic type. Although N retention values were numerically highest in 1/2 D lambs, differences were not statistically significant. Overall utilization of the high-quality diets fed in this study tended to be highest in the 1/2 D lambs.
PRNP Genotype and Sale Price – Associations of prion protein genotype with sale price in a flock of purebred Polled Dorsets
The objectives of this study were to determine prion protein (PRNP) genotype frequencies in a flock of Polled Dorsets and to estimate the association of PRNP genotype with the value placed on PRNP genotype by buyers of elite breeding stock. The association between selling price and genotype was determined for 161 sheep. Sale price and 90-d BW were analyzed with a mixed model that included PRNP genotype, year-season of birth, and litter size (90-d BW only) as fixed effects; animal, litter, and error as random effects; and 90-d BW as a covariate (sale price only). The frequencies of R/R (homozygous scrapie resistant), Q/R, and Q/Q (homozygous scrapie susceptible) genotypes were 25 percent, 49 percent, and 26 percent, respectively. The effect of genotype on sale price was highly significant, and buyers of elite breeding stock paid $799 more for R/R individuals than Q/Q individuals. The allele substitution effect for the R allele was $397. Sale prices for Q/Q sheep were significantly associated with 90-d BW and increased approximately $34 for a one kg increase in BW. The effect was not as strong ($22 per kg) and not significant for R/R sheep. Buyers of elite breeding stock are placing a strong emphasis on PRNP genotype relative to performance characteristics, indicating that sheep breeders are engaged in national scrapie-eradication efforts.
Key Words: Dorset, Genotype, Prion Protein, Scrapie
The Yellowing Propensity of Rambouillet Wool
The yellowing propensity of Rambouillet wool was evaluated. One hundred greasy side samples of Rambouillet ewes were collected in the spring of 2007, and 142 greasy side samples were collected from Rambouillet rams during the October 2006 Ram test. The propensity to develop yellow discoloration was determined on each of the greasy wool samples. After scouring, average-fiber diameters were obtained. Absorbance measurements of supernatant liquids clearly indicated there was a wide range in yellowing propensity for both the rams and the ewes. This would imply that is would be possible to include yellowing propensity in a selection program, allowing producers to discriminate against those animals with a propensity to develop yellow discoloration. There was no significant difference between the yellowing propensity of the ram or ewe wool and fiber diameter.
Key Words: Wool, Yellowing Propensity, Rambouillet
Feeding of DDGS in Lamb Rations
Summary Little scientific documentation is available that evaluates maximum levels of dried distiller grain with solubles (DDGS) in lamb-finishing rations. The objective of this research was to evaluate the effect of feeding increasing levels of DDGS in lamb-finishing rations on lamb performance and carcass characteristics. Two-hundred forty Western, white-faced Rambouillet wether and ewe lambs (31.7 ?? 0.6 kg BW) were stratified by weight and sex, randomly allotted to one of 16 pens, and assigned to treatment (n = 4). Diets were balanced to meet CP, energy, and Cu requirements; however, treatments were not formulated to be isocaloric or isonitrogenous. The basal diet consisted of alfalfa hay, soybean meal, barley, and a trace mineral supplement. Dried distillers grains with solubles replaced barley and soybean meal at 0 percent, 20 percent, 40 percent, and 60 percent of the diet, respectively (DM basis). Sulfur concentrations of diets were 0.22 percent, 0.32 percent, 0.47 percent, and 0.55 percent for the 0 percent , 20 percent , 40 percent , and 60 percent diets, respectively. Thiamin was included at 142 mg??hd-1??d-1 (DM basis) in all rations for the prevention of polioencephalomalacia. Rations were mixed, ground, and provided ad-libitum. Lambs were weighed on day 0, 32, 56, 83, and 111. Lambs were harvested after the 111 d feeding trial and carcass data collected. Performance and carcass data were analyzed as a completely randomized design. The model included the fixed effect of DDGS treatment and the random effect of pen nested in treatment. Contrast statements included 1) 0 percent vs DDGS inclusion; 2) linear effect of DDGS inclusion; and 3) quadratic effect of DDGS inclusion. Final weight, ADG, G:F, mortality, hot- carcass weight, leg score, carcass conformation score, fat depth, body wall thickness, ribeye area, quality and yield grade, and boneless closely trimmed retail cuts were not affected by treatment (P ??0.15). Feed intake increased in a linear manner (P < 0.001) as level of DDGS inclusion increased. Additionally, flank streaking increased quadratically (P = 0.09) as level of DDGS inclusion increased. Dried distillers grains with solubles maintained lamb performance and had no negative effect on lamb carcass traits. Maximizing the use of DDGS may become economically feasible for lamb feeders when prices become favorable compared to conventional dietary ingredients; however, the level of use of supplemental thiamin for the prevention of potential S-induced polioencephalomalacia in lambs needs to be further evaluated.
Key Words: Dried Distillers Grains with Solubles, Lamb, Sulfur, Thiamin
Sheep & Goat Research Journal. Volume 22, 2007
Weaning Weights in a Range Purebred Merino and Crossbred Merino x Rambouillet Flock
The Rafter 7 Merino flock was initiated in Nevada in 1990 with the purchase of 500 purebred Rambouillet ewes. A gradeup program was initiated using Australian Merino genetics with the aim of developing a purebred Merino flock. Early in the project the Rafter 7 Merino line was created, which is approximately 5/8 Merino and 3/8 Rambouillet and has been a closed line since 1999. In a genetic selection program that includes weaning weight, weights must be adjusted for environmental factors. The present study investigated factors influencing weaning weight in 9,594 lambs.
Results show a decrease in lamb weaning weights with the inclusion of Merino blood in the lines. At weaning, rams were heavier than ewes (P < 0.001) and weights decreased with increased litter size (P < 0.001). Lambs born from 2-year-old dams had lower weaning weights than lambs born from older dams (P < 0.01), and lambs born from 5-year-old dams had lower weaning weights than lambs born from 3-year-old dams (P < 0.05). Weaning weight of lambs born from 3-, 4-, 6-, and 7-year-old dams did not significantly differ.
Multiplicative-adjustment factors for adjusting lamb weaning weights to a common sex, age of dam, and birth-rearing type were compared with values from the Report of the National Sheep Improvement Program Technical Committee. Adjustment factors were slightly lower for triplet ewes and rams born from a 3- to 6-year-old dam. Other adjustment factors were very similar, suggesting that adjustment factors derived from more intensive production systems are applicable to our extensive production systems as well.
Peanut Stover and Bermudagrass Hay for Wethers on Summer Hardwood Rangeland in North Central Texas
Goats in the south-central United States raised on rangeland often face a mid-summer forage quantity and nutritivevalue deficit that may be mitigated by feeding inexpensive hay or stover. Four wethers (Boer X Spanish goats) were assigned to wooded rangeland paddocks (eight head ha-1, two replications) and supplemented with either peanut (Arachis hypogea) stover (10 percent crude protein (CP)) or coastal bermudagrass (Cynodon dactylon) hay (12 percent CP) at 0.5 percent or 2.0 percent BW with two unsupplemented paddocks as control treatments. The hay and stover were also fed to wethers ad libitum in a traditional feedlot and compared to a complete feed ration (four head pen-1, two replications). For 10 weeks from July to September in 2002 (216 mm rainfall) and in 2003 (354 mm rainfall) average daily gains (ADG) were measured, while herbage availability, and ADF, ADL, NDF, and CP concentrations of the primary browse species were determined. Goats receiving 0.5 percent BW bermudagrass in 2002 had greater ADG than those in the control and 0.5 percent BW peanut paddocks (P < 0.1). There were no differences in ADG among goats fed 2.0 percent BW of bermudagrass and peanut stover or control animals in 2002. No differences in ADG were measured in 2003 when browse nutritive value was the same but quantity was 26 percent lower than 2002. Goats on the complete ration in the drylot had greater (P < 0.1) ADG than goats fed either hay or stover ad libitum both years. Goats on complete feed in the drylot had greater (P < 0.05) dressing percentages than animals fed either stover or hay (45 percent, 37 percent and 31 percent, respectively). Supplementing goats on hardwood range with bermudagrass hay at 0.5 percent BW improved ADG only when there were sufficient quantities of high-quality browse.
Growth and Carcass Characteristics in Goat Kids Fed Grass- and Alfalfa-Hay-Based Diets with Limited Concentrate Supplementation
Two experiments were conducted to evaluate the effect of feeding legume hay (alfalfa; Medicago sativa L.) or mixed-grass hay on ADG and carcass characteristics of growing goats. In Experiment 1, 24 Spanish kids, equally representing female, intact male and wether goats, were pen-fed ad libitum either chopped alfalfa (16.8 percent CP) or mixed grass hay (9.4 percent CP) (3 pens/diet) and a corn/soybean meal supplement (16 percent CP) at 1.5 percent BW for 102 d. Goats were harvested at a commercial abattoir. Average daily gain (62 vs. 37 g/d; P < 0.01), carcass weight (14.8 vs. 12.8 kg; P < 0.05) and dressing percent (52.9 percent vs. 50.4 percent; P < 0.05) were higher in alfalfa than grass-hay-fed goats, respectively. Backfat and percentage kidney/pelvic fat was lower (P < 0.05) in bucks (0.12 cm and 1.8 percent) than in does (0.17 cm and 5.7 percent) and wethers (0.22 cm and 4.0 percent). In Experiment 10-month-old Boer and Boer-cross wethers (n=16) were penfed ad libitum either chopped alfalfa (15.2 percent CP) or grass hay (10.9 percent CP) for 84 days. Forage was supplemented with concentrate (16.3 percent CP) at 1 percent of BW. Carcass characteristics were determined as described for Experiment 1. Wethers fed alfalfa hay had a higher ADG (158 vs. 119 g/d; P < 0.01) and dressing percentage (54.0 percent vs. 52.2 percent, P < 0.05), but did not differ in other carcass characteristics. Alfalfa feeding improved growth rate and dressing percentage, but had no effect on other carcass characteristics, whereas sex class influenced primarily carcass-fat content.
Western Snowberry Response to Fire and Goat Browsing
Managers of pastures in the northern tallgrass prairie region are faced with incomplete control of aggressive woody plant species, such as western snowberry (Symphoricarpus occidentalis Hook.) due to its high sprouting ability after fire or mowing and the reluctance of managers to use herbicides, which may harm desirable plant species. The objective of this study was to compare western snowberry response to fire and browsing by goats. The study was conducted from 2002 through 2006 at South Dakota State University?s Oak Lake Field Station in eastern South Dakota. Small, fenced plots of nativeprairie vegetation infested with western snowberry were established on burned (fall 2001) and unburned (>30 years) sites and grazed by goats for three to five days in late June. Western snowberry foliar cover, plant height, stem density and seed production were measured each year. Annual goat browsing in late June reduced western snowberry plant height and seed production in burned and unburned sites, but did not change foliar cover. Fire also reduced plant height and seed production. Stem density remained unchanged after four years of annual goat browsing or five years post fire and was unchanged in controls. Reducing nuisance, resprouting, woody species, such as western snowberry, in grasslands is difficult, but annual goat browsing and/or combination with frequent fire (
Superovulation in Sheep: Number and Weight of the Corpora Lutea and Serum Progesterone
To determine similarities and differences between nonsuperovulated and superovulated ewe models, data collected from several experiments (1989 through 2005) were analyzed. Mature non-pregnant non-superovulated (n = 91) or superovulated (n = 299) Western range-type ewes were used for evaluation of luteal function. To induce superovulation, ewes were injected twice daily with FSH on days 13 to 15 of the estrous cycle. At corpora lutea (CL) collection on day 5 or 10 of the estrous cycle, the number of CL was determined. For selected ewes, the CL were weighed and blood samples were collected for determination of progesterone (P4) concentration in serum. Each year, a similar (P > 0.1) number of ovulations/ewe was induced by FSH treatment (range from 12.4 ? 2.0 to 20 ? 2.5/year). Superovulated ewes had greater (P < 0.001) number of CL than non-superovulated ewes (16.2 ? 0.5 vs. 1.9 ? 0.1). Weight of CL on day 5 of the estrous cycle was similar for superovulated and non-superovulated ewes (252.2 ? 4.1 vs. 224.7 ? 15.6 mg/CL), but on day 10, weight of CL from superovulated ewes was less (P < 0.05) than from non-superovulated ewes (379.9 ? 4.0 vs. 598.7 ? 18.5 mg/CL). Luteal tissue mass per ewe was greater (P < 0.001) for superovulated than non-superovulated ewes on days 5 (3.7 ? 0.4 vs. 0.5 ? 0.1 g) and 10 (6.1 ? 0.5 vs. 1.2 ? 0.1 g) of the estrous cycle. Serum P4 concentration on day 5 of the estrous cycle did not differ statistically (P > 0.1) for superovulated vs. non-superovulated ewes (2.3 ? 1.1 vs. 1.3 ? 0.1 ng/ml), but on day 10 tended to be greater (P < 0.06) in superovulated than non-superovulated ewes (5.8 ? 1.3 vs. 3.8 ? 0.3 ng/ml). When P4 concentration in serum was expressed per g of luteal tissue mass, values were similar for non-superovulated and superovulated ewes on days 5 and 10 of the estrous cycle. Moreover, all P4 values were greater (P < 0.05) on day 10 than on day 5 of the estrous cycle. Thus, despite some differences in CL number and CL weight, the major function of the CL, P4 production does not seem to be altered in superovulated ewes compared with non-superovulated ewes. Therefore, these data indicate that our superovulated ewe model may be used for studies of luteal function.
Cash Versus Contract Marketing in the U.S. Lamb Industry
Lamb operations in the United States are experiencing unfavorable market conditions, such as declining breeding inventories, stagnant domestic lamb consumption, and increasing competition from imported lamb. To more effectively compete, some operations may turn to nontraditional marketing arrangements, such as use of contracts, to purchase and sell lambs. To determine the extent of alternative marketing arrangements (AMAs) use in the U.S. lamb industry, we conducted a nationally representative mail survey of lamb producers and feeders. We received 302 completed surveys (53 percent weighted response rate). The survey collected information on purchases, sales and pricing methods, reasons why operations use their choice of marketing arrangements, and operation characteristics. We compared small and large operations, as well as Eastern and Western U.S. operations. Primarily U.S. lamb operations use cash-marketing methods to purchase and sell lambs. However, there appears to be a slight trend away from auction markets toward other types of cash-market transactions, such as direct trade. Large operations are more likely to use AMAs than small operations. Likewise, Western U.S. operations are more likely than Eastern operations to use AMAs. Large operations use AMAs to reduce risk, while small operations use AMAs to sell their lambs at higher prices.
Winter Grazing Systems for Gestating Ewes
Four winter-feeding systems for gestating ewes were investigated over a 3-year period. The systems investigated were: 1) low-density corn; 2) high-density corn; 3) fescue regrowth; and 4) round-baled hay. Effects on ewe performance and winter-feed costs were determined. An average of 118 mature (3 to 7 year old) Hampshire x Dorset ewes (avg initial BW = 91.6 kg) were used each year. Each of the wintering-grazing treatments was replicated by two fields, and the hay treatment was replicated by two drylot pens. The low- and high-density corn treatments were planted to achieve densities of approximately 54,000 and 91,000 corn plants/ha, respectively. Each replicate corn field was 0.4 ha and contained 12 ewes. The stockpiled fescue treatment consisted of replicate fields of 0.8 ha, each containing 12 ewes. For the hay treatment, first-cutting fescue hay was offered free choice in replicate drylot pens of 23 ewes each. Ewes grazing low-density corn gained the most weight (10.9 kg), those grazing stockpiled fescue lost 1.8 kg and those grazing high-density corn and eating fescue hay in drylot were intermediate (7.7 and 5.9 kg, respectively; P < 0.01). Carrying capacity of both corn density treatments was similar. Stockpiled fescue pasture supported only 20 percent of the carrying capacity of the corn fields (P < 0.01). Grazing corn (both planting densities) resulted in feed costs of 19?/d and 23?/d for the low- and highplanting densities, respectively. Estimated costs for feeding fescue hay were 21?/d. Grazing stockpiled fescue was lowest at 17?/d. In conclusion, winter-grazing standing corn or stockpiled fescue were effective and economical feeding strategies to meet the nutritional needs of gestating ewes.
Sheep & Goat Research Journal. Volume 21, 2006
Browsing of Western Snowberry by Goats and Sheep
Managers of pastures in the northern tallgrass prairie region are faced with incomplete control of aggressive woody plant species, such as western snowberry (Symphoricarpus occidentalis Hook.), due to its high sprouting ability after fire or mowing and the reluctance of managers to use herbicides, which may harm desirable plant species. The objective of this study was to compare browsing preference for western snowberry by goats and sheep as an alternative control method of western snowberry. The study was conducted from 2003 through 2005 at South Dakota State University?s Oak Lake Field Station in eastern South Dakota. Small, fenced plots of native prairie vegetation, infested with western snowberry, were grazed by either sheep or goats for three to five days in late June. Western snowberry plant height, foliar cover, forb foliar cover, and grass foliar cover were measured before and after grazing. During the grazing period, goats reduced western snowberry more than did sheep, reducing plant height 12 percent vs. 0 percent and foliar cover 43 percent vs. 19 percent, respectively (P < 0.10) adjusted for similar stocking rate. Goats also selected forbs, reducing forb foliar cover by 44 percent vs. 28 percent (P < 0.10) for sheep during the grazing period. Goats and sheep selected grass to a similar extent. Goats could be an acceptable alternative to herbicides for western snowberry control. However, managers also should be aware that heavy defoliation of forbs by both species may result in a decrease in desirable plant species.
Stocking Rates on Cultivated Winter Pastures for Meat Goats
Cultivated cool-season pastures are needed to complement rangeland-based goat production in warmer regions of North America, but optimum stocking rates have yet to be determined. To address this question, growing Spanish X Boer doe kids (average 25 kg) were stocked at 0-12.5 head ha-1 from 14 January to 22 April 2002 (366 mm rainfall from October 2001 to April 2002) and 8 January to 23 April 2003 (494 mm rainfall over the same months) on cultivated pastures seeded with annual, coolseason grasses and legumes in north-central Texas, United States. Legumes comprised only 10 percent of the herbage and were less affected by stocking rates than were grasses. Grass biomass increased during the growing season and declined with stocking rate. Herbage fiber concentrations increased and N concentrations decreased with both grass and legume maturity and were not strongly affected by stocking rates. There was an inverse relationship between average daily gains per animal and per area, with the best gains (132 g) per animal at low stocking rates and greatest production (463 g) ha-1 at high stocking rates. Stocking rates indicated that herbage availability appeared to be a greater determinant to animal weight gain than did herbage nutritive value.
Sexual Performance and Reproductive Characteristics of Young Adult Awassi, Charollais-Awassi and Romanov-Awassi Rams
This study was conducted to evaluate the reproductive performance of two-yr-old, sexually na?ve rams of different genotypes. Eight rams of each Awassi (A), F1 Charollais- Awassi (CA) and F1 Romanov-Awassi (RA) genotypes were subjected to sexual performance tests by being individually exposed to two estrous Awassi ewes for five, 20-min periods. Body weight (BW), body condition score (BCS), scrotal circumference (SC) and semen characteristics were recorded every 2 wk for 2 mo prior to sexual performance testing. Awassi rams engaged in more leg-kicking bouts (P < 0.01) than RA rams. Mounting frequency, raising the fat tail of females, and ejaculation rate were greater (P < 0.05) in A than in CA and RA rams. No genotype x test day interactions were detected, however, test day influenced (P = 0.05) ejaculation rate. Rams of the CA genotype had greater BW (P < 0.01) than RA and A. The CA rams had greater SC (P < 0.01) than A rams and higher BCS (P < 0.01) than RA rams. The RA rams had greater (P < 0.05) semen mass motility than A and lower (P < 0.05) percentage of abnormal spermatozoa than A and CA rams. Additionally, semen concentration tended (P < 0.10) to be greater in RA than in A and CA rams. Results of the present study indicate that RA rams tend to have better semen characteristics, while Awassi rams had better sexual performance when mated with fat-tailed females than the CA and RA genotypes, which may necessitate the use of artificial insemination during crossbreeding programs.
The Color of Scoured and Carded Wools: A Comparison of U.S., Australian and New Zealand Wools
Fifty greasy core samples of wool fibers representing various regions of the United States were obtained from Yocom- McColl Testing Laboratories. In addition 50 greasy core sample of New Zealand wool (Soci?t? G?n?rale de Surveillance [SGS]) and 10 greasy core samples Australian Wool Testing Authority (AWTA) were obtained. After scouring, average fiber diameter and clean color were determined. After measurement of clean color, the samples were carded to evaluate its effect on the measured color of the wool. Color measurements of the scoured and the scoured and carded wools clearly indicated that there were differences between the yellowness of the samples. Wools from each country were grouped according to fiber diameter into four groups;
Development and Consumer Acceptance of Pre-cooked Lamb Leg Roasts
The objective of this study was to develop a palatable precooked lamb leg roast. Lamb legs (n = 60) were fabricated into 240 roasts. Roasts were assigned to one of four spice treatments: control (CON), Italian, Mexican, prime rib. After being injected with a 15 percent brine mixture, roasts were smoked to an internal temperature of 63?C, vacuum packaged, and frozen at -10?C. Roasts were thawed and reheated one of three ways (conventional oven, microwave oven, or boiling) and served to a trained sensory panel to determine differences in reheating method. No differences (P > 0.05) were found between reheating methods. The trained panel rated the prime rib spice the juiciest, the most tender, the most flavorful, and the best in overall acceptability. The control treatment (CON) was rated higher (P < 0.05) for lamb flavor, warmed-over flavor, and flavor intensity by trained panelists. Upon completion of trained sensory panel, a consumer panel (n = 199) was served samples of roasts to determine the preferred spice blend. Consumers rated the prime rib spice the highest (P < 0.05) for all palatability attributes and the CON the lowest (P < 0.05). This study indicated the prime rib spice treatment was preferred most often for tenderness, juiciness, flavor, and overall liking by both the trained sensory panel and consumer panel. Therefore, roasts seasoned with the prime rib rub appear to have the most market potential.
Efficacy of Dried Distiller’s Grains with Solubles as a Replacement for Soybean Meal and a Portion of the Corn in a Finishing Lamb Diet
The objective of this experiment was to determine the effects of replacing soybean meal (SBM) and a portion of the corn with dried distiller?s grains with solubles (DDGS) on growth performance, carcass characteristics, and the incidence of acidosis, bloat, or urinary calculi in wethers fed a high-grain finishing diet with soyhulls (SH) as the only source of dietary fiber. Wethers (n = 40) were allotted by weight to ten pens (average lamb weight per pen 43.4 kg ? 0.54 kg). Dietary treatments, SH-CORN-DDGS or SH-CORN-SBM, were assigned randomly to five pens. Diets were balanced to have similar CP (14.6 percent), ME (3.4 Mcal/kg), and calcium:phosphorous (2:1) and were pelleted and delivered through self-feeders. Wethers were observed twice daily for symptoms of acidosis, bloat, and urinary calculi. Feed offerings and feeder contents at trial termination were weighed and DMI was calculated. Gain:feed and ADG were calculated based on weights recorded at initiation and termination of the 64-d finishing period. Growth performance, DMI, and carcass data were analyzed statistically in a one-way analysis of variance with pen as the experimental unit. Average daily gain, DMI, gain:feed, and carcass characteristics did not differ (P > 0.05) between dietary treatments. Wethers did not exhibit symptoms of acidosis, bloat, or urinary calculi regardless of treatment. Dried distillers grains with solubles is a suitable substitute for SBM and a portion of the corn in a finishing wether diet where SH are the only source of fiber.
Development and Consumer Acceptance of Pre-cooked Goat Roasts
The objective of this study was to develop a palatable, precooked goat roast. Goat legs (n = 64) were fabricated into 220 roasts and assigned to one of four spice treatments: control (CON), Italian, Mexican, prime rib. After being injected with a 15-percent brine mixture, roasts were smoked to an internal temperature of 63?C, vacuum packaged, and frozen at -10?C. Roasts were thawed and reheated one of three ways (conventional oven, microwave oven, or boiling) and served to a trained sensory panel to determine differences in reheating method. The trained panel rated roasts boiled lower (P < 0.05) for initial and sustained juiciness and tenderness than roasts reheated in the microwave or conventional oven. The trained panel rated the prime rib spice juiciest, most tender, most flavorful, and the best in overall acceptability. The control treatment (CON) was rated higher (P < 0.05) for goat flavor, warmed-over flavor, and flavor intensity by the trained panelists. Upon completion of the trained sensory panel, a consumer panel was conducted to determine differences in treatments. Consumer panelists (n = 200) were served samples of roasts to determine preferred spice blend. Consumers rated the prime rib spice the highest (P < 0.05) for all palatability attributes and the Italian roasts the lowest (P < 0.05). This study indicated the prime rib spice treatment was preferred most often for tenderness, juiciness, flavor, and overall liking by both trained sensory panelists and consumer panelists. Therefore, roasts seasoned with the prime rib rub appear to have the most market potential.
Corn Supplement for Goats on Summer Rangeland or Improved Pasture
Improved (cultivated) pastures (IP) and supplements are needed to complement rangeland-based goat production in warmer regions of North America during the hot and dry months of June through September. To address this need, growing Spanish X Boer wether kids (average 25 kg) grazing IP (primarily annual legumes and Amaranthus retroflexus) were compared to kids on honey mesquite native rangeland (NRProsopis glandulosa var. glandulosa) with an understory dominated by little bluestem (Schizachyrium scoparium) during the summers of 2002 and 2003 in north-central Texas, United States. Wethers within both IP and NR were supplemented with corn meal at 0 percent, 0.5 percent, or 1.0 percent BW. Herbage biomass in the IP peaked in July, whereas biomass in the NR tended to peak in August. Kids supplemented with 0.5 percent BW corn on the NR had 61percent greater average daily gains (ADG) than unsupplemented animals, whereas those on IP had to be supplemented at 1.0 percent BW corn before showing an increase in ADG (31percent) compared to unsupplemented animals. Unsupplemented wether kids on NR gained only 30.5 percent the ADG of kids fed a balanced feedlot diet (159 g ADG), while kids on IP gained 53.3 percent of those fed a balanced feedlot diet, indicating that neither foragebased system was able to provide the nutrition needed to achieve maximum gain potential. Improved pasture and corn supplement both have potential for increasing wether ADG compared to rangeland during dry, hot summer months.
Sheep & Goat Research Journal. Volume 20, 2005
Seasonal Acceptance of Fourwing Saltbush by Sheep When Crested Wheatgrass is the Alternative
Many sagebrush-grass ranges have been seeded to crested wheatgrass [Agropyron desertorum (Fischer ex Link) Shultes]. These ranges are generally nutritionally inadequate for sheep (Ovis aries L.), except for short grazing periods in the spring and fall. To increase production and diversity, particularly crude protein for late-season grazing, fourwing saltbush [Atriplex canescens (Pursch.) Nutt.] was planted in an existing stand of crested wheatgrass. Quantification of sheep forage preferences on these improved ranges aids in determining the length of the grazing season and the extent to which shrubs provide the supplemental nutrition required. This seasonal grazing study was conducted on a characteristic wheatgrass-saltbush, mixed-range pasture to determine sheep acceptance of fourwing saltbush when crested wheatgrass was the alternative available forage. Sheep preferences for grass and shrub in spring and winter were similar, averaging 84 percent grass and 16 percent shrub. Summer dietary preferences ranged from 69 percent to 93 percent grass and 7 percent to 31 percent shrub. Preference for fourwing saltbush was consistently lower than crested wheatgrass in all seasons. Sufficient amounts of the mixed pasture were grazed to reduce the need for supplemental feed, when compared to crested wheatgrass monoculture. The results of these grazing trials suggest fourwing saltbush can be useful in improving pasture nutrition for sheep in different grazing seasons.
Feedlot Performance and Carcass Characteristics of Lambs Sired by Texel, Romanov, St. Croix or Dorset Rams from Polypay and St. Croix Ewes
Over a 2-year period, crossbred lambs resulting from the mating of Texel (T), Romanov (R), and St. Croix (S) rams with Polypay (P) and S ewes, were finished during the summer and late fall to determine feedlot performance and carcass characteristics. A total of 175 wether lambs of the five genotypes (R x P, R x S, S x S, T x P and T x S) were fed a high-energy diet for an average of 110 d (Experiment 1). Purebred St. Croix lambs weighed less (P < 0.05) at the beginning and end of the finishing period, had the lowest average daily gain (ADG) (P < 0.05), and the lowest Gain:Feed (P < 0.10) of the five genotypes evaluated. All five genotypes produced carcasses with a quality grade ?? Choice. In a subsequent 2-year experiment (Experiment 2), 251 lambs sired by either Dorset or St. Croix rams from the ewes created in Exp.1 were used. Dorset-sired lambs were heavier (P < 0.10) at the end of the feeding period and had greater ADG (P < 0.10) than lambs sired by St. Croix rams. Wether lambs were heavier (P < 0.10), grew faster (P < 0.10) and ate more (P<0.05) feed than female lambs. Lambs from crossbred ewes were heavier (P <0.05) at the beginning and end of the finishing period and grew faster (P < 0.10) than lambs from purebred St. Croix ewes. When Dorset rams were used as the terminal sire, lamb feedlot performance was similar among the five ewe genotypes used in this study. Key words: Lambs, Crossbreeding, Feedlot, Carcass Quality, Carcass Cutability.
Cost of a Maedi Visna Flock Certification Program and the Changes in Productivity and Economic Return
Maedi Visna (MV) has been identified as a common viral infection in Ontario sheep. The Maedi Visna Flock Status Pilot Project (MVFSP) sets a protocol for control and eradication of this disease. A static normative model was designed to measure the economic benefit of such a program. Of the 16 producers enrolled on the program in 2002, 15 cooperated and were surveyed.
Two benefits were identified from being MV free: 1) higher purebred sheep sale prices and 2) improved ewe productivity. The benefits to purebred sheep breeders warrant eradication within sheep flocks. With only a 10 percent improvement in purebred price, even on only 25 percent of lambs sold for breeding stock, a producer should expect to breakeven on the added costs associated with the MVFCP program just shortly after becoming ?A? Status. This outcome was robust for all combinations of flock size, ewe and purebred sheep sale values, and bleeding costs.
Commercial sheep producers did not find the same positive outcome. With low prevalence of the disease, few benefits accrued. Only with prevalence levels over 10 percent with low bleeding costs and large flocks would commercial producers show a reasonable payback period of about six years, and then only with the Monitored Program. Payback would never be reached on the Whole-Flock Program for commercial sheep producers.
Post-weaning Growth and Carcass Traits of St. Croix White and Dorper X St. Croix White Lambs Grazing Pasture During the Dry and Wet Seasons in the U.S. VI
This study was conducted to evaluate post-weaning growth, carcass traits and parasite burdens St. Croix White (STX) and Dorper X St. Croix White (DRP) lambs grazing guinea grass pastures during the wet and dry seasons. Lambs (77 d of age) were placed in guinea grass pastures (0.5 ha) in a rotational grazing system. Fecal egg count (FEC), packed cell volume (PCV) and BW were measured weekly. Lambs were slaughtered at a BW of 30 kg. Carcass weight, fat thickness, rib eye area (REA), KPH and leg circumference were measured. Data were analyzed by SAS procedures. Total rainfall was 647.7 mm and 1495.3 mm for the dry and wet seasons, respectively. Forage availability was 432.5 ? 64.6 kg DM/ha and 1051.0 ? 261.9 kg DM/ha during the dry and wet seasons, respectively. The DRP lambs reached target weight sooner (P < 0.0008) than STX lambs (178.2 ? 6.3 d vs. 210.9 ? 6.7 d, respectively). Average daily gain was higher (P < 0.0002) for DRP than for STX lambs (90.3 ? 1.9 g/d vs. 79.1 ? 2.0 g/d, respectively). Carcass weight was not different (P > 0.10) between breed type (13.5 ? 0.1 kg). The REA of DRP lambs was greater (P < 0.01) than that of STX lambs (9.36 ? 0.19 cm2 vs. 8.63 ? 0.21 cm2, respectively). Fat thickness was greater (P < 0.02) in DRP than in STX lambs (1.92 ? 0.10 mm vs. 1.57 ? 0.10 mm, respectively). Leg circumference was larger (P < 0.03) for DRP than for STX lambs (38.2 ? 0.3 cm vs. 37.3 ? 0.3 cm, respectively). There was no difference (P > 0.10) between DRP and STX lambs in FEC or PCV. Dorper-sired lambs reared under an extensive management system will reach market weight sooner than St. Croix White lambs and can tolerate parasite burdens similar to those found in the indigenous hair sheep in the U.S. Virgin Islands.
Post-weaning Growth and Carcass Traits of St. Croix White and Dorper X St. Croix White Lambs Fed a Concentrate Diet in the U.S. Virgin Islands
Growth and carcass traits of St. Croix White (STX; n = 22) and Dorper X St. Croix White (DRP; n = 18) lambs fed a concentrate ration were evaluated. Starting two weeks after weaning (63 d of age) lambs were fed a commercial diet at 4 percent BW•hd-1•d-1. Lambs were slaughtered at a BW of 30 kg. Carcass weight, fat thickness over the 12th rib, rib eye area (REA), percent KPH and leg circumference were measured. Days on feed was greater (P < 0.01) for STX than for DRP lambs (153.2 ± 6.8 d vs. 118.9 ± 7.4 d, respectively). Total weight gained was greater (P < 0.04) for STX than for DRP lambs (16.1 ± 0.5 kg. vs. 14.6 ± 0.5 kg, respectively). The ADG of DRP lambs was higher (P < 0.01) than that of STX lambs (125.1 ± 4.7 g/d vs. 108.1 ± 4.3 g/d, respectively). Carcass weight was not different (P > 0.10) between breed type (12.6 ± 0.2 kg). The REA of DRP lambs was greater (P < 0.02) than that of STX lambs (10.4 ± 0.4 cm2 vs. 9.0 ± 0.4 cm2, respectively). Fat thickness was not different (P > 0.10) between DRP and STX lambs (1.5 mm ± 0.2 mm). Percent KPH was higher (P < 0.001) in STX than in DRP lambs (3.6 ± 0.3 percent vs. 2.2 ± 0.3 percent, respectively). Leg circumference was greater (P < 0.007) for DRP than for STX lambs (37.3 ± 0.4 cm vs. 35.7 ± 0.4 cm, respectively). Cost of gain was higher (P < 0.05) for STX than DRP lambs (4.08 ± 0.02 S/kg. vs. 3.73 ± 0.02 $/kg, respectively). Sales of DRP resulted in greater (P < 0.03) net revenue than sales of STX in each market. Dorper X St. Croix White crossbred lambs fed a concentrate ration are economically feasible due to lower cost of gain, higher ADG and revenue.
Growth Performance of Barbados Blackbelly, Katahdin and St. Croix Hair Sheep Lambs Fed Pasture- or Hay-based Diets
Two experiments evaluated growth of mixed-sex Barbados Blackbelly, Katahdin, and St. Croix hair sheep lambs raised on pasture or hay-based diets with moderate levels of energy supplementation. In Experiment 1, 36 ewe and wether lambs were allocated to a pasture or pen feeding group in May. Pasture animals rotationally grazed tall fescue pasture, while pen animals were offered chopped alfalfa hay, and both groups were supplemented with corn/soybean meal at 0.75% of body weight. In Experiment 2, 72 lambs were allocated to pen and pasture in April, and provided either a low or high crude protein concentration corn/soybean meal supplement at 1.5% of body weight. Pasture animals were continuously grazed, while pen animals were offered chopped mixed grass hay. In both experiments, starting and final body weights were higher (P < 0.05) in Katahdin than St. Croix and Barbados Blackbelly. In Experiment 1, daily gain was similar between Katahdin (84 g/d) and St. Croix (75 g/d), and higher (P < 0.01) than in Barbados Blackbelly (56 g/d). Daily gain was higher (P < 0.05) for lambs in pens (77 g/d) than for lambs on pasture (67 g/d). In Experiment 2, growth rates were higher than in Experiment 1, and Katahdin (109 g/d) grew faster (P < 0.05) than St. Croix (86 g/d) and Barbados Blackbelly (73 g/d). Growth was not affected (P > 0.10) by forage or supplement type, but wether lambs grew faster (P < 0.05) than ewe lambs. The growth rates in both trials were moderate and produced lambs of medium size, suitable primarily for the Muslim and Hispanic ethnic markets.
Gastrointestinal Parasitism in Hair Sheep and Meat Goat Breeds Grazing Naturally Infected Pasture
Differences in indicators of gastrointestinal parasitism between species, breeds within species, and two grazing systems (goats only) were evaluated in a total of 66 does and 22 ewes (11 animals/breed/management system), representing four goat and two sheep breeds. Animals were either grazed continuously (does and ewes, n=66), or rotationally on 0.4 ha of pre-dominantly fescue pastures (does only, n=22). Fecal and blood samples were collected in 14-day intervals from mid-May until October. Animals were dewormed (ivermectin, sc, 0.3 mg/kg) by breed group when breed composites (five animals/breed) exceeded 1000 eggs/g. Data were analyzed in subsets for species, breed, and grazing management comparisons. Hair sheep had lower mean FEC (376 vs. 669 eggs/g; P < 0.01) and higher mean PCV (31.9 percent vs. 26.5 percent; P < 0.001) than the goats. Within hair sheep, Katahdin had lower FEC (242 vs. 518 eggs/g; P < 0.01) and were dewormed less frequently (2 vs 7) than the Barbados Blackbelly. In goats, Nubian and Spanish (1035 and 865 eggs/g, respectively) had higher (P < 0.01) mean FEC than Myotonic and Pygmy (413 and 359 eggs/g, respectively), and were dewormed five, four, three, and three times, respectively, during the experimental period. Fecal egg counts were similar in goats under rotational, compared to continuous grazing. Hair sheep appeared to be more resistant to parasites than goats, however, differences may have been masked by considerable breed variation within species. The anthelmintic treatment protocol may have prevented breeds from expressing their ability to tolerate gastrointestinal parasites.
Carcass and Growth Characteristics of Wethers Sired by Percentage White Dorper or Hampshire Rams 1
To evaluate the use of percentage Dorper rams as terminal sires in the Upper Midwest, 72 Finn-Dorset-Targhee (FDT) ewes were mated to one of two 3/4 White Dorper-1/8 East Fresian- 1/8 Corriedale (WD) rams and 77 FDT ewes were mated to one of two Hampshire rams in single-sire mating groups. Thirty-seven WD-sired and 55 Hampshire-sired wethers were utilized for the study. All male lambs were castrated by elastration at 1 day of age. Wethers were maintained as a group until slaughtered at a commercial packing plant. Carcass data were collected at slaughter. Hampshire-sired wethers tended to have greater birth weights (4.8 ? 0.14 kg vs. 4.4 ? 0.15 kg; P = 0.06) and had greater adjusted weaning weights (33.4 ? 0.85 kg vs. 30.4 ? 1.01 kg; P = 0.03) than WD-sired wethers. Hampshiresired wethers had greater post-weaning average daily gain (0.36 ? 0.02 kg/day vs. 0.28 ? 0.01 kg/day, respectively; P = 0.0002), greater finished weights (57.8 ? 0.7 kg vs. 51.7 ? 0.8 kg, respectively; P = 0.0001), greater hot-carcass weights (29.1 ? 0.4 kg vs. 26.6 ? 0.5 kg, respectively; P = 0.0001), less fat over the ribeye (0.46 ? 0.02 cm vs. 0.55 ? 0.03 cm, respectively; P = 0.03) and thinner body walls (2.2 ? 0.06 cm vs. 2.5 ? 0.1 cm, respectively; P = 0.001) than WD-sired wethers. Hampshire-sired wethers grew faster and produced leaner carcasses than wethers sired by percentage WD rams.
Lamb Production of Dorper, Katahdin, and St. Croix Bred in Summer, Winter, or Spring in the Southeastern United States
Ewe production traits and ability to breed out of season were compared for the Dorper (DO), Katahdin (KA), and St. Croix (SC) breeds between 2000 and 2005. Sheep were managed on grass pasture and were supplemented with corn/soybean meal and free-choice, trace-mineral mix. Ewes were exposed to rams of their respective breeds in late summer (August/September), winter (December), or spring (April/ May) for 30-day breeding periods. Lambs were weighed at birth and 60 days of age. Pregnancy and lambing rates and litter birth weight were greater for all breeds bred in winter and lowest in spring. Pregnancy losses were greater and birth weights reduced for DO and KA ewes less than two years of age bred in the spring compared with other seasons. Birth weights of lambs were not affected by season, but weaning weights were greatest for all breeds when ewes were bred in summer. Relative efficiency at weaning (kg of lamb produced/kg ewe weight) was greatest for summer-bred ewes and greatest for KA compared with DO and SC ewes. In summary, DO, KA, and SC ewes are capable of out-of-season breeding in Arkansas. However, relative efficiency and weaning weights were lowest for spring-bred ewes and fertility of yearling ewes of all breeds was reduced during spring breeding.
Postweaning Performance of Hair and Wool Sheep and Reciprocal-crosses on Pasture and in Feedlot
Lambs from three diallel-mating plans (Dorset-St. Croix, n=140; Rambouillet-Gulf Coast, n=80; Katahdin-Suffolk, n=78) and a terminal-cross mating plan (Suffolk rams mated to Dorset, St. Croix and reciprocal-cross ewes, n=100) were used to evaluate postweaning grazing performance of traditional meat breeds and tropically adapted breeds of sheep.
Tropically adapted breeds generally had lower postweaning performance than wool breeds in both grazing and feedlot management with the exception that purebred Katahdin and Suffolk were comparable in gain on bermudagrass. Tropically adapted x wool breed lambs were generally intermediate between the parental purebreds except in the Katahdin x Suffolk diallel where there was an indication of heterosis for feedlot ADG and possibly pasture ADG. In general, all lambs performed poorly on forages compared to performance on mixed diets in feedlot. These results indicated a consistent advantage in direct breed effects for wool breeds over tropically adapted breeds in feedlot management systems. The results also suggest that there is little expression of genetic effects in sheep managed on forages, although direct effects for heat adaptation in tropically adapted breeds may compensate for the superior direct breed effects for growth in the wool breeds under summer grazing.
Sheep & Goat Research Journal. Volume 19, 2004
Special Edition: Predation
Predation and Livestock Production Perspective and Overview
Predation (a mode of life in which food is primarily obtained by killing and consuming other animals) is a purely natural phenomenon, but it is a problem when the predator becomes too abundant or it is unacceptable for humans to share individuals of particular species of prey. Predation has likely been a problem since domestication and continues to be a problem which must be dealt with today. Although much of the focus in this compilation of papers is the livestock industry, predation may also be of concern with respect to wildlife species or household pets. The larger predator species may also constitute a direct threat to man. Some predator species (especially wild or feral swine and coyotes) may also interfere with other agricultural endeavors through destruction of fences, damaging crops, or the threat of spread of disease (Sewart et al., – this issue). Predation management with one goal in mind (i.e., protection of sheep) may also have spin-off benefits for other species as well (Shwiff and Merrell, Allen and Fleming, Shwiff and Bodenchuk, this issue).
Economic Impact of Sheep Predation in the United States
Though accounting for less than 1 percent of U.S. livestock industry receipts, sheep and goat operations are still important to the economies of several states in the Southern Plains, Mountain States and Pacific regions. Revenues from sales of lambs and culled ewes amount to more than three-fourths of the total receipts in the sheep industry. However, nearly 4 percent of the animals in the sheep industry are lost each year. Most of this loss is from predation. Predators include coyotes, domestic dogs, big cats, foxes and bears, and eagles. Predator losses are concentrated in the Southern Plains, Pacific States and Mountain regions, due to a high concentration of both sheep and predators in these regions.
Most previous studies have looked at the direct loss from predation. We used the Impact Analysis for Planning (IMPLAN) procedure to construct an input-output (I-O) model of the 10 USDA farm production regions to look at some of the indirect effects associated with predation. The direct value of all sheep and lambs lost due to predation for 1999 was simulated using this I-O model and the regional economic impact evaluated. The simulated impact of predator losses on the U.S. sheep industry showed that a $16 million direct loss in sheep and lambs due to predation results in a more than $12 million additional income loss over the rest of the economy. The economies of the Mountain States, Southern Plains and Pacific were most affected.
Key Words: Sheep, Lamb, Predators, Economic Impact
The History of Federal and Cooperative Animal Damage Control
The predecessor of the Wildlife Services program within the U.S. Department of Agriculture, Animal and Plant Health Inspection Service, was founded by C. Hart Merriam in 1885 with a Congressional appropriation of $5,000. These funds were used to organize a Section of Economic Ornithology as part of the Entomology Division of USDA. Merriam immediately hired longtime friend A. K. Fisher to be his assistant and the two shared a clerk. The new Section proved to be so popular with farmers and politicians that the Congress created a separate Division of Economic Ornithology and Mammalogy in 1886. The Commissioner of Agriculture stated that the principal effort of the Division would be to educate farmers about birds and mammals affecting their interests, so that destruction of useful species might be prevented. One of the first publications dealt with the introduction of the English sparrow into the United States.
Merriam and his assistants began to collect data on the geographic distribution of various birds and mammals of economic importance. “Economic” was gradually dropped from the organization’s title, and in about 1890, the title of the Division was changed to the Division of Ornithology and Mammalogy. Early studies detailed the life histories and impacts of jack rabbits, ground squirrels of the Mississippi Valley, and pocket gophers. In addition, field experiments on the control of prairie dogs in Texas and New Mexico were initiated. Merriam and others soon promoted another change in the title of the Division to the Biological Survey, arguing that the name was more apt, and in 1896, the Division was renamed. In 1905, the name was changed again to the Bureau of Biological Survey and this title remained as long as the program was with the Department of Agriculture.
Merriam’s dedication to field surveys never wavered, even though it brought him into constant conflict with various Congressmen who did not see the practical value of investigating animals in Canada and Mexico. Merriam insisted that the information was needed to help the farmers in the United States. Nevertheless, his agency was known by some as the “Bureau of Extravagant Mammalogy,” and in 1907, several Congressmen attempted to abolish the Bureau’s appropriation. In the end, the effort failed, thanks in part to President Theodore Roosevelt. Roosevelt expressed his pleasure at the outcome with a characteristic note to Merriam that read “Bully for the Biological Survey.
Key Words: ADC, Coyotes, Education, History, Predation, Rodents, Wildlife Services
Status and Management of Coyote Depredations in the Eastern United States
The populations of coyotes (Canis latrans) have increased dramatically in the eastern United States since the early 1900s (Hilton, 1978; Chambers, 1987; Hill et al., 1987; Witmer and Hayden 1992). The expansion of the coyote range into eastern North America has been summarized by Parker (1995) and characterized as two distinct geographical events: 1) the northern front moving across southern Ontario and the Great Lakes region and 2) the southern front colonizing the southeastern United States from Arkansas and Louisiana. These two fronts expanded throughout the northeastern and southeastern United States during the 1960s and 1970s, finally converging during the mid 1980s in the central Appalachian mountains of Virginia and West Virginia. Upon their arrival, eastern coyotes, like their western counterparts, began killing livestock. There has been concern that coyote depredations in the eastern United States could cause significant impacts on sheep and other livestock industries (Slate, 1987; Witmer and Hayden, 1992; Witmer et al., 1995). Other authors have suggested that coyote predation is an important contributing factor in the decline of the American sheep industry (Terrill, 1986; Hilton, 1992).
Coyote depredations on livestock in the eastern United States have been documented by several authors (Witmer and Hayden, 1992; Witmer et al., 1995; Tomsa and Forbes, 1989). The USDA National Agricultural Statistics Service (NASS) completed surveys of “Sheep and Goat Predator Loss” during the years 1990, 1994, and 1999. Similar surveys of “Cattle Predator Loss” were made in 1991, 1995, and 2000. These nationwide surveys were completed during the final phases of coyote range expansion in the eastern United States and as coyote depredations in the east began to increase. During the 1990s, the USDA APHIS Wildlife Services (WS) programs in Virginia, West Virginia, and Ohio initiated programs designed to assist producers experiencing livestock depredations by coyotes. The WS program documents livestock losses, requests for assistance, and management activities through its Management Information System (MIS). WS uses the MIS system to produce annual reports on coyote depredation management activities. The NASS surveys and WS reports have not been analyzed on a regional basis or in the context of the range expansion of the coyote in the eastern United States. This paper reviews these data and examines the effectiveness of WS programs aimed at managing coyote depredation on livestock in the eastern United States.
Key Words: Coyote, Sheep, Cattle, Depredation
The Coyote in the Edwards Plateau of Texas — an Update
In the early 1900s, organized predator control was initiated to remove coyotes and wolves from the sheep- and goat-producing areas of Texas. Operations were begun in the Edwards Plateau, the largest area of sheep concentration. The Edwards Plateau and, to a lesser extent, portions of other adjoining ecological areas presently account for 18% (1.2 million head) of the sheep and lambs and 85% (1.2 million head) of the goats in the United States (Texas Agriculture Statistics Service, 2004). These numbers are down in both actual numbers and as a percent of the national flocks. It is important that the industries be protected and preserved. The inventory and distribution of sheep and goats by counties in 2003 is reflected in Figures 1 and 2. The Edwards Plateau itself encompasses about 24 million acres of “Hill Country” in West-Central Texas comprising all or portions of 37 counties (Fig. 3). By the 1920s, many of the interior Edwards Plateau counties were considered to be free of coyotes and wolves.
In 1950, there were 33 counties covering nearly 24,000,000 acres, which were considered to be coyote free (Fig. 4). This area remained virtually void of coyotes for several decades until their encroachment began in the 1960s. This process has been described by several authors (Caroline, 1973; Shelton and Klindt, 1974; Hawthorne, 1980; Nunley, 1985; Nunley, 1995a). The purpose of this paper is to review and update the progress of the re-establishment of coyotes into the Edwards Plateau of Texas, since that reported by Nunley (1995a). This area is historically and currently unique due to its unsurpassed intensive level of coyote control over an extensive area.
Coyote Predation Management: An Economic Analysis of Increased Antelope Recruitment and Cattle Production in South Central Wyoming
In 1999, a project was implemented for the protection of antelope fawns in two areas of Carbon County, Wyoming. The project was funded by the Wyoming Animal Damage Management Board (ADMB) for the benefit of two antelope areas that were having trouble rebounding to their normal population levels after the severe winters of 1991 and 1992. While the Wyoming ADMB project’s main focus was on enhancing pronghorn antelope fawn recruitment, the benefits of coyote population management could have “spillover” benefits to cow/calf producers in the coyote removal areas.
With the decline of the value of coyote fur in the late 1980s, coyote populations have increased in many areas of Wyoming, including ADMB area 63 and ADMB area 55, the two geographic areas in the study (Merrell and Shwiff, in review). ADMB area 61, another geographic area, was the control site. At the ADMB two predator management sites, there are, on average, 4,095 cows giving birth every spring. Since the decline of the sheep industry in these areas in the mid-1970s, no significant coyote management had been conducted. A study on the relationship of coyotes to mule deer fawn recruitment, done on and around area 63 in 1976-79, estimated the area’s coyote population at 1 coyote/20.6 square miles (Springer and Wenger, 1981). Population data from the ADMB project for pre-treatment coyote populations in 1999 were 1 coyote/2.2 square mile, a nine-fold increase (Merrell and Shwiff, in review).
Prior to 1972, coyote populations had been suppressed by the use of broad-based poisons such as 1080, thallium and strychnine. After the ban on poisons, coyote populations continued to be suppressed by people hunting and trapping for fur. Many cow/calf producers who historically had been operating in low-coyote population densities, felt that coyote predation on calves was not at a level to cause concern. Our study suggests that these coyote populations should be a serious economic concern to both the producer and the consumer.
Key Words: Antelope, Coyote, Cost-Benefits, Economics, Predation Management
Feral Swine Impacts on Agriculture and the Environment
More than 30 species of exotic free-ranging mammals have become established in the United States since European colonization (De Vos et al., 1956; McKnight, 1964; Roots, 1976). These species often become serious economic pests and can have grave consequences on their host environments (Cottam, 1956; De Vos et al., 1956; Mayer and Brisbin, 1991). True wild pigs (Suidae) are not native to the United States. Only the collared peccary (Tayassu tajacu; Tayassuidae) that inhabits the southwestern and south-central parts of the United States is native (Mayer and Brandt, 1982; Mayer and Wetzel, 1986). Feral swine (Sus scrofa) in the United States have originated from varieties of domestic swine, Eurasian wild boar, and their hybrids (Jones, 1959; Wood and Lynn, 1977; Rary et al., 1968; Mayer and Brisbin, 1991). Domestic swine were introduced to the United States as early as 750-1000 A.D. during the settlement of the Hawaiian Islands (Towne and Wentworth, 1950; Joesting, 1972; Smith and Diong, 1977). Christopher Columbus introduced domestic swine to the West Indies during the 1400s, where they proliferated and became pests. In the 1500s, Spanish explorers, such as DeSoto and Cortez, were the first to bring domestic swine to the United States mainland (Towne and Wentworth, 1950; Beldon and Frankenberger, 1977). By the 1960s, domestic swine and Eurasian wild boar were established in >20 states (McKnight, 1964). Swine introductions have intentionally or accidentally occurred by a variety of means, including: 1) translocation to establish populations for hunting, 2) escapees from shooting preserves or confinement operations, 3) avoidance of capture by domestic pigs in free-ranging livestock operations, 4) abandonment by their owners, and 5) dispersal from established feral populations (Gipson et al., 1997; Witmer et al., 2004).
Feral swine are the most abundant free-ranging, exotic ungulate in the United States (McKnight, 1964; Decker, 1978) and have become widespread because of their reproductive potential and adaptability to a wide range of habitats. Like domestic swine, litter size depends on the sow’s age, nutrition, and time of year. Feral swine are capable of producing two litters per year with average litter size varying from 4.2 to 7.5 piglets (Taylor et al., 1998), but up to 10 piglets can be born during ideal conditions (Conquenot et al., 1996). Mayer and Brisbin (1991) and Mackey (1992) report feral swine populations in 23 states. A Southeastern Cooperative Disease Study (1994) and Nettles (1997) point out an additional 16 states with feral swine populations. An estimated population of 4 million feral swine currently occur in the United States (Pimentel et al., 2000) with the largest populations inhabiting Texas (1 to 1.5 million; Pimentel et al., 2000), Florida (>500,000; Layne, 1997), Hawaii (80,000; Mayer and Brisbin, 1991), and California (70,000; Barrett, 1993). Since 1965, feral swine have expanded their range from 15 (26%) to 45 (78%) of the 58 California counties (Frederick, 1998). Feral swine populations continue to increase (Gipson et al., 1997) because they possess the greatest reproductive potential of all free-ranging, large mammals in the United States (Wood and Barrett, 1979; Hellgren, 1999) and because of the absence of large native predators (e.g., mountain lion (Felis con-color) and wolves (Canis lupus) over much of the area occupied by feral swine. In southwest Florida where feral swine and a large predator coexist, feral swine is the most common food item (42%) in Florida panther (F. c. coryi) scats (Maehr et al., 1990), which may suggest that the presence of a large predator helps regulate feral swine density and associated damage.
Key Words: Depredation, Disease, Eurasian Wild Boar, Feral Swine, Sus scrofa, Wildlife Damage Management
Managing Wolf Depredation in the United States: Past, Present, and Future
With the successful recolonization and reintroduction of wolves (Canis lupus) in parts of the western United States (Bangs and Fritts, 1996; Bangs et al., 1998) and the natural expansion of wolves in the upper Midwest (Fuller et al., 1992; Thiel, 2001), managing conflicts between wolves and livestock is a growing issue for livestock producers, resource professionals, and the general public (Mech, 1996). Unlike the coyote, (Canis latrans) where a great deal is known regarding the biology and ecology of depredation and methods for managing it (Knowlton et al., 1999), very little is known regarding patterns and processes of wolves preying on livestock and effective ways to mitigate this conflict. Understanding the ramifications of growing wolf populations for livestock production and successfully managing these problems will require knowledge of depredation patterns, wolf ecology, livestock husbandry, and the effectiveness of different tools and techniques to manage wolves. As wolf populations expand into more agricultural areas (Mech et al., 2000) such knowledge will become increasingly important.
Here historic records were compared to current data on wolf depredation rates and wolf management techniques relative to the wolf’s status on the endangered species list. The objectives were to synthesize the history of wolf depredation and management, present current data of wolf impacts on livestock, and speculate on the future management of wolves so that producers can consider the ramifications of a growing wolf population and possible mechanisms for decreasing the threat.
Compensation Programs in Wyoming for Livestock Depredation by Large Carnivores
Common law in America, which has been continually reinforced in the courts of the United States, holds that the people of the state own the wildlife within its boundaries. No person or entity holds absolute property rights to wildlife regardless of the ownership of the land on which the animal is found. The courts have construed that since wildlife belongs to everyone, everyone must share in its keep. As a result of this interpretation, courts have ruled the government, both state and federal, is immune from liability for damage caused by wild animals, unless the government waives its sovereign immunity and voluntarily assumes liability.
The federal government has long invoked its sovereign immunity from liability for damage caused by species managed under federal law, such as migratory waterfowl, passerine birds, and those species listed as threatened or endangered, such as grizzly bears and gray wolves. In addition, many states have traditionally invoked their sovereign immunity from liability for damage caused by wild animals. As an example, the state of South Dakota does not accept monetary liability for damage done by wildlife. Conversely, some states, such as Wyoming, Utah, Washington and Idaho, have waived their sovereign immunity to a limited degree and assumed liability for some types of damage caused by some types of wild animals.
After a century of persecution that resulted in large scale population reductions, large predator numbers have increased over much of their former ranges in North America. Predators such as wolves, cougars and grizzly bears are making a comeback in parts of the West. The comeback is largely due to a variety of changing societal values about predators that have resulted in reduced control campaigns. Along with the increase in predators, predator compensation programs have evolved in some jurisdictions. Currently, fourteen states and four Canadian provinces have government administered programs to reimburse livestock owners for losses caused by some predators. In addition, Defenders of Wildlife, a private conservation group, reimburses livestock producers for losses caused by grizzly bears in two western states and wolves in three western states. Most programs pay for losses caused by only the large predators (black bears, grizzly bears, cougars, and wolves) even though in most states smaller predators, such as coyotes or golden eagles, cause a far more significant monetary loss to the livestock industry. This industry is important, and in some instances critical, to the rural infrastructure and local economies of Wyoming.
Key Words: Compensation, Predators, Livestock
Direct, Spillover, and Intangible Benefits of Predation Management
Predation management is a controversial and often misunderstood reality of livestock management. Few on either side of the argument would believe that some sort of management is not necessary to limit livestock losses. Opposition to the lethal removal of predators characterizes most debates. While most of the opposition reflects a moral opinion about the manner in which people relate to the natural world, opponents of lethal control often argue that control is not economically justified.
Simple economic justification would require that benefits of predation management outweigh the costs. If the only goal of predation management were to be economically efficient, minimization of costs would be one of the primary objectives; however, current predation management philosophies focus on minimum disruption to natural processes. These include focusing lethal management of offending individuals and populations, and using methods (such as aerial hunting) that are expensive but highly selective and humane. Boardman et al. (1996) discuss that the objective of minimizing costs is the same as maximizing net benefits. The costs of management, while important, play a minor role in the selection of management strategies.
Costs of management include direct expenditures by producers for management programs, governmental expenditures for management and compensation programs, producer and governmental costs associated with preventing predation, and societal values associated with the predators removed. Costs of predation management programs are usually easier to quantify, can have significant variance and typically are concentrated to a few individuals, while the benefits are dispersed among many. For this reason, the authors intend to focus on the benefits of predation management programs.
Key Words: Predation Management, Economics, Benefits, Costs, Livestock Protection
Indirect Effects of Carnivores on Livestock Foraging Behavior and Production
Direct effects of predation (i.e., killing of animals) can result in significant economic losses to livestock producers. A recent publication by the USDA, Wildlife Services (2002) identified the following losses: (1) livestock losses attributed to predators, predominantly coyotes (Canis latrans), reach about $71 million annually; (2) cattle and calf losses to predators in the United States totaled 147,000 head during 2000. A National Agricultural Statistics Service (NASS) study valued these losses at $51.6 million; (3) sheep and lamb losses to predators in the United States totaled 273,000 in 1999. A NASS study valued these losses at $16.5 million; (4) In Arizona, New Mexico, and Texas, the three major goat-producing states, 61,000 goats and kids were lost to predators in 1999. A NASS study valued these losses at $3.4 million. Although direct losses of livestock due to depredation are often conspicuous and economically significant, they likely underestimate the total loss to producers because they do not consider indirect effects of carnivores as a result of livestock being exposed to the threat of predation without being killed.
Laundr et al. (2001) suggested that behavioral responses by prey species to impending predation might have more far-reaching consequences for ungulate behavioral ecology than the actual killing of individuals by predators. Potential negative, indirect impacts associated with the mere presence of predators include, but are not limited to, increased vigilance and reduced foraging efficiency by prey species, and being forced by predators to forage in subopti-mal habitats that contain lower quality or quantity of nutrients, and higher levels of toxins. Moreover, overuse of and lowered carrying capacity in suboptimal habitats could contribute to resource degradation (e.g., overgrazing in marginal habitats, increased erosion and sedimentation) and lower producer profits due to declines in livestock production (e.g., weight gain, body condition, lamb or calf crop). Thus, indirect impacts of predation may have negative impacts on the ecological integrity of the land, as well as negative impacts on personal, local, and regional economies that depend on livestock production. However, there is little or no published information that addresses indirect effects of carnivores on domestic ungulates.
The purpose of this paper is to discuss how the mere threat of predation might influence foraging efficiency and vigilance, diet and habitat selection, skin-gut responses, and social behavior in wild and domestic ungulate prey species. Because there is little or no published information on domestic ungulates concerning these subjects, we rely heavily on wild ungulate studies that have attempted to quantify or qualify the indirect effects of predation. Our aim is to use the wildlife literature as a springboard to stimulate discussion among producers, wildlife damage management professionals, and researchers regarding ways to quantify and address the indirect effects of carnivores on domestic ungulates. We first discuss the evidence from the wildlife literature that supports indirect effects of carnivores on wild ungulates, and then relate that evidence to its potential implications for domestic livestock foraging behavior and production.
Key Words: Cattle, Coyotes, Deer, Elk, Indirect Effects, Predation, Sheep, Wolves
Livestock Depredations by Black Vultures and Golden Eagles
Black Vulture Biology
There are two species of vultures common in North America, the turkey vulture (Cathartes aura) and black vulture (Coragyps atratus). In many localities in the United States, vultures are called “buzzards.” The turkey vulture specializes in locating and eating carrion. Black vultures also subsist principally on carrion, but at times this species is predatory. Thus, for livestock producers, the black vulture is the species of concern.
Key Words: Black Vulture, Depredation, Golden Eagle, Livestock
Non-lethal Alternatives for Predation Management
The ethical milieu in which wildlife biologists and livestock producers work continues to change as the concepts of environmentalism and animal rights and welfare have become introduced and normalized (Singer, 1975). The American public, including livestock producers, are mired within a typically human psychological quagmire of having a high demand for benefit, but a low tolerance for cost ? that is, economic forces. Americans tend to demand a cheap, reliable food supply, while simultaneously demanding the existence of animals that, through predation activities, drive up production costs. Ironically, members of the urban public who may find fault with food and fiber production practices are also the customers on which livestock producers are dependent.
In the United States, predation management has evolved from an attempt to eradicate or limit predator populations to the application of focused approaches for minimizing the damage done by predators. For coyotes, very large scale population suppression (using 1080), was restricted and sometimes apparently ineffective (Wagner, 1988). Other authors could find little correlation between the number of coyotes removed and the number of sheep kills at a California ranch (Conner et al., 1998). Further studies suggested that at least in some areas, dominant territorial coyotes are responsible for most sheep predation but typical lethal control methods tend to bias capture toward coyotes that are less likely to be livestock killers, thus, typical lethal methods such as trapping, snaring, and using M-44s are sometimes inefficient for solving depredation problems (Sacks et al. 1999, Ble-jwasetal. 2002).
Key Words: Bear, Coyote, Depredation, Lion, Livestock, Management, Non-lethal, Predation, Predator, Wolf
Use of Livestock Guarding Animals to Reduce Predation on Livestock
Predation by coyotes (Canis latrans), domestic dogs, mountain lions (Felis con-color), black bears (Ursus americanus), red foxes (Vulpes vulpes), golden eagles (Aquila chrysaetos), and bobcats (Felis rufus) has been a major problem faced by domestic sheep, goat (NASS, 2000), and cattle (NASS, 2001) producers. Predators were reported to kill 273,000 sheep and lambs (NASS, 2000) and 147,000 cattle and calves (NASS, 2001) in the United States, and 61,000 goats in Arizona, New Mexico, and Texas (NASS, 2000) during either 1999 or 2000. Several methods, including the use of livestock guarding dogs, llamas, and donkeys, have been used to reduce these mortalities (Andelt, 1996, 2001). In this paper, I summarize use and effectiveness of livestock guarding animals for reducing predation on domestic sheep and goats. Recent reviews of livestock guarding animals are provided by Smith et al. (2000) and Rigg (2001).
Key Words: Donkeys, Guarding Animals, Guarding Dogs, Livestock, Llamas, Predation
Predacides for Canid Predation Management
Throughout the livestock industry in the western United States, control of canid predators was considered to be of considerable importance to the livestock industry, especially to sheep producers, who suffered high losses from coyotes and wolves. In the 19th century, the demand for predator control was communicated to Congress and the western state assemblies, with the result that predator control was provided in western states by the Federal Bureau of Biological Survey in cooperation with state agencies, and by trappers hired by stockmen. Steel traps and poisons were the principal methods used for predator control during the early years of the program. Historically, predacides have been used in the United States primarily to control wolves, coyotes, and red foxes that prey on livestock. Strychnine was employed in the late 1800s and early 1900s to collect wolf carcasses (Quaife, 1973). Strychnine drop baits were employed for coyote and fox control through the 1960s. Drop baits consisted of strychnine tablets put in small pieces of perishable fats then placed around unpoisoned decoy carcasses (Robinson, 1962). Meat baits impregnated with a lethal agent, either thallium sulfate or Compound 1080, were used between 1937 and 1972 (Robinson, 1942). Currently, three predacides are available for use in controlling coyotes, foxes, wild dogs, and arctic fox. This paper will provide a description of these toxicants and the current status of their use in predator control in the United States.
Key Words : Coyote, Compound 1080, Cyanide, Livestock Predation, Predacide, Toxicant
Selective Targeting of Alpha Coyotes to Stop Sheep Depredation
Research to find more effective and socially acceptable solutions of managing coyote (Canis latrans) depredation has been ongoing for many years. The primary objective is to develop strategies that effectively reduce losses, not simply reduce coyote numbers. An important step in solving such conflicts is to clearly define the problem. In this case, it is important to know which coyotes are most likely to kill sheep and when and where their depredation is greatest. For a control strategy to be effective, it must be appropriate to these three defining characteristics. The hardest of these questions to resolve has been determining if some coyotes are more likely to kill livestock than others and, if so, whether these animals can be relatively more difficult to remove than the others. While the conventional wisdom of trappers supports the existence of particular sheep-killing coyotes, it is another matter to demonstrate that they in fact occur and to explain why.
This paper is a review of our current state of knowledge about the coyotes that kill livestock, particularly sheep, and methods that can be used to target them. The important research findings upon which this is based will be discussed. The main thrust of the paper will deal with a series of studies done in California between 1993 and 2002. These were undertaken jointly by the National Wildlife Research Center (USDA/Wildlife Services) and the University of California at Berkeley. These studies represent the most intensive investigation to date of predation ecology of coyotes in the presence of sheep. In addition, future research needs will be discussed. This review will illustrate the importance of first developing an understanding of the problem before testing methods to alleviate it, that may be inappropriate.
Key Words : Calling, Coyotes, Depredation, Sheep
Using Genetic Analyses to Identify Predators
Coyote and dog depredation account for much of the economic losses to livestock in the United States (National Agricultural Statistical Service, 2000, 2001). However, depredation by other species (such as members of reintroduced wolf populations) can be more socially and politically contentious. Predators are often elusive and attacks on livestock are not often witnessed but the species of predator causing stock losses can sometimes be ascertained from evidence near the carcass (such as scat or hair), the attack pattern, or size and spacing of bite wounds. However, these species assignments can be subjective and may be influenced by the experience level of personnel, the condition of the carcass, and knowledge of previous predation history at the site. Variation among conspecific predators in attack pattern, and inter-specific overlap in those patterns, may be another complication to accurate predator species identifications. There are wide ranges in accuracy of identifying species based on scat morphology (Far-rell et al., 2000). Variation in individual feeding preferences (Fedriani and Kohn, 2001) may also complicate accurate species identification from scat. Sociological considerations also may influence results. For example, local or regional compensation schemes may unintentionally result in biases in predator species identification (Cozza et al., 1996). Using common field methods, the accurate identification of the gender of a predator responsible for a specific predation event is unlikely. Likewise, although there may be assumptions about which specific individual was responsible for an attack on livestock, those assumptions may not be based on any concrete data. Clearly, an unambiguous method to determine the predator species would remove identification biases. A method to identify the specific individual responsible for kills would benefit our understanding of predation and would be useful in certain situations. Both methods, even if used strictly in research situations, might ultimately result in improved approaches to minimize livestock losses to predation.
Key Words: Coyote, Forensic, Genetic Analysis, Microsattelite, mtDNA, Predation
Economic Impact of Protected Large Carnivores on Sheep Farming in Norway
Norway has historically been a stronghold for carnivore predators. Today there are four protected carnivore species, brown bear (Ursus arctos), wolverine (Gulo gulo), wolf (Canis lupus) and lynx (Lynx lynx), together with the golden eagle (Aquila chrysaetos). The carnivore populations were significantly reduced, and wolves and bears almost eradicated nationally during the end of the 19th and the beginning of the 20th centuries (Ministry of the Environment, 1992; 1996-97). Today, the species are protected, and management calls for restoring demographically and/or genetically viable populations (Ministry of the Environment, 1996-97). Another proposal is to view Norwegian management goals and responsibilities in accordance to the Bern Convention in combination with those of Sweden and Finland, i.e. shared-predator populations for the Nordic countries (Nordic Farmers Central Council, 1988). The principle has recently been introduced by the authorities for management of wolves in Norway, defining viability based on a common Norwegian-Swedish population.
The suitability of the Norwegian environment for large predators is partly due to its extensive land resources and rugged topography. The soil is generally poor and the area of agricultural land limited. However, due to the Gulf Stream, the climate is wet and relatively mild and well suited for production of grass and herbs. Grazing plants are found throughout the country?s mountains and forests and constitute the basic forage for wild ungulates, herded domestic reindeer and livestock. The production systems have traditionally been of utmost significance for inland settlement and development of the local economy. In post World War II times, the national agricultural policy has supported the development of the systems by protecting the market from foreign competition and by providing relatively generous direct support.
Key Words: Rural Economics, Sheep Farming, Carnivore Management, Depredation, Predator Loss, Norway
Review of Canid Management in Australia for the Protection of Livestock and Wildlife – Potential Application to Coyote Management
Australia has two introduced canid species ? European red foxes (Vulpes vulpes) and wild dogs (which include dingoes, Canis lupus dingo, feral domestic dogs C. l. familiaris and their hybrids). Foxes were introduced into mainland Australia in the 1860s and quickly spread (Rolls, 1984; Jarman 1986). This dispersal and establishment is believed linked with the introduction and spread of European wild rabbits (Oryctolagus cunniculus) (Saunders et al., 1995). Except in Tasmania, where previous introductions appear to have been unsuccessful, and in northern Australia, where the climate is unsuitable and rabbits are essentially absent, foxes have become established throughout in virtually all habitats including urban and residential environments (Saunders et al., 1995). Within decades of their introduction, legislation was enacted proclaiming them as pests to agriculture, and more recently, as a key threatening process to endangered small mammals (NSW National Parks & Wildlife Service, 2001). This status has been enshrined in subsequent legislation and strengthened by virtue of foxes being an introduced pest species rather than a native animal.
Dingoes are thought to have arrived in Australia from Southeast Asia about 5000 years before present (Corbett, 1995a). A number of reports have reviewed the origins, ecological significance of dingos, and their morphological and genetic relationship to domestic dogs. Interested readers are referred to Newsome et al. (1980) as one example. Like foxes they are also found in virtually every habitat across the Australian continent and are absent from Tasmania (Fleming et al., 2001). However, because of their longer association with Australia, they are often regarded as a ?native? species (Davis, 2001). Wild domestic dogs have been present since the first European settlement in 1788 (Fleming et al., 2001) and hybridization with dingoes has been occurring ever since (Corbett, 1995a, 2001). Despite the native status of dingoes, all wild dogs and foxes are regarded and managed as pests on agricultural lands, i.e. outside of conservation areas. Pure dingoes alone are afforded legislative protection in areas set aside for conservation (Fleming et al., 2001; Davis and Leys, 2001) yet feral dogs and hybrids effectively enjoy the same legislative protection in conservation areas as dingoes, because they cannot be managed separately.
Keywords : Canid, Coyote, Dingo, Management, Predation, Sheep, Toxicant
Sheep & Goat Research Journal. Volume 18: 2003
Interrelationships of Traits Measured on Fine-wool Rams During a Central Performance Test
A pooled correlation analysis was conducted to estimate the relationships between all traits measured on fine-wool rams (n = 505) during three central performance tests (2000 – 2002). Introduction of minimum initial weight levels (for certification) was expected to have an effect on previously reported significant correlations. In addition to the reported traits, several other traits (measures of variability in fiber diameter, average fiber curvature and variability, for example) that have not previously been reported were included in the analysis. The correlation coefficients calculated are expected to assist breeders to better understand the consequences of their actions when selecting for individual traits. Observed differences between core and side sample average fiber diameters were not highly correlated with any other traits currently measured on the test. Average fiber curvature was not highly correlated with any measure of average fiber diameter but was negatively correlated with several important production traits which may have serious negative consequences for breeders who are selecting for or trying to maintain small crimp. Finally, older rams were shown to be at a disadvantage in the test because age is antagonistically correlated with most of the traits used to evaluate the rams.
Key words: traits, rams, central performance test
Effects of Supplementing Polyethylene Glycol to Goat Kids Grazing Sericea Lespedeza and Early Post-weaning Nutritive Plane Upon Subsequent Growth
Forty-eight Boer x Spanish doelings (4 mo of age, 20.9 + 2.35 kg) were used to test effects of polyethylene glycol (PEG) supplementation of grazed sericea lespedeza and early post-weaning nutritive plane and growth rate on subsequent performance with a concentrate-based diet fed in confinement. Treatments were: Barn, with goats kept in individual pens for the 24-wk trial and fed a 70% concentrate diet (17% CP, 69% TDN) free-choice, C, and PS, with two groups of eight doelings per group for each treatment. In the first 6 wk (Phase 1), C and PS groups grazed 0.4-ha lespedeza paddocks (two paddocks and groups per treatment) and were group-supplemented with 88 g/d per animal of concentrate without (C) or with (PS) an additional 25 g/d per animal of PEG. Because of limited rainfall in Phase 1 and the resultant low availability of growing forage, in Phase 2 (6 wk) treatments were changed in a manner thought to increase differences in BW and ADG between C and PS that developed in Phase 1. In Phase 2, C groups resided in two 1-ha paddocks dominated by crabgrass, whereas PS groups grazed two previously ungrazed 1-ha lespedeza paddocks and were supplemented with 1.5% BW of the Barn diet. In Phase 3, the final 12 wk, all doelings consumed ad libitum the 70% concentrate diet in confinement. Phase 1 ADG ranked (P < 0.05) Barn > PS > C (154, 95, and 47 g/d, respectively; SE 10.7). ADG in Phase 2 (70, 55, and 57 g/d; SE 9.3), Phase 3 (77, 82, and 72 g/d; SE 8.5), and the whole trial (94, 78, and 62 g/d for Barn, PS, and C, respectively; SE 8.2) were similar among treatments (P > 0.05). In conclusion, PEG may have potential to improve ADG by goat kids grazing tannin-containing sericea lespedeza, although testing over a longer period of time is needed. Differences in ADG in the early portion of the grazing period did not affect ADG later when a concentrate-based diet was fed, relative to continuous consumption of the concentrate-based diet.
Key words: sericea lespedeza, goats, daily gain, polyethylene glycol, tannins
Use of DNA Markers to Determine Paternity in a Multiple-Sire Mating Flock
This study was conducted to evaluate the feasibility of determining sires of progeny using DNA markers in a group-mating Rambouillet flock. Four Rambouillet rams were used in the matings. Blood was collected on rams, ewes, and lambs and DNA marker genotypes were determined using three DNA microsatellite markers. Sire assignments were made based on the genotype results. Sires were assigned to 92% of the lambs using these three markers. Mismothering was evident in 10% of the lambs because the markers indicated that the apparent dam was not the actual dam. Without knowledge of the dam’s marker genotype, sires would have been assigned to only 73% of the lambs. Using DNA analysis to determine paternity in a group mating flock is technically feasible. The number of markers required to assign paternity depends on variability among the sires for the chosen markers.
Key words: Sheep, DNA, microsatellites, paternity
Use of the Lamb Vision System to Predict Carcass Value
The need for a value-based marketing system in the U. S. lamb industry has been recognized. This study was conducted to evaluate use of the Lamb Vision System, a video imaging device, to predict lamb carcass value. Data from lamb carcasses (N = 246) that were fabricated into primal/sub-primal cuts served as the test population data set, from which value-prediction methods were developed. In addition, an additional data set of 642 carcasses, provided by Research Management Systems, Inc. (RMS), Fort Collins, CO was utilized to validate the value-prediction methods developed. Values predicted using data from the Lamb Vision System were able to account for 50-54% of the observed variability in boxed carcass value, with more accuracy compared to the traditional, hot carcass weight-based value assessment method which accounted for 25-33% of the variation in boxed carcass value. The Lamb Vision System presents the U. S. sheep industry with the opportunity to more accurately assess individual lamb carcass value.
Key words: Lamb, Carcass Value, Value-Based Pricing
Potential Associative Effects of Increasing Dietary Forage in Limit-fed Ewes Fed a 6% Fat Diet
The objective of this study was to determine how site and extent of nutrient digestion are affected by dietary forage level in ewes when the diet contains 6% crude fat by soybean oil supplementation. Five mature ewes (66.5 ? 12.8 kg of initial BW) fitted with ruminal and duodenal cannulas were used in a 5 x 5 Latin square experiment. Diets (13.9% CP, DM basis) were fed at 1.3% of BW and included bromegrass hay, cracked corn, corn gluten meal, urea, and limestone. Dietary fat was adjusted to 6% (DM basis) with soybean oil and included one of five dietary forage levels (18.4%, 32.2%, 45.8%, 59.4%, and 72.9%). Chromic oxide was used as a digesta flow marker. Ruminal pH increased (linear, P< 0.001) from 5.7 to 6.5 and VFA concentration decreased (linear, P < 0.001) with increased dietary forage. Ruminal, post-ruminal, and total tract OM digestibility decreased (linear, P < 0.06) with increased dietary forage. Ruminal starch digestibility was unaffected (P = 0.76) by treatment. Post-ruminal and total tract starch digestibility decreased (linear, P
< 0.001) with increased dietary forage. Ruminal NDF digestibility increased (linear, P < 0.05) as dietary forage increased, but post-ruminal and total tract NDF digestibilities did not differ (P > 0.23). True ruminal N digestibility was not affect ed (P = 0.29) by dietary forage level. In contrast, microbial efficiency increased from 34.3 to 47.3 g microbial N/kg of OM truly digested as dietary forage increased from 18.4 to 45.8% , then decreased to 37.1 g microbial N/kg of OM truly digest ed on the highest forage diet (quadratic, P < 0.001). Total tract N digestibility decreased (linear, P < 0.05) with increased dietary forage. We conclude that the general pattern of nutrient digestion reflects the quality of dietary ingredients when mature ewes are restricted-fed a 6% fat diet ranging from 18.4% to 72.9% forage. Total tract OM digestibility was greater than anticipated for the 59.4 and 72.9% forage diets, suggesting that positive associate effects are possible with high-forage diets containing 6% dietary fat.
Key words: Sheep, Ruminal digestion, Dietary fat
Quebracho Tannin Influence on Nitrogen Balance in Small Ruminants and In-Vitro Parameters when Utilizing Alfalfa Forage
Feeding studies using small ruminants and laboratory experiments were conducted to evaluate the level of quebracho tannin (QT) supplementation to alfalfa hay diets on plant protein nitrogen (N) use, organic matter (OM) and fiber disappearance, and in vitro ammonia production. In two separate feeding trials, sheep [Experiment 1; 12 crossbred wether lambs (avg wt 47.7 kg)] or goats [Experiment 2; 12 crossbred Boer wether kids (avg wt 32.7 kg)] were randomly assigned to one of four dietary treatments replicated three times. Lambs or kids were offered chopped alfalfa (Medicago sativa L.) hay supplemented with QT at 0.0, 0.75, 1.5, or 3.0% of the total dry matter (DM) intake. Sheep and goat diets containing 1.5 and 3.0% QT had higher (P < 0.05) fecal N excretion (g/d) than animals offered the 0.0 and 0.75% QT. As a result of greater fecal nitrogen loss, overall N digestibility was lower in sheep (P < 0.07) and goats (P < 0.05) offered the higher QT compared to 0.0 and 0.75% QT supplemented animals. Serum urea nitrogen was 11% lower in QT supplemented goats compared to goats offered no QT. Calculated in vivo neutral detergent fiber (NDF) digestibility was lower (P < 0.10) in lambs offered 1.5 and 3.0% QT diets when contrasted with lambs offered 0.0 and 0.75% QT. In laboratory studies using alfalfa hay incubated with QT, lag time for in vitro organic matter disappearance (IVOMD) was greatest (P < 0.05) for 3.0% QT when contrasted with 0.0, 0.75, and 1.5% QT, and at 48 h, IVOMD decreased quadratically(P < 0.05) with QT addition. At 96 h, %NDF remaining decreased qua-dratically (P < 0.07) with QT additions. In vitro ammonia concentrations at 6 and 12 h were lower (P < 0.05) in tubes containing 1.5 and 3.0% QT when contrasted with tubes containing 0.0 and 0.75% QT. Further investigation is needed to define QT concentrations that allow optimal N and fiber utilization when ruminants are offered high protein, low energy diets or when grazing high quality pastures.
Key words: lamb, goat, quebracho tannin, nitrogen-use
An Investigation into the Risk Factors Associated with Clinical Mastitis in Colorado Sheep
A questionnaire was designed to assess the prevalence of mastitis and associated risk factors for Colorado sheep operations during the 1999 lambing season and was mailed to 829 producers in January 2000. Responses were received from 188 producers and the data from these questionnaires was analyzed using EpiInfo Version 6.04b. Prevalence was defined as the total number of reported mastitis cases in a given flock during the 1999 lambing season divided by the total number of ewes in that flock. The mean prevalence of mastitis among sheep from Colorado owners that responded was found to be approximately 6%. Of the 188 producers that responded, 80.3% represented farm flocks, 11.2% were herded range flocks, and 8.5% were fenced range flocks. The majority of producers (84%) lambed in sheltered pens, and of those producers, 83% used small pens which housed anywhere between 5 and 20 head. Producers reported that mastitis was most likely to occur in lambing sheds (40%), in a band (23%) and in small mixing pens (22%). Sixty-eight percent of the reported mastitis cases occurred in ewes three years of age or older with the highest prevalence of mastitis (35%) occurring in ewes that were five to six years of age. Trends were observed but the only statistically significant factors (P < 0.05) found in this study were lambing in April and the Corriedale breed. Confounding factors, including pre-ventative husbandry and management procedures, may account for these results.
Key words: Sheep, Mastitis, Udder Health, Risk Factors, Prevention Strategies
Weight Changes in Fall and Spring Lambing Ewes Grazing Fallow Wheat Fields During the Summer
A total of 2714 fall and spring lambing ewes ranging in ages from 1 to 6 years were used over a three-year period to determine body weight changes during the summer grazing period (June, July and August). Ewes grazed either fallow winter wheat fields at an average stocking rate of 13.3 ewes/ha or Bermudagrass (Cynodon dacty-lon) pastures at a stocking rate of 2.5 ewe/ha. Fallow winter wheat fields were grazed for an average of 56.7 d and provided an average of 654 grazing d/ha over the three-month summer fallow period. Ewes grazing Bermudagrass pastures gained more (P = .02) weight over the summer than ewes grazing fallow wheat fields, but the amount gained by either group was greater than needed for ewes in the first 15 weeks of pregnancy or for ewes that were non-pregnant and not lactating. The standing forage available for grazing in fallow winter wheat fields consisted of broadleaf weeds, warm and cool season grasses, and wheat straw. It appeared that weight gains were greater when more of the standing forage was in the form of grasses than as wheat straw. Using ewes for biological control of accumulation of above ground biomass during the summer fallow period did not consistently result in lower fall forage and spring wheat grain production as compared to using herbicides to fallow the fields. Fallow winter wheat fields can be used during the summer to provide standing forage that is high enough in nutrient density to support pregnant and open ewes, but not without decreasing subsequent production of forage or grain.
Key words: Sheep, Biological control, Summer fallow, Wheat, Weight gains.
Effect of Ethanol Supplementation on In Vitro Digestion and VFA Production and Growth Performance of Newly Weaned
The objectives of these studies were to determine the effects of ethanol (ETOH) supplementation on DM digestibility and VFA production in an in vitro system and on growth performance of newly weaned lambs. For Exp. 1, four ruminally cannu-lated beef heifers were used as ruminal fluid donors for an in vitro trial. Two of these heifers received a commercial rice hulls-based supplement containing ETOH (Corner Post, Free Choice Enterprises, Richland, Iowa) for 14 d before ruminal fluid collection (adapted), whereas the other two heifers received no supplement (unadapted). Substrates included 0.5 g oat hay (OH) or 0.44 g oat hay plus 0.06 g ETOH supplement (ES). Data were analyzed as a split-plot with adaptation to ETOH supplement as the main-plot and type of substrate as the sub-plot factor. At 6 h of incubation, in vitro dry matter disappearance (IVDMD) tended to be greater (P = 0.09) for adapted than unadapted ruminal fluid, and OH had greater (P > 0.02) IVDMD, total VFA concentrations, and molar proportions of acetate, butyrate, iso-valerate, and valerate than ES. Adaptation to ETOH supplement improved (P = 0.03) 48-h IVDMD of OH and ES. At 12 h, ruminal fluid adapted to ETOH supplement increased (P = 0.03) total VFA from OH substrate. By 24 h of incubation, adaptation or dietary substrate effects on total VFA and molar proportions of individual VFA were not significant (P < 0.60). For Exp. 2, 24 Rambouillet crossbred lambs (25.0 ? 0.4 kg) were blocked by body weight and allotted to one of 12 pens resulting in two lambs per pen with four replications per treatment. Lambs were fed no supplement (CON), the commercial ETOH supplement (ES), and the ETOH supplement dried (DRY) to evaluate the commercial supplement without the ETOH. Experimental treatment differences were evaluated using orthogonal contrast comparing CON vs. supplement and ES vs. DRY. Overall (d-0 to d-42) DMI and ADG were not different for CON vs supplement (P = 0.71 and 0.63, respectively) or ES vs DRY (P = 0.83 and 0.41, respectively). We conclude that adaptation of ruminal microflora to ETOH supplementation will improve diet digestibility, but the improvement in diet digestibility is not sufficient to enhance growth performance of newly weaned lambs.
Key Words : Lambs, Ethanol, Supplementation, Digestion, Growth
Growth and Reproductive Performance of Ewe Lambs Implanted with Zeranol after Weaning, but before Sexual Maturation
Reproductive and growth performance was evaluated in weaned ewe lambs implanted with zeranol (12 mg, Ralgro, Shering Canada, Inc.) at weaning. In Exp. 1, white-faced ewe lambs (BW = 29.5 ? 0.1 kg) were stratified by body weight and randomly allotted to control (n = 30) or implanted (n = 30) groups. Lambs were fed to achieve gains of 0.23 kg/hd/d for an 84 d period. Five non-pregnant animals from each group were slaughtered during the ane-strous season and reproductive tract and ovarian weights were obtained. In Exp. 2, implanted (n = 10) and control (n = 10) ewe lambs (BW = 36.9 ? 0.4 kg) were individually fed a complete ration formulated to achieve gains of 0.23 kg/d for a 63 d period. Ewes were exposed to fertile rams during the breeding season in Exp. 1 and Exp. 2 and pregnancy rates were determined by ultrasound. In Exp. 1, ewes with zeranol implants had greater (P=0.01) gain efficiency and gained more (P=0.02) weight by 42 d than control ewes. Implanted ewes ended the 84 d growth study heavier (P=0.01) than control ewes. Differences were not noted in days to first estrus (P=0.58) or overall pregnancy rates (P=0.29; 43.3% and 30.0% for control and implanted ewes, respectively). However, ovarian weights (P=0.06), but not total reproductive tract weights (P=0.47), tended to be lighter in implanted than control ewes. In Exp. 2, ewes with zeranol implants were numerically heavier by the end of the 63 d growth study than control ewes, however, differences did not reach statistical significance (P=0.31). Differences in gain (P=0.46) or gain efficiency (P=0.48) were not noted in Exp. 2. As in Exp. 1, overall pregnancy rates did not differ (P=0.37) between control (60%) and zeranol (40%) treated ewes. Implanting weaned ewe lambs with zeranol may enhance growth performance and gain efficiency without affecting reproductive performance. However, numbers in the present study were limited and the numerical trends for decreased reproductive performance of implanted ewe lambs may need to be considered if a large proportion of the ewe lambs will be kept as replacement females.
Key words: Zeranol, Ewe Lambs, Growth, Reproduction
Consumer Evaluation of Pre-Cooked Lamb
A cook-in-bag lamb in curry sauce product was evaluated by 166 consumers in three separate experiments. When the product was identified as lamb it received favorable evaluations for taste and tenderness. In blind testing a majority of participants were unable to distinguish the lamb product from a similarly prepared beef product. The hypothesis that the lamb and beef products were equally likely to be preferred could not be rejected.
Key words: Consumer evaluation, lamb shoulder, value-added
Caprine Arthritis-Encephalitis: An Update
Caprine arthritis encephalitis (CAE) is a disease most commonly recognized in adult goats and manifested clinically as chronic degenerative polyarthritis, interstitial mastitis, and/or pneumonia. Occasionally, CAE may be characterized by acute leukoen-cephalomyelitis, particularly in 2 to 6 month-old kids. The disease is caused by caprine arthritis-encephalitis virus (CAEV), a lentivirus closely related to other human and animal lentiviruses, particularly ovine lentivirus (OvLV).
In the majority of industrialized countries, CAE is considered one of the most devastating diseases of dairy goats. In the United States of America, the prevalence of serum antibodies against CAEV in dairy goat herds ranges from 38 to 81%. The negative impact of this infection is associated to direct production loses as a result of clinical disease and related secondary infections, to animal deaths, and indirectly due to trading restrictions that some countries impose on infected herds.
The main route of transmission is through milk and colostrum from infected nannies to their offspring. Currently, there are no commercial treatments or vaccines available to control or prevent CAE. As a result, identification of CAEV-infected goats by serological means and elimination of positive reactors is a practice often used to achieve CAE-free status in herds. The separation of offspring from their mothers before ingestion of colostrum and their feeding with heat-inactivated colostrum and milk replacers is used for control purposes as well. However, this method is labor intensive and not always effective.
As a result of recent advances in genetic engineering and molecular virology, new approaches for the control of infectious diseases of livestock are being developed. These new technologies are likely to provide the means for more effective ways to control and eradicate CAE and other infectious diseases of livestock.
An Evaluation of Different Energy Supplements for Lambs Consuming Endophyte-free Tall Fescue
Twenty-five, growing, Dorset and Dorset cross wether lambs (avg BW of 32.8 kg) were used in a completely random design to evaluate the effect of source of supplemental energy on total tract digestibility, N balance, and serum metabolites. Following an initial 10-d adaptation to fresh-chopped, boot stage tall fescue, another 14-d adaptation period was used to allow lambs to acclimate to one of five experimental treatments. A 7-d total fecal and urine collection followed, and approximately 7 mL of whole blood was collected via venipuncture of the jugular vein on d 7 of the collection period. Treatments included: 1) fresh-cut forage only (CON); 2) CON plus dried molasses (MOL); 3) CON plus dried beet pulp (BEP); 4) CON plus soybean hulls (HUL); and 5) CON plus ground corn (GRC). Supplements were formulated to provide 27.1 g of ruminally degradable nitrogen (RDN)/kg of ruminally digestible OM (RDOM). Isolated soy protein was used to increase the RDN of the BEP, MOL, and GRC diets so that all supplements were isonitrogenous (avg N intake = 13.4 g/d). Total tract DM digestibility was greater (P < 0.05) for BEP, HUL, and GRC compared to MOL and CON. Nitrogen balance did not differ (P = 0.15) among treatments; however, urinary N excretion tended (P < 0.08) to be greater for unsup-plemented lambs when compared to BEP, HUL, and GRC with MOL being intermediate. Additionally, serum urea nitrogen (SUN) concentrations were less (P < 0.05) for all supplemented wethers. Serum glucose concentrations did not differ (P = 0.40) across treatments. Greater SUN concentrations for lambs fed fresh-chopped tall fescue resulted in slightly greater urinary N excretion, suggesting that N utilization was better for supplemented lambs. Balancing RDN:RDOM with supplemental dried beet pulp, soybean hulls, or ground corn may be a management strategy to reduce N excretion by lambs consuming tall fescue pastures.
Key words: Lambs, Supplementation, Serum metabolites, Nitrogen balance
Effects of the FecB Gene in Half-sib Families of Rambouillet-cross Ewes
Records of Booroola-Rambouillet ewes (N = 94) were analyzed to estimate the difference between carriers (B+) and non-carriers of the FecB gene for ovulation rate, fertility, litter size, number of lambs weaned, fleece weight, and body weight within paternal half-sib families. The ewes were progeny of heterozygous (B+) Booroola-Rambouillet rams (n=5) mated to homozygous (++) Rambouillet ewes. Genotype at the FecB locus was predicted using DNA markers known to be linked to the FecB locus. The estimated differences between B+ and ++ ewes were +1.18 ? .12 ova/cycle (P=.0001) for ovulation rate, +.51 ? .16 lambs born/ewe lambing (P=.002), and +.18 ? .18 lambs weaned/ewe lambing (P=.34) in first-parity ewes. Estimated body weight differences between B+ and ++ ewes were -.88 ? .97 kg at 7 mo of age (P = .36) and -2.10 ? 1.15 kg at 18 mo of age (P = .07). Greasy fleece weights at 15 mo of age were not different between predicted FecB genotypes (P = .48). Assignment of genotype based on linked DNA markers effectively identified ewes that are heterozygous carriers and those that are non-carriers for FecB. Ewes predicted to be B+ had significantly greater ovulation rate and litter size compared to their ++ half-sibs. The difference between B+ and ++ ewes was generally not significant (P> .05) for other traits.
Key words: Sheep, Rambouillet, Booroola Merino, Reproduction, Marker assisted selection
The Effects of Energy Source and Ionophore Supplementation on Lamb Growth, Carcass Characteristics and Tenderness
Commercial Hampshire x Dorset crossbred lambs (n = 96) were used in a 3 x 2 factorial experiment to determine the effects of energy source (high concentrate (HC), high forage (HF), a combination of concentrate and forage (MIX)); and ionophore supplementation (monensin; Rumensin [Elanco Animal Health, Greenfield, IN] fed at a rate of 176 mg per kg of feed) on lamb growth and carcass characteristics. The wethers (n = 48) were harvested and the effects of energy source and ionophore supplementation on carcass characteristics and palatability attributes were evaluated.
Energy source affected (P < .05) dry matter intake, average daily gain (ADG), feed efficiency (FE), and days on feed. Lambs fed the HF diet had the lowest (P < .05) ADG (204 g), the least (P < .05) desirable FE (0.139 g/f), and consequently the most (P < .05) days on feed (106 d). Carcasses from lambs fed the HF diet also had less (P < .05) bodywall thickness, less kidney and pelvic fat, a smaller ribeye area, and lighter liver weights. Longissimus dorsi samples from the lambs on the HC diet had significantly (P < .05) higher Warner-Bratzler shear force values than the lambs on the HF and MIX diets. The sensory panel found longissimus dorsi samples from lambs that received the MIX diet significantly (P < .05) more tender when compare to those from lambs that received the HC and HF diets.
Monensin decreased (P < .05) backfat by 1.22 mm (20%) and dressing percentage by 3.1%. Monensin had no adverse effects (P > .05) on sensory attributes. Therefore, feeding monensin to lambs fed various diets resulted in no adverse carcass characteristics and a slight decrease in back fat depth.
Key words: Ionophore, Lamb, Growth, Carcass, Tenderness
Effects of Supplementing Ewes with d-a-Tocopherolon Serum and Colostrum Immunoglobulin G Titers and Preweaning Lamb Performance
Two experiments were conducted to examine effects of d-?-tocopherol (vitamin E) on colostrum immunoglobulin G (IgG) titers and preweaning lamb performance. Trial 1 consisted of 86 Suffolk ewes receiving either no vitamin E (control) or 1500 IU vitamin E on d-28 prepartum. From the 86 ewes, a subset of 25 ewes was randomly chosen for an intensive analysis of ewe serum and colostrum IgG and lamb serum IgG concentrations. Average daily gain was analyzed for lambs (n = 100) born to the 86 ewes as well as for lambs (n = 25) born to the subset of 25 ewes. Birth weights were also analyzed for the 25 lambs. Vitamin E supplementation had no effect on ewe serum (P = .16), lamb serum (P = .77) or ewe colostrum (P = .25) IgG concentrations. Of the intensively sampled lambs, those born to vitamin E-treated ewes had heavier (P = .08) birth weights and greater (P = .02) ADG than lambs born to control ewes. Average daily gain for lambs born to the 86 ewes was not affected by vitamin E (P = .97; n = 100). Trial 2 examined effects of vitamin E on lamb growth under range conditions. Two hundred whiteface, pregnant ewes were randomly sorted into four pastures with two pastures per treatment. Ewes received either no vitamin E (control) or 1500 IU vitamin E 40 d before the onset of lambing. Lambs from vitamin E-treated ewes showed higher weight gains at 30 d of age than lambs from control ewes (P = .03). However, weaning weights were similar (P > 0.10) for both treatment groups. Vitamin E does not appear to increase IgG concentrations in ewe and lamb serum or ewe colostrum. However, vitamin E showed positive effects on growth when lambs were under stress conditions during the first several weeks postpartum as indicated by intensively sampled lambs in Trial 1.
Comparing Indicators of Sheep Grazing Leafy Spurge and Perennial Grasses
Sheep and goats are increasingly being used to control the invasive leafy spurge (Euphorbia esula L.). Our objective was to compare three indicators of sheep use of leafy spurge and two native bunchgrasses, Idaho fescue (Festuca idahoensis Elmer) and bluebunch wheatgrass (Pseudoroegneria spi-cata [Scribn. and Smith] A. Love) on an upland site in southwestern Montana. We used yearling Targhee ewes in a 3 year study (1992-1994). One group of ewes (naive) had no previous exposure to leafy spurge whereas the second group (experienced) had been pastured on a leafy spurge-infested (25-50% cover) foothill rangeland as lambs. Sheep were rotated through 3 paddocks for 9 grazing periods in 1992 and 7 grazing periods in 1993 and 1994. Grazed plant frequency (%) and canopy removed (%) were estimated after sheep were removed from each paddock. Time spent grazing (%) on the different species was estimated for one week periods in early, mid-, and late summer 1992 and 1993, and at five day intervals for the first 35 days in the 1994 grazing season. Overall, the 3 measures of use indicated leafy spurge was less likely to be grazed than the two native grasses in early summer, but more likely to be grazed in mid-and late summer. In general, the sheep removed more of the canopy of leafy spurge than of grasses. During the early summer grazing period, all 3 measures of use indicated experienced sheep were more likely to graze leafy spurge than naive sheep. As expected, grazed plant frequencies were often high because any evidence of grazing was noted, whereas canopy removed more closely reflects ecological impacts of grazing. The behavioral time spent grazing results usually concurred with grazed plant frequency and canopy removed measured after sheep were removed from a given paddock.
Key words: weed, Euphorbia esula, grazing, nutritive value
Research Note – Repeated Injections of Pregnant Mare Serum Gonadotrophin (PMSG) Failed to Induce Antibody Production in Fall Lambing Ewes
Pregnant Mare Serum Gonadotrophin (PMSG) is commonly used to induce estrus/puberty or superovulate beef cows (Gonzalez et al., 1994), dairy cows (Kummer et al., 1980; Saumande et al., 1984), gilts or sows (Holtz and Schlieper, 1991) or ewes (Evans and Robinson, 1980; Jabbour and Evans, 1990). Across species, variation in the success of recovering viable ova or embryos following PMSG can be attributed to hormonal profiles postinjec-tion (Bevers and Dieleman, 1987), age of treated animal (Lerner et al., 1986) or day of the cycle on which treatment is administered (Moor et al., 1984). Reduction in time of activity of PMSG has been attempted by administering PMSG antibodies, but success has been variable (Kummer et al., 1980; Jabbor and Evans, 1990; Kirkwood etal., 1994). Another factor that diminishes the effectiveness of inducing ovulation is the number of superovulatory treatments to which an animal has been subjected (Christie et al., 1979; Moor et al., 1984). The objective of this study was to examine whether conception rate of ewes induced to ovulate out of season in successive years could be attributed to presence of circulating antibodies to PMSG.
Case Report – Monensin Poisoning in a Sheep Flock
An outbreak of monensin poisoning caused severe muscular dysfunction in sheep. Fifty-eight sheep from a flock of approximately 180 died. Affected animals had dark urine, stiff gait and/or intermittent recumbency. At necropsy, animals which died acutely had pale tan striations spread throughout the cardiac muscle. Similar, but less severe changes were seen in skeletal muscles including the diaphragm. In a lamb that survived longer, the myocardium and skeletal muscles presented larger, coales-cent, pale irregular areas. Histologically, muscle fibers were swollen and fragmented or had hyalinosis and loss of striation. Prominent satellite cell proliferation and mononuclear cell infiltration were evident in the muscles of chronically affected lambs. Toxicologic analysis revealed that the ration contained 334 ppm of monensin. In sheep, monensin toxicity occurs sporadically due to accidental or extra-label use. Differential diagnoses for cases of monensin toxicosis in sheep should include vitamin E and selenium deficiency, poisoning by myotoxic plants, and gossypol toxicity.
Volume 17, No. 3
Sheep & Goat Research Journal. Volume 17, No. 3: 2002 — Special Issue: Breeding for Meat Production
Preface and Overview
On a world basis, sheep are kept for a variety of reasons, but in this country the primary uses have been meat and fiber production. At present there is also a limited and growing interest in milk production from sheep. One of the more recent and growing roles for sheep is that of vegetation management, including optimum grazing and range management practices (Havstad, 1994), control or assisting in the control of noxious vegetation (Olson and Lacey, 1994), reduction of fuel loads for fire control or retardation (Taylor, 1994), and reducing vegetative competition in reforestation efforts (Sharrow, 1994). Even flocks used for vegetative management must produce a marketable commodity to justify their costs or to provide an outlet for surplus animals. Because a majority of the world?s sheep are wool producers (at some level) it seems likely that in earlier periods fiber production was viewed as their more important contribution. Historically wool was an important item in world trade, but this special place is declining.
Selection for Reproductive Efficiency
Number of lambs weaned per breeding ewe has a greater influence on productivity of the sheep enterprise than any other trait. Net reproductive rate is determined by several components, with fertility, prolificacy (litter size) and lamb livability having the greatest influence (Wang and Dickerson, 1991). Age at puberty, prenatal viability and, in some enterprises, out-of-season fertility, can also contribute.
Genetic and Environmental Impacts on Prenatal Lamb Loss
Four ‘facts’ apply to most commercial sheep flocks:
- Number of lambs sold has a greater influence on flock income than any other factor under the producer’s control.
- Ewes producing single lambs are moneylosers!
- Producers put in great effort at lambing to maximize lamb survival and then fight predators to keep lambs alive until marketing.
- MANY SHEEP FLOCKS LOSE MORE LAMBS BEFORE LAMBING THAN AFTER.
The average flock loses about 15% of lambs from birth to weaning. Numerous studies have shown that the embryonic loss rate in the first 30 days after mating often exceeds 20%. These are potential lambs which the producer never knew existed; however, they are just as surely lambs not marketed as are lambs eaten by coyotes, although lambs that die after birth will usually represent greater investment of feed and labor than those lost prenatally.
To the producer, the most important prenatal losses occur in ewes that ovulate two eggs but give birth to only one lamb. The ewe’s costs for maintenance, labor, and depreciation are unchanged and usually more than the sale value of her resulting single lamb. Research results indicate that the percentage of twin-ovulators that lose one embryo ranges from about 10% to over 40%.
This paper will look at loss of potential lambs before lambing and some of the factors affecting loss rates.
It has been established that net reproductive rate (lamb crops weaned) is the largest contributing factor to efficiency of lamb meat production (Large, 1970). With the present low rate of return from wool production, it is imperative that producers who will survive must produce meat more efficiently. There is also a need to increase overall numbers of lambs produced in order to justify the maintenance of the necessary infrastructure to sustain the industry. On a flock basis there are a number of components of net reproductive efficiency including age at sexual maturity, length of productive life, seasonality of reproduction, frequency of lambing, ewe fertility, ovula-tion rate, embryo mortality and lamb survival. Among these, it has been suggested that under some conditions, reducing lamb mortality offers the greatest opportunity to improve the efficiency of the flock (Wang and Dickerson, 1991).
Opportunities to Reduce Seasonality of Breeding in Sheep by Selection
Seasonal reproduction is a serious problem for the sheep industry, reducing effectiveness of accelerated lambing programs, restricting flexibility to integrate lambing into other farm activities, and limiting access to favorable seasonal markets. Environmental or hormonal stimulation of reproduction requires increased investment in feed, labor, and (or) facilities, increases cost of production, often requires access to products that are not readily available or not approved for use in sheep, and may not be feasible in extensive or semi-extensive production systems. However, less intensive and less costly management interventions are available to improve reproduction; chief among these is use of the ram effect (Oldham and Fisher, 1992). In addition, substantial evidence exists to document genetic differences in seasonality of breeding, leading to opportunities to reduce seasonality by selection.
This review will address potential for genetic improvement of reproduction in sheep in both annual autumn and accelerated lambing systems. Satisfactory reproductive performance in both systems is mainly limited by the need to lengthen the breeding season to encompass spring and summer matings. In annual lambing, a shift in the annual pattern of reproductive behavior may be sufficient to meet the needs of the program, and ram effect is a useful tool for induction of estrus. In contrast, accelerated lambing systems place a premium on rapid rebreed-ing which is not required in annual lambing. Accelerated systems thus generally require more careful timing of ram effect and greater genetic sensitivity of ewes to ram introduction.
Selection to reduce seasonality of breeding involves application of the principles well-established. Selection among existing breeds is used to establish a flock with desirable initial characteristics. A breeding program is then designed to appropriately utilize complementary breed effects and hybrid vigor. And finally, selection within the flock is implemented to generate genetic improvement in economically important traits.
Strategies for Genetic Improvement of Carcass Value in Lambs
Improving carcass composition is one factor that can have an impact on lamb consumption and demand (Ward, 1995; Purcell, 1998). Increased size of cuts and decreased fatness are two factors that affect consumer acceptability of lamb (Jeremiah et al., 1993). The lamb producer that markets superior carcasses, with greater consumer appeal, expects to realize financial rewards from doing so. The expectation of greater income received from marketing superior lambs is motivation for producers to develop a strategy to improve carcass value through selection of genetically superior breeding stock. Using genetic selection to change traits measured on carcasses is different from many traits that can be measured on live animals because direct measurements are not available on the animals to be used for breeding stock. However, progress from selection on correlated traits can yield substantial changes over time.
The importance of increasing our knowledge of lamb carcass composition has been recognized for years. There were several publications from US scientists in the 1960?s that addressed prediction of lamb carcass composition, (Field et al., 1963; Judge et al., 1966; Spurlock & Bradford, 1965) lamb carcass value, (Carpenter et al., 1964; Carpenter et al., 1969; Cunningham et al., 1967) and genetic selection for improvements in carcass traits (Botkin, et al., 1969; Bradford, 1967). These US publications were preceded by earlier work of scientists in New Zealand (Barton and Kirton, 1958; Kirton and Barton, 1962; Kirton et al., 1962) and the UK (Bichard and Yalcin, 1964; Bowman et al., 1968). The 57th Annual Meeting of the American Society of Animal Science, held in 1965, included an invited presentation by Dr. G. E. Bradford (1967) titled: “Genetic and economic aspects of selecting for lamb carcass quality”. The working definition of quality in this paper was “percent of lean meat, especially in the preferred cuts, and having desirable eating quality.” One of Dr. Bradford’s conclusions was “… significant genetic improvement in lamb carcass quality will depend upon the development of reasonably accurate live animal measures of carcass quality.”
Considerable developments have occurred in the technology available to measure body composition in live animals. However, the change in carcass composition of US lambs has been limited. Although the technology to measure body composition is available, the financial incentive to make genetic improvement in body composition has not been large enough to encourage breeders to place much emphasis on carcass traits. Therefore, the issue of genetic improvement of carcass composition involves not only genetics and measurement of body composition, but also economics. Nsoso et al. (1999) reviewed several aspects of selection for growth and carcass composition. The purpose of this paper is to review issues relevant to developing a strategy for US lamb producers to select for improved carcass value in lambs.
Relationships Among Traits: Growth Rate, Mature Size, Carcass Composition and Reproduction
Genetic variation in any one trait is often associated with variation in other traits. Thus successful selection for one performance trait may impact other traits affecting efficiency of production. The correlated changes may be favorable or unfavorable, depending on the nature of the genetic relationships among the traits and the contribution of each to production efficiency.
Composite Trait Selection for Improving Lamb Production
When the value of wool is low, as at present, there is a greater potential for increasing both biological and economic efficiency of sheep production through improvement in meat production. It has been suggested that biological and economic efficiency can be increased more through genetic selection for improved reproductive rate than in growth rate or body composition (Fogarty et al., 1982). Reproductive rate is the most important component of total litter weight, which is clearly the single most important economic trait in American commercial sheep production. Loss of the Wool Incentive Program and lower wool prices in recent years have increased the economic importance of the total litter weight weaned per ewe. Current farm prices for wool and lamb indicate gross income from lamb exceeds that from wool by up to sixteen fold for most commercial producers of western white faced sheep. Hence, genetically increasing marketable litter weight per ewe is one of the most important contributions genetics can make to the economy of the sheep industry.
Increases in litter weight weaned can be made quickly through crossbreeding especially with prolific breeds. However, introduction of new breeds, often exotic, can result in unadapted genotypes with or without other desirable characteristics. Also, after crossbreeding has been thoroughly exploited, the only recourse for continued genetic progress is via selection for genetically superior individuals within breeds or crosses. It is important, therefore, to determine the relative effectiveness of alternative selection procedures for improving litter weight weaned.
The trait, litter weight weaned, is a composite trait affected by the expression of several genetically influenced traits. Variation in these component traits contributes to the phenotypic variation in the composite trait. Litter weight weaned is a combination of several different aspects of ewe reproduction (fertility, and litter size), ewe viability and offspring growth rate (mothering ability, milking performance, lamb survival, lamb growth rate). Thus, it is a convenient biological and economic measure of ewe productivity (Martin and Smith, 1980; Ercanbrack and Knight, 1985).
Long term selection for a composite trait may (but not necessarily) improve each individual component trait. Component traits within a composite trait should not be expected to improve at the same rate because they may differ in the genetic parameters involved. However, selecting for a composite trait should result in a balance among the component traits that produces an adapted animal, while selection for an individual trait can result in a reduction in adaptability. For example, selection response for a non-composite trait such as ovulation rate in sheep may be positive but gains in ovulation rate can be offset by decreased embryo survival (Bradford, 1985). Similarly, selection for increased litter size at birth may not be accompanied by increased milking performance and lamb growth rate. There may be limiting factors associated with favorable major genes such as the Booroola (FecB) allele which increases ovine ovulation rate substantially. While the FecB allele will increase litter size, there are associated decreases in lamb survival and weaning weight (Willingham and Waldron, 2000).
Direct selection for the composite trait of litter weight weaned in mice was three times as effective as selection for litter size for increasing litter weight weaned (Luxford and Beilharz, 1990). Long term selection in Targhee sheep for individual lamb weaning weight, rather than total litter weight weaned, resulted in decreases in lamb survival to weaning and ewe fertility (Bradford et al. 1999). From this last study, it is obvious that single trait selection for growth rate to weaning can improve weaning weight but it does not necessarily increase total lamb production per ewe. Thus, litter weight weaned per ewe exposed is the most appropriate composite trait to be used in selection for increasing total lamb production. The objective of this review is to characterize the composite trait litter weight weaned and its component traits.
Fundamental Aspects of Crossbreeding of Sheep: Use of Breed Diversity to Improve Efficiency of Meat Production
The sheep industry competes against beef, pork, poultry, and fish for food dollars of consumers who have many choices of high-quality meats. To compete effectively, the industry needs to produce uniform, nutritious, lean lamb that satisfies the eating preferences of consumers and to improve reproductive efficiency and reduce labor requirements so that seedstock and commercial flocks are both practical and profitable under a range of production environments. Although this situation indeed represents a difficult challenge, sheep producers have an invaluable resource to make necessary changes – a wealth of biodiversity represented by numerous breeds. Breeds of sheep have evolved over many thousands of years, their utility and function guided by their ability to adapt and survive in specific environments and production systems. Following domestication, further diversification among breeds has stemmed from selection by man for numerous characteristics, for example, appearance, color, size, shape, or wool production. Consequently, breeds of sheep differ markedly in adaptability to different environments and in levels of performance for traits that influence efficiency of production and product quality. Characteristics of each breed have a genetic basis and can therefore be exploited in structured crossbreeding systems designed for specific production-marketing situations. The purpose of this manuscript is to provide guidelines to improve efficiency of meat production through the appropriate use of breeds in crossbreeding systems.
Use of Finnsheep Crosses in a Western Commercial Sheep Operation
The Hamilton family has been engaged in agriculture, including sheep production, in California for more than 130 years. The farming and ranching operation is diversified, and includes row crop farming, dry land grain and safflower farming and livestock which also includes cattle. The sheep flock today consists of about 3800 commercial whiteface ewes that are 3/8 Finn, and about 85 purebred Suffolk ewes.
The climate of the area is Mediterranean, with rain from October or November to March or April, and thus with a dry season of at least six months in most years. Sheep are an integral part of our cropping system, and particularly important to the dryland wheat and barley production, which is our largest cropping enterprise. Following harvest of the grain crop, the sheep graze the crop residues during the summer. The land is left fallow the following season or sometimes two seasons, but with the rains there is a substantial “volunteer” crop of grasses and forbs, which provide good grazing for the sheep. If not grazed, this growth would make crop preparation the following season more difficult, especially in better than average rainfall years. Sheep have an advantage over cattle in this system in that they cause much less compaction of the heavy clay soils. The ranch includes considerable areas of native grass range that are also grazed much of the year to complement the stubble and fallow grazing. The sheep are also used to enhance sensitive native California grasslands for the Nature Conservancy, Solano County Open Space and the California Fish and Game Department.
Ewes are lambed in two seasons, a fall lambing from October 18 to December 15, when 75% or more of the mature ewes lamb, and a winter lambing from January 20 to March 15, when the ewe lambs and remainder of the mature ewes lamb. Ewes in each group are pregancy tested and separated by fetal count and estimated stage of gestation. Mature ewes with singles are generally field lambed, while those carrying multiples and all ewe lambs are barn lambed. A very successful fostering system is used to maximize the number of ewes raising twins and minimize the number of ewes that fail to raise a lamb.
Volume 17, No. 2
Sheep & Goat Research Journal. Volume 17, No. 2: 2002
Fall and Winter Grazing of Brassicas – a Value-Added Opportunity for Lamb Producers
Fast-growing cold-tolerant brassicas can be grown as a second crop, providing low-cost, high quality forage for fall-grazing lambs. In this study, cultural methods on irrigated fields included species and varieties, establishment method, second-crop planting dates (July 17 to August 12) and volunteer grain control. Brassicas were planted after several primary crops. Studies were conducted at the Powell, WY, Research and Extension Center from 1986 to 1996. Lamb performance was evaluated in seven grazing studies. Brassica forage production declined about 770 kg/ha per week when planted after July 20. Two to 3 metric tons/ha of forage was available in all years, except 1992, when soil fertility was low. Average daily gain (ADG) was similar for turnips and other species (tyfon, rape, radish). Over all studies, lambs grazing brassicas gained 0. 18 kg (0. 13 to 0. 25) per day. During the first month, lambs grazing turnips and other forages gained faster than drylot-fed lambs, but gained slower than drylot-fed lambs after the first month. Average lamb gain/ha was 308 kg. Gains of lambs grazing July-planted brassicas were 41% greater than with August-planted brassicas. The average number of lamb grazing days/ha was 1685. Brassica-grazed lambs gained subsequently as well in drylot as lambs not previously grazed. Carcass characteristics of lambs grazing brassicas were similar to those of lambs fattened in the drylot; however, grazed lambs required longer to reach target weights.
Key words : turnip, tyfon, rape, radish, sheep, weight gains.
Effects of Prenatal Shearing of Ewes on Birth Weight and Neonatal Survivability of Lambs
A three-year study was conducted with a flock of mixed-aged Rambouillet ewes to determine the effect of late-gestation shearing on lamb birth weights (N = 480) and survival rates during the neonatal period in typical West Texas conditions. Ewes were randomly assigned, within sire family and year of birth, to one of two shearing treatments, prenatal shorn or unshorn. The ewes remained on the same treatment for all 3 years. The prenatal shorn ewes were shorn in early January, 2 to 54 d prior to lambing (mean = 20 d). The unshorn ewes were shorn after lambs were an average of 96 d old. Lamb survival rates were analyzed using a model that included fixed effects of shearing, year, sex of lamb, type of birth, age of dam, significant interactions, and linear and quadratic effects of birth weight and ambient minimum temperature on the day of birth. Lamb survival rates were not affected by age of dam, but were lower (P < .02) on day 3 for triplet compared to twin and single lambs (74.3, 88.0 and 89.2 ? 5%, respectively). A significant interaction between sex of lamb and shear treatment (P < .05) was found for lamb survival. Male lambs from shorn ewes had 12% lower (P < .01) survival rates at one day of age than male lambs born to unshorn ewes, whereas, survival rates of female lambs was not affected by prenatal shear treatment. Lamb birth weight ranged from 1.6 to 7 kg and was not affected by shear treatment (P > .5). Lamb survival rates increased quadrat-ically as both birth weight (P < .05) increased and as minimum temperature on day of birth (P < .01) increased. Predicted lamb survival rates at 3 days of age for 3, 4, 5, and 6 kg birth weight lambs were 81.7, 91.0, 95.0 and 94.0 ? 4%, respectively. Predicted lamb survival rates at 3 days of age for minimum temperatures at lambing of-7,-1 and 4? C were 72.1, 88.8 and 93.5 ? 5%, respectively. The results of the present study demonstrate that prenatal shearing of Rambouillet ewes 20 d prior to lambing in typical West Texas conditions did not increase birth weights or improve survival rates of neonatal lambs.
Key words: birth weight, lambs, shearing, survivability
Scrapie in Sheep: A Transmissible Spongiform Encephalopathy
Scrapie is a transmissible, fatal, degenerative disorder of the central nervous system that affects sheep and goats. It belongs to a family of neurodegenerative diseases in mammals known as transmissible spongiform encephalopathies (TSEs), which includes bovine spongiform encephalopathy (BSE) in cattle, Creutzfeldt-Jakob Disease (CJD) in humans, and chronic wasting disease in deer and elk (Johnson and Gibbs, 1998). The focus of this review is on scrapie, which affects most sheep-producing countries in the world.
Effect of Colostrum Intake on Serum Hormone Concentrations and Immunoglobulin G Absorption in Neonatal Lambs
Colostrum contains nutrients, immunglob-ulins, hormones, and growth promoting substances, such as insulin-like growth factor?I (IGF-1). An experiment was conducted to study the effects of feeding three amounts of colostrum on immunoglobulin G (IgG), and hormone concentrations during the first 18 hours of life. Fifteen Rambouillet x Merino lambs were assigned to three treatments. Pooled colostrum was fed at 10 mL/kg of body weight (BW), 20 mL/kg BW, or 30 mL/kg BW every 3 hours for 15 hours. Blood samples were obtained from lambs immediately after birth and every 3 hours through hour 18. Concentrations of growth hormone (GH), prolactin (PRL), triiodothyronine (T3) and thyroxine (T4) did not differ (P > .10) among treatments. Serum IgG, IGF-1 and insulin (INS) increased linearly (P < .03) as colostrum intake increased. A quadratic effect (P = .06) was detected for concentrations of GH as colostrum amounts increased. Feeding increasing amounts of colostrum following birth influenced serum IgG, INS, IGF-1 and GH concentrations, thereby, influencing both passive immunity and endocrine status in lambs. Feeding 10 mL/kg produce no health- related mortality at either a week of age or at weaning. Ten mL/kg of BW of colostrum every 3 hours for 15 hours may provide sufficient nutrition, growth-promoting factors and IgG to lambs at high risk.
Key Words: lamb,hormone,immunoglobu-lins, colostrum
Adipose Tissue Lipogenic Enzyme Activity, Serum IGF-I, and IGF-Binding Proteins in the Callipyge Lamb
The purpose of this study was to determine if reduced adipose tissue accretion in callipyge lambs during growth was related to activities of lipogenic enzymes and serum concentrations of insulin, insulin-like growth factor-I (IGF-I), and IGF-binding proteins. Normal lambs were homozygous normal (clpg/clpg), and callipyge lambs were heterozygotes (CLPG/clpg). Lambs were slaughtered at 25, 41, 57, or 73 kg (target live weight groups), with five normal and five callipyge lambs in each weight group. Subcutaneous, intermuscular, and perirenal adipose tissue samples were dissected as soon as possible after slaughter from the 41, 57, and 73 kg groups. Tissue homogenates were prepared for assay of fatty acid synthase, acyl-CoA synthetase, glycerophosphate acyltransferase, and lipoprotein lipase activities. Most numeric values for enzyme activities were higher for the normal lambs in each adipose tissue depot. Callipyge lambs had lower (P = 0.05) glycerophosphate acyltransferase activity in subcutaneous adipose tissue at 41 kg. In intermuscular adipose tissue, each enzyme activity was lower (P < 0.05) at 41 kg for callipyge lambs. In perirenal adipose tissue, fatty acid synthase and glycerophosphate acyltransferase activities were lower (P = 0.02) for callipyge lambs at 41 kg, and acyl-CoA synthetase was lower (P = 0.02) for callipyge lambs at 73 kg.. Serum concentrations of insulin were not affected by genotype (P > 0.20). Serum insulin in non-fasted callipyge lambs was not affected by body weight, but increased with weight in non-fasted normal lambs (P = 0.03). Two-day fasted lambs had decreased serum insulin in both genotypes, which increased (P = 0.03) similarly with body weight for both genotypes. Serum IGF-I was greater (P = 0.09) in normal lambs at 73 kg, whereas IGF-I in 2-d fasted callipyge lambs was greater (P = 0.03) than normal lambs. No genotype effects were observed for the relative proportions of the IGF-binding proteins. We conclude that callipyge lambs had lower lipogenic enzyme activities in adipose tissue than normal lambs, but these changes were not related to serum concentrations of insulin or IGF-I.
Key words: lambs; callipyge; lipogenesis; insulin
Technical Note – Genetic Control of Color in Dorper Sheep and Their Crosses
South African Dorper sheep were imported into the U.S. during the 1990?s, and have generated considerable interest within the American sheep industry. The typical South African Dorper is a white animal with a black head, although both entirely white animals and white animals with red heads also occur. The Dorper breed was derived from crosses between the Dorset and the Blackhead Persian, beginning in the 1940?s (Milne, 2000), and the Dorper color pattern is essentially the same as that of its Blackhead Persian parent. The typical Dorper coat is composed predominantly of hair fibers, although many animals possess a detectable proportion of wool fibers and some have a distinctively wooly coat (Cloete et al., 2000). Shedding of wool fibers, when they are present, is common, and shearing is not practiced in commercial flocks.
Research Note – Influence of Supplement Form on Ewe Performance and Reproduction
Supplementing ewes grazing dormant rangeland pastures with protein is a common practice in the Northern Great Plains. Supplement form can impact individual animal intake and performance. Ducker et al. (1981) reported that 19 % of 2,931 grazing ewes failed to consume any supplements when offered supplement in block form. Taylor et al. (2000) reported that only 2 % of ewes given pellets were non-consumers, while 35 % of those offered blocks were non-consumers. Bowman and Sowell (1997) summarized a number of ewe studies and reported that the mean coefficient of variations in supplement intake by ewes that were hand-fed pelleted supplements were significantly less than those reported for block-fed ewes. However, few studies have examined how these two-supplement forms affect ewe performance when fed under commercial conditions. The objective of this study was to compare how supplement form (pellets or cooked molasses block) influenced ewe body weight, body condition, wool characteristics, and lambing percentage.
Volume 17, No. 1
Sheep & Goat Research Journal. Volume 17, No. 1: 2001
Advantages of Multispecies Grazing: Perceptions of Idaho and Wyoming Producers
This study reports findings of a survey aimed at examining whether complementarity in sheep and cattle production is recognized by producers and is an important factor in the maintenance of both enterprises by ranchers in ldaho and Wyoming. Over 80% of respondents felt their cattle and sheep enterprises had some degree of integration and complemented one another. This complementarity was created by the dietary selection, grazing behavior and the social structure of sheep and cattle. While the sheep enterprise was the most labor intensive, labor and equipment requirements of the two enterprises were seen as being complementary. Profitability and cash flow additionally were aided by the diversification provided from maintaining both a sheep and cattle enterprise. The majority of producers felt that fluc tuations in prices and production between sheep and cattle enterprises were somewhat offsetting. While 70% of respondents felt sheep had been historically more profitable than cattle, more respondents assigned a higher probability that they would abandon the sheep business before the cattle business because of recent trends in the industry.
Key Words: Survey, Multispecies grazing, Complementary products, Diversification
Prickle Factor in Fleeces of Performance-tested Fine-wool Rams
Prickle factor (PF, % of fibers > than 30 µm) is an indicator of the relative comfort of wool fabrics worn next to the skin. Fiber diameter distributions were measured (with an Optical Fibre Diameter Analyser) in three consecutive years on core samples of unskirted fleeces from 524 fine-wool rams completing a central per fonnance test. These measurements were used to establish PF, average fiber diameter (AFD), SD, and CV in fleeces produced under the unfavorable (from a wool fineness and uniformity perspective) test conditions and to determine relationships among PF and fiber fineness and variability. As part of the normal performance test routine, AFD, SD, and CV were measured on side and britch samples for each fleece. The AFD of side samples was used in the index of overall merit and AFD of side and britch samples constituted an independent rejection criteria for ram certification. Core sample PF, AFD, SD, and CV averaged 5.5%, 22.3 µm, 4.4 µm, and 20.0″/o and ranged from 0.4 to 25.3%, 17.3 to26.8 µm 3.1 to 6.4 µm,and 15.2 to28.6%, respectively. The PF, SD, and CV did not differ among years (P > 0.05). It has been suggested that only wools having low PF (< 2%) be used in apparel worn next to the skin. Only eighteen percent of the fleeces were in this category. Stepwise multiple regression analysis was used to predict PF using all measured variables plus AFD squared (AFD’) and differences between side and britch AFD resulted in core AFD’, core AFD, britch SD, core SD, side CV, and core CV entering the equation. No other variable met the 0.01 significance level for entry into the model. Partial r2 values for the first three variables were 0.82, 0.10, and 0.03, respectively. This result was essentially unchanged when fleeces (349) having core, side, and britch AFD > 23.6, 24.9, and 27 .8 µm, respectively (i.e., from coarse, uncertifiable rams) were excluded from the analysis. Most of the variability in PF can be accounted for by core data alone, i.e., PF = 199.57 + 0.46*AFD’ – l 9.33*AFD + 6.0 l *SI_) – l.O I *CV, r’ = 0.94.
Key Words: Prickle factor, Wool, Ram performance testing
U.S. Lamb Demand
Understanding major determinants of, and trends in consumer demand for lamb is critical for the industry to develop appropriate production and marketing strategies. Little research has empirically determined aggregate lamb demand. This study estimates a quarterly lamb demand model to assess major determinants over time. Per capita lamb consumption appears to be more responsive to lamb price than previous studies have concluded. When retail lamb price increases, comparable percentage declines in per capita consumption are likely. Beef is a significant substitute for lamb suggesting continued efforts to make lamb price competitive with other meats is important. Lamb demand tends to decline when consumer incomes and associated lifestyles change. This suggests that, in order to increase lamb demand, lamb products that are compatible with high-income consumer lifestyles are essential.
Key Words: Lamb demand, Demand index, U.S. lamb demand
Comparison of Three Measuring Techniques for Staple Length and Strength in U.S. Wool
Twenty-nine consignments of greasy wool in Texas warehouses were used to compare three measuring techniques for staple length (SL) and strength (SS) and to assist the U.S. wool industry in deciding which techniques to adopt for commercial testing. Samples (-IO lb/lot) were obtained using a bale grab sampler and were subsampled at the Texas Agricultural Experiment Station (TAES) Wool and Mohair Research Laboratory (WMRL) to provide three sets of comparable subsamples. One complete set of subsamples (29 subsamples x 65 staples/ subsample = 1,885 staples) was sent to the Australian Wool Testing Authority (AWTA) for measurement using the Automatic Tester for Length and Strength (ATLAS) while another set was sent to SGS Wool Testing Services (SGS) in New Zealand for testing with the Agritest Staple Breaker Model 2. A third set was measured at WMRL using the American Society for Testing and Materials (ASTM) manual method for SL and an Agritest Staple Breaker (manual model) for SS. Each testing lab used the same wool base and vegetable matter base values to convert “greasy” to “clean” SS. Paired t tests and linear regression analyses were conducted to test for differences and calculate r values between test methods. Warehouse personnel provided visual estimates of SL. Mean values of SL determined by AWTA and the visual assessments were not different (3.20 and 3.21 in, respectively, P > 0.05; r2 = 0.63). Measurements of SL made by SGS and WMRL were not different (3.07 and 3.12 in, respectively, P > 0.05; r2 = 0.74) but were shorter (P < 0.05) than the AWTA and visual results. Mean values of variability in staple length (CV) were not different (P > 0.05) among the three measuring techniques. The AWTA and SGS means of SS were not different (32. I and 31.8 N/ktex [a textile measure of strength, newtons per kilotex, literally kilogram force per unit of staple thickness expressed in ktex, kg per km], respectively, P > 0.05; r = 0.41). The WMRL meanvalue, 41.7 N/ktex, for SS was greater (P < 0.05) than the other two labs, which strongly suggests that either the manual instrument and/or the WMRL technique produced excessively high values. Further testing incorporating a broader cross-section of U.S. wools is required before an authoritative recommendation can be made to the U.S. wool trade.
Key Words: Staple length, Staple strength, Wool
Research Notes – Survival and Serum IgG Levels in Twin Born Lambs Supplemented with Vitamin E Early in Life
Key Words: Lambs, Vitamin E, Lamb survival, Immunoglobulin G
Lamb mortality is a major factor limiting profitability in sheep operations. Estimates of pre-weaning losses range from 15 to 51% (Rook, 1997), with mortalities as high as 35% considered normal for large sheep operations (Rowland et al., 1990). Rowland et al. (1990) also reported that 50% of mortality occurs in the first 24 hours of life.
Supplemental vitamin E given orally to the ewe during late gestation has been shown to decrease lamb mortality (Kott et al., 1998). In addition, when lambs were injected with vitamin E shortly after birth, Gentry et al. (1992) noted an increase in lamb serum immunoglobulin G (IgG) concentration that could be indicative of enhanced immune function.
(Besser and Gay, 1994). However, no advantages in survival or lamb body weight gain were observed when supplemental vitamin E was given to lambs at birth (Gentry et al., 1992; Williamson et al., 1996).
Research Notes – Is There an Influence of Individual Rams on Ewe Prolificacy?
Key Words: Ram, ewe, prolificacy, lambing rate
Previous studies have shown that ram introduction near the onset of the breeding season stimulates the initiation of estrous cycles (Sebastian and Inskeep, 1988)and ram libido influences flock conception and flock lambing rates (Fitzgerald, 1992). Twin- and triplet-born rams produce more multiple births than single-born sires (Hodgson et al., 1965; Vakil et al., 1968; Botkin et al., 1988), an effect generally attributed to increased libido (Fitzgerald, 1992) and serving capacity (i.e. testis size; Snowder et al., 1981). Sexual behavior also varies among individual rams (Price, 1987; Fitzgerald and Perkins, 1993; Alexander et al., 1999) and among males of other species (Meisel and Sachs, 1994).
Ovulation rate and prolificacy of ewes are characterized as being lowly heritable characteristics (Botkin et al., 1988) inherent to a ewe’s reproductive cycle. In spite of t h is generalization, limited data (Hodgson et al., 1965; Botkin et al., 1988; Burfening and Davis, 1996) and emperical observations support a role for the male in influencing prolificacy of individual ewes. The observation that clitoral stimulation advanced timing of ovulation in cows (Randel et al., 1973) supports the concept that stimuli associated with mating may influence time and perhaps rate of ovulation in spontaneously ovulating species such as cattle or sheep. Alternatively, in vitro fertilization studies with rabbits led to the conclusion that semen from selected bucks differentially influenced embryo survival in vivo (Burfening and Ulberg, 1968). More recently, “service sire” was indicated as a significant source of variation for number of lambs born per ewe exposed (Burfening and Davis, J 996) and a paternal effect on initiation and length of the S-phase of embryo development was reported for bulls (Eid et al., 1994). Therefore, the precedence for a sire effect on number of off spring born to individual ewes exists, but mechanisms through which such an effect may be mediated remain an enigma.
Technical Notes – Enterprise Budgeting for Ewe Flock Operations
Enterprise budgeting is a tool producers can use to evaluate current and alternative enterprises for profitability. Enterprise budgets are typically completed for operations that are not undergoing significant change. This ignores any transition or implementation phase necessary to make changes or start an entirely new enterprise. While some changes may take several years to implement, others can be accomplished in one production period. EweCost is a tool that assists sheep producers in analyzing current and potential future alternative operating procedures for an ewe flock. The end point in this enterprise is feeder lambs and wool.
The EweCost program is divided into four sections; 1) revenue calculation and inventory check, 2) enterprise operating costs, 3) enterprise ownership costs, and 4) results. To save space, only a portion of the results and input are presented here. Not shown are inputs required for the leasing analysis, sensitivity tables that vary prices, weights and weaning percentage from the results section, graphs showing breakdowns of income and expense and the results of the share and cash lease analysis. While there is extensive use of color in the software, some information that color is designed to enhance is lost when printed in black and white. Information the user is either allowed or required to enter is displayed in blue text and outlined in double lined boxes. Numbers or labels outside of a double lined box are calculated or fixed and cannot be changed.
Volume 10, No. 1
Sheep & Goat Research Journal. Volume 10, No. 1: 1994
Special Edition: The Role of Sheep Grazing in Natural Resource Management
The Role of Grazing Sheep in Sustainable Agriculture
The world has challenged agriculture to continue to produce an abundance of food and fiber for an ever expanding population. The furor, developed over improving the global environment, dictates this production occur in a “clean” environment considered “safe” for all living organisms.
The United States has developed an efficient, highly productive food and fiber system envied by the world because consumers spend a lower percentage (11.8) of their income for food than any country in the world (Hess, 1991). However, the technology used in this development did not, in many cases, anticipate the potential social, environmental and health costs. An outcome of this magnificent progression is sustainable agricultural systems, which advocate the use of fewer exogenous materials, in smaller amounts, to maintain land productivity. Sustainable systems may require reduced grain feeding to animals an increased use of crop residue; and waste feed materials, reduced use of chemical fertilizers and greater reliance on legumes, reduced use of pesticides and herbicides, more extensive use of soil and water conservation measures and careful attention to water quality. This dichotomy, to produce more with Jess, points to the birth of significantly altered agricultural production systems in the future. One alteration will be a greater reliance on forages for food and fiber production. One animal which can contribute to feeding and clothing the world population in the future, because of its characteristic efficient use of forages in a sustainable environment, is the sheep.
Multispecies Grazing: The Ecological Advantage
Grazing of several species of herbivores on the same area typically results in more efficient utilization of forage resources and increases sustainable production. These benefits are the result of different dietary habits of the animals because plants avoided by one kind of livestock may be relished by another. Differences in dietary ha bits are related to the physical limitation on the ability to select and the physiological limitation on the ability to detoxify forage phytochemicals. Compared to cattle, sheep diets usually have more forbs and less grass. Sheep can graze lower in the forage canopy, have a greater ability to select from a fine-scale mixture and have a more varied diet than cattle. As available forage decreases, dietary overlap between sheep and cattle tends to decrease because cattle shift their diet to lower quality but mo.re available forage while sheep can continue to select their preferred diet. Averaged across a wide range of studies, multispecies grazing increased meat production by 24% compared to cattle-only grazing and by 9% compared to sheep-only grazing. This advantage is usually caused by both increased individual animal performance and increased carrying capacity. Despite the potential increases in economic and biological efficiency, multispecies grazing is not widely practiced. This valuable management practice should be promoted based on its ability to meet societal goals for more environ mentally sound agricultural production practices. Compared to single species grazing, multiple species of animals use vegetation resources more uniformly, which can enhance ecosystem stability.
Key words: sheep, cattle, goats, diet selection, diet overlap, foraging behavior, sustainable agriculture.
Sheep Grazing and Riparian and Watershed Management
This study was conducted to evaluate the reproductive performance of two-yr-old, sexually na?ve rams of different genotypes. Eight rams of each Awassi (A), F1 Charollais- Awassi (CA) and F1 Romanov-Awassi (RA) genotypes were subjected to sexual performance tests by being individually exposed to two estrous Awassi ewes for five, 20-min periods. Body weight (BW), body condition score (BCS), scrotal circumference (SC) and semen characteristics were recorded every 2 wk for 2 mo prior to sexual performance testing. Awassi rams engaged in more leg-kicking bouts (P < 0.01) than RA rams. Mounting frequency, raising the fat tail of females, and ejaculation rate were greater (P < 0.05) in A than in CA and RA rams. No genotype x test day interactions were detected, however, test day influenced (P = 0.05) ejaculation rate. Rams of the CA genotype had greater BW (P < 0.01) than RA and A. The CA rams had greater SC (P < 0.01) than A rams and higher BCS (P < 0.01) than RA rams. The RA rams had greater (P < 0.05) semen mass motility than A and lower (P < 0.05) percentage of abnormal spermatozoa than A and CA rams. Additionally, semen concentration tended (P < 0.10) to be greater in RA than in A and CA rams. Results of the present study indicate that RA rams tend to have better semen characteristics, while Awassi rams had better sexual performance when mated with fat-tailed females than the CA and RA genotypes, which may necessitate the use of artificial insemination during crossbreeding programs.
Sheep Grazing as a Range Improvement Tool
Grazing is an integral and natural process on rangelands. Long-term studies have concluded that grazing can be managed to manipulate the vegetative composition of rangelands. There are two principle criteria that must be implemented to achieve improvement. First, grazing must be managed by established goals and realistic specific objectives. Without achievable goals and clearly stated objectives grazing would be unmanaged and extensive experiences have illustrated that unmanaged grazing by domestic and wild herbivores can result in catastrophe. Basic principles for establishing these goals and objectives are well documented. Second, improvement should be defined as attaining desired objectives for the rangeland resource. In some instances, improvement will equate with increased forage available for grazing livestock. In other instances, improvement will be based on non-livestock forage criteria. In all cases the resource will be benefitted and livestock will maintain an integral role in the renewable use and sustained management of rangelands.
Key words: rangelands, sheep, range improvement, grazing management.
Prescribed Sheep Grazing to Enhance Wildlife Habitat on North American Rangelands
Prescribed sheep grazing is a promising tool for enhancing all four wildlife habitat essentials: 1) food, 2) water, 3) cover, and 4) space. Sheep grazing is a low-cost, low-energy input form of habitat manipulation that can be implemented on a landscape scale for many wild life species’ in diverse types of habitat. Through the manipulation of sheep foraging behavior, rangeland sheep grazing can purposely and favorably alter the yield, accessibility and nutritive quality of forage; the abundance of prey; the availability of water; the availability of thermal cover and security cover; and the amount of space available to wildlife. It is important to note, however, that these habitat alterations will only enhance a fauna’s population if the limiting habitat factor is improved. Trade-offs must also be considered because it is impossible to maximize the habitat of all wildlife at once. Any alteration to one or more of the habitat essentials requisitely improves the habitat of some fauna yet simultaneously and inevitably degrades the habitat of others. Biological diversity of many terrestrial ecosystems can be improved by using prescribed sheep grazing to create diverse arrays of the four habitat essentials.
Sheep Grazing as a Brush and Fine Fire Fuel Management Tool
Rangelands throughout the U.S., as wet as the rest of the world, play a major role in supplying human populations with animal and plan t products, recreation and water and habitat for wildlife. A pivotal element in determining the actual use for any particular rangeland resource is the vegetation composition (i.e., the structure and species composition of range vegetation is the primary driving force in land use and management). A vegetation shift from grassland to woodland has been documented in most rangelands of the U.S. Increases of woody plants reduces livestock production potential, greatly alters wildlife habitat, reduces water availability to both rural and urban uses, increases soil erosion potential and can lower the overall recreational desirability of a region. Although there is not unanimous agreement, most authors have attributed this woody plant increase to grazing disturbance (heavy stocking), which reduced both fire frequencies and the removal of competition from grasses. Even though excessive livestock grazing has contributed to the increase of woody plants on rangeland, proper management based on a knowledge of the foraging process can be used to direct plant succession towards an improved range condition. Using sheep to manipulate vegetation appears to be an important part of the grazing management needed to reach this goal.
Key words: biological, brush management, fire, grazing, sheep.
Sheep as a Sulvicultural Management Tool in Temperate Conifer Forest
Sheep grazing is a traditional use of temperate coniferous forest in the United States and Canada. Like any management tool, prescription sheep grazing can be misused. Unacceptable damage to conifer regeneration can occur when sheep are poorly controlled or plantations are overgrazed. Relative attractiveness of trees compared to other forage available to sheep changes seasonally. Trees are most likely to be browsed during the spring when lush new twig and needle growth is present or any time that other green feed becomes scarce. Sheep browsing of young trees has relatively little impact upon conifer growth unless the terminal leader or almost all of current year’s lateral branches are consumed. Properly applied sheep grazing often reduces competition between trees and other ground vegetation, thus increasing tree growth. Although prescriptions have yet to be fully determined for many forest sites, results to date suggest that prescription grazing may provide a socially acceptable alternative to herbicides for conifer release in many areas.
Key words: biological control, integrated pest management, brush livestock grazing, agroforestry.
Sheep: A Method for Controlling Rangelands Weeks
Noxious rangeland weeds are difficult to control. Where the use of many control treatments are limited by environmental and economic constraints, sheep grazing is a potential weed control method. Sheep possess many traits that enable them to be used to control noxious weeds and reduce poisonous plant infestations. Currently, sheep arc used to control leafy spurge, spotted knapweed, tall larkspur, tansy ragwort and other weeds. In some cases, landowners assess renters a lower fee when their sheep graze weed-infested rangelands. Federal land management agencies often do not charge any fee when sheep grazing is used to control noxious weeds. The value of sheep as a weed control method, and subsequently their use on rangelands, is expected to increase in the future.
The Role of Sheep and Sheep Products in Waste Management
Our appreciation of the potential role and value of sheep and their products in the handling of waste materials is still in its infancy. A limited number of novel applications are currently in use. However, with the increased interest in biological solutions to environmental problems, additional roles for sheep products will undoubtedly emerge. Key words: biological control, integrated pest management, brush livestock grazing, agroforestry.