Sheep & Goat Research Journal. Volume 23, 2008

Contents

Nutrient Utilization in Polypay and Percentage White Dorper Lambs Fed a High-Roughage and a High-Concentrate Diet
Author: A.K. Lunsford, D.G. Ely, D.K. Aaron, M.M. Simpson and R.A. Zinner
PRNP Genotype and Sale Price - Associations of prion protein genotype with sale price in a flock of purebred Polled Dorsets
Author: C.D. Dechow, H.W. Harpster, S.R. Sieuve de Menezes and J.R. Werner
The Yellowing Propensity of Rambouillet Wool
Author: B.A. Cameron and R.H. Stobart
Feeding of DDGS in Lamb Rations
Author: C.S. Schauer, M.M. Stamm, T.D. Maddock and P.B. Berg

Article Summaries

Nutrient Utilization in Polypay and Percentage White Dorper Lambs Fed a High-Roughage and a High-Concentrate Diet

Author: A.K. Lunsford, D.G. Ely, D.K. Aaron, M.M. Simpson and R.A. Zinner
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Summary

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

Author: C.D. Dechow, H.W. Harpster, S.R. Sieuve de Menezes and J.R. Werner
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Summary

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

Author: B.A. Cameron and R.H. Stobart
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Summary

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

Author: C.S. Schauer, M.M. Stamm, T.D. Maddock and P.B. Berg
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Summary

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