Sheep & Goat Research Journal. Volume 30, 2015

Contents

Genetic Evaluation of Weaning Weight and the Probability of Lambing at 1 Year of Age in Targhee Lambs
Author: D.P. Kirschten, D.R. Notter, A.R. Gilmour, G.S. Lewis and J.B. Taylor

Use of Annual Forage Crops as a Late-Season Forage for Pregnant Ewes, Insect Habitat and to Improve Soil Health
Author: J.W. Stackhouse, C.S. Schauer and B.A. Geaumont

Performance and Behavior by Spring-Born Katahdin Lambs Weaned Using Traditional or Fenceline-Weaning Methods in the Morning or Evening
Authors: E.A. Backes, J.D. Caldwell, B.C. Shanks, K.R. Ness, A.N.V. Stewart, D.L. Kreider and M.L. Looper

Movements of Domestic Sheep in the Presence of Livestock Guardian Dogs
Authors: B.L. Webber, K.T. Weber, P.E. Clark, C.A. Moffet, D.P. Ames, J.B. Taylor, D.E. Johnson and J.G. Kie

Gastro-intestinal Parasite (GIP) Infestation and its Associated Effects on Growth Performance of Bucks on a Pasture-based Test in Maryland
Author: K. Nadarajah, S. Schoenian, and D.L. Kuhlers

Effects of Photoperiodic Manipulation of Growth Rate and Ability to Breed Fall-born Ewe Lambs in Spring
Author: M.L. Deacon, M. Knights and E.K. Inskeep

Effects of Fenceline or Traditional Weaning Methods in Drylot on Performance and Behavior by Katahdin Crossbred Lambs
Author: E.A. Backes, B.C. Shanks, J.D. Caldwell, A.L. Bax, T. Wuliji, K.R. Wansing, and J.K. Clark

Article Summaries

Genetic Evaluation of Weaning Weight and the Probability of Lambing at 1 Year of Age in Targhee Lambs

Author: MD.P. Kirschten, D.R. Notter, A.R. Gilmour, G.S. Lewis and J.B. Taylor

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Summary
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.

Key words:
Sheep, Genetics, Growth, Reproduction, Weaning

Use of Annual Forage Crops as a Late-Season Forage for Pregnant Ewes, Insect Habitat and to Improve Soil Health

Author: J.W. Stackhouse, C.S. Schauer and B.A. Geaumont

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Summary
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.

Key words:
Annual Forage, Cover Crop, Insects, Grazing, Sheep, Soil

Performance and Behavior by Spring-Born Katahdin Lambs Weaned Using Traditional or Fenceline-Weaning Methods in the Morning or Evening

Authors: E.A. Backes, J.D. Caldwell, B.C. Shanks, K.R. Ness, A.N.V. Stewart, D.L. Kreider and M.L. Looper

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Summary
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.

Key words:
Behavior, Katahdin, Performance, Weaning

Movements of Domestic Sheep in the Presence of Livestock Guardian Dogs

Authors: B.L. Webber, K.T. Weber, P.E. Clark, C.A. Moffet, D.P. Ames, J.B. Taylor, D.E. Johnson and J.G. Kie

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Summary
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.

Key words:
Behavior, GIS, GPS, Guardian Dog, Predator, Sheep

Gastro-intestinal Parasite (GIP) Infestation and its Associated Effects on Growth Performance of Bucks on a Pasture-based Test in Maryland

Author: K. Nadarajah, S. Schoenian and D.L. Kuhlers

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Summary
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.

Key words:
Gastro-intestinal Parasites, Goats, Performance Testing

Effects of Photoperiodic Manipulation on Growth Rate and Ability to Breed Fall-born Ewe Lambs in Spring

Author: M.L. Deacon, M. Knights and E.K. Inskeep

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Summary
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.

Key words:
Ewe Lambs, Photoperiod, Pregnancy, Puberty, Season

Effects of Fenceline or Traditional Weaning Methods in Drylot on Performance and Behavior by Katahdin Crossbred Lambs

Author: E.A. Backes, B.C. Shanks, J.D. Caldwell, A.L. Bax, T. Wuliji, K.R. Wansin2, and J.K. Clark

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Summary
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.

Key words:
Behavior, Fenceline, Lambs, Weaning