| Feed intake of sheep as affected by body weight, breed, sex, and feed composition. | |
| | |
MedLine Citation:
|
PMID: 19897642 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
The hypotheses tested were that genetic size-scaling for mature BW (A, kg) would reduce variation in intake between kinds of sheep and that quadratic polynomials on u = BW/A with zero intercept would provide good descriptions of the relationship between scaled intake (SI, g/A(0.73) d) and degree of maturity in BW (u) across feeds of differing quality. Both sexes of Suffolk sheep from 2 experimental lines (n = 225) and from 3 breed types (Suffolk, Scottish Blackface, and their cross; n = 149) were recorded weekly for ad libitum feed intake and BW; recording of intake was from weaning through, in some cases, near maturity. Six diets of different quality were fed ad libitum. The relationship between intake and BW on a given feed varied considerably between kinds of sheep. Much, but not all, of that variation was removed by genetic size-scaling. In males, the maximum value of SI was greater than in females (P = 0.07) and was greater in Suffolk than in Scottish Blackface, with the cross intermediate (P = 0.025); there was no difference between the 2 Suffolk lines used (P = 0.106). The quadratic polynomial model, through the origin, was compared with a split-line (spline) regression for describing how SI varied with u. For the spline model, the intercept was not different from zero in any case (P > 0.05). The values of u at which SI achieved its maximum value (u* and SI*) were calculated. Both models fit the data well; the quadratic was preferred because it predicted that SI* would be achieved within the range of the long-run data, as was observed. On a high quality feed, for the spline regression, u* varied little around 0.434 (SD = 0.020) for the 10 different kinds of sheep used. For the quadratic, the mean value of 0.643 (SD = 0.066) was more variable, but there were no consistent effects of kind of sheep. The values of u* and SI* estimated using the quadratic model varied among the 6 feeds: 0.643 and 78.5 on high quality; 0.760 and 79.6 on medium protein content; 0.859 and 73.3 on low protein content; 0.756 and 112 on a low energy content feed; 0.937 and 107 on ryegrass; and 1 (forced, as the fitted value of 1.11 was infeasible) and 135 on Lucerne. The value of u* tended to increase as feed digestibility decreased. We conclude that genetic size-scaling of intake is useful and that a quadratic polynomial with zero intercept provides a good description of the relationship between SI and u for different kinds of sheep on feeds of different quality. Up to u congruent with 0.45, intake was directly proportional to BW. |
| | |
Authors:
|
R M Lewis; G C Emmans |
Publication Detail:
|
Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2009-11-06 |
Journal Detail:
|
Title: Journal of animal science Volume: 88 ISSN: 1525-3163 ISO Abbreviation: J. Anim. Sci. Publication Date: 2010 Feb |
Date Detail:
|
Created Date: 2010-01-28 Completed Date: 2010-04-09 Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 8003002 Medline TA: J Anim Sci Country: United States |
Other Details:
|
Languages: eng Pagination: 467-80 Citation Subset: IM |
Affiliation:
|
Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. rmlewis@vt.edu |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Animal Feed* Animal Husbandry Animals Body Size / genetics, physiology Body Weight / genetics, physiology* Breeding Dietary Proteins / metabolism Eating / genetics, physiology* Female Genotype Hybridization, Genetic / genetics, physiology Male Sex Factors Sheep / genetics, physiology* |
| Chemical | |
Reg. No./Substance:
|
0/Dietary Proteins |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Differential expression of liver proteins in Chianina and Holstein young bulls.
Next Document: Short-term Signatures of Evolutionary Change in the Salmonella enterica serovar Typhimurium 14028 Ge...