Sheep & Goat Research Journal. Volume 25, 2010

Contents

A Review: The Use of Livestock Protection Dogs in Association with Large Carnivores in the Rocky Mountains
Author: C. Urbigkit and J. Urbigkit
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...
Author: D.T. Yates, L.J. Yates, A.R. Otis, C.A. Warner, R.A. Halalsheh, D.M. Hallford and T.T. Ross
Feedlot Performance, Carcass Characteristics, and Muscle CLA Concentration of Lambs Fed Diets Supplemented with Safflower Seeds and Vitamin E
Author: R.W. Kott, L.M.M. Surber, A.V. Grove, P.G. Hatfield, J.A. Boles, C.R. Flynn and J.W. Bergman
Pregnancy rates after ewes were treated with estradiol-17β and oxytocin
Author: G.S. Lewis
Can Sheep and Cattle Rumen Microorganisms be Conditioned to Invasive Weeds?
Author: T.R. Whitney and B.E. Olson
Manipulating Sheep Browsing Levels on Coyote Willow (Salix exigua) with Supplements
Author: A.L. Lujan, S.A. Utsumi, S.T. Smallidge, T.T. Baker, R.E. Estell, A.F. Cibils and S.L. Ivey
Effects of Physical Isolation on Serum and Salivary Cortisol and Components of Complete Blood Counts in Yearling Ewes
Author: D.T. Yates, A.R. Otis, C.A. Warner, L.J. Yates, R.A. Halalsheh, M.B. Horvath, D.M. Hallford and T.T. Ross
Research Note: Sheep Antiserum as an Antibody Supplement in Newborn Lambs
Author: J.L. Pommer
Substituting Corn Dried Distillers Grains for Cottonseed Meal in Lamb Finishing Diets: Carcass Characteristics, Meat Fatty Acid Profiles, and Sensory Panel Traits
Author: T.R. Whitney and K.W. Braden
Effect of Finishing Crossbred Meat Goats with a Similar Total Quantity of Finisher Ration Over Variable Duration
Author: M. Lema, C. Pierfax, S. Kebe and N. Adefope
Evaluation of Ultrasonography to Measure Fetal Size and Heart Rate as Predictors of Fetal Age in Hair Sheep
Author: R.W. Godfrey, L. Larson, A.J. Weis and S.T. Willard
Protein Supplementation of Low-quality Forage: Influence of Frequency of Supplementation on Ewe Performance and Lamb Nutrient Utilization
Author: C.S. Schauer, M.L. Van Emon, M.M. Thompson, D.W. Bohnert, J.S. Caton and K.K. Sedivec
Effects of Supplemental Cobalt on Nutrient Digestion and Nitrogen Balance in Lambs Fed Forage-based Diets
Author: E.J. Scholljegerdes, W.J. Hill, H.T. Purvis, L.A. Voigt and C.S. Schauer
Effect of Feeding System on Meat Goat Growth Performance and Carcass Traits
Author: C.R. Johnson, S.P. Doyle and R.S. Long

Article Summaries

A Review: The Use of Livestock Protection Dogs in Association with Large Carnivores in the Rocky Mountains

Author: C. Urbigkit and J. Urbigkit

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Summary

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...

Author: D.T. Yates, L.J. Yates, A.R. Otis, C.A. Warner, R.A. Halalsheh, D.M. Hallford and T.T. Ross

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Summary


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

Author: R.W. Kott, L.M.M. Surber, A.V. Grove, P.G. Hatfield, J.A. Boles, C.R. Flynn and J.W. Bergman

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Summary

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

Author: G.S. Lewis

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Summary

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?

Author: T.R. Whitney and B.E. Olson
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Summary

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

Author: A.L. Lujan, S.A. Utsumi, S.T. Smallidge, T.T. Baker, R.E. Estell, A.F. Cibils and S.L. Ivey

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Summary

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

Author: D.T. Yates, A.R. Otis, C.A. Warner, L.J. Yates, R.A. Halalsheh, M.B. Horvath, D.M. Hallford and T.T. Ross

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Summary

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

Author: J.L. Pommer

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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

Author: T.R. Whitney and K.W. Braden

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Summary

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

Author: M. Lema, C. Pierfax, S. Kebe and N. Adefope

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Summary

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

Author: R.W. Godfrey, L. Larson, A.J. Weis and S.T. Willard

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Summary

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

Author: C.S. Schauer, M.L. Van Emon, M.M. Thompson, D.W. Bohnert, J.S. Caton and K.K. Sedivec

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Summary

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

Author: E.J. Scholljegerdes, W.J. Hill, H.T. Purvis, L.A. Voigt and C.S. Schauer

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Summary

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

Author: C.R. Johnson, S.P. Doyle and R.S. Long

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Summary

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