Document Detail


Parameter estimates for greasy fleece weight of Rambouillet sheep at different ages.
MedLine Citation:
PMID:  10947096     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Variance components for greasy fleece weight in Rambouillet sheep were estimated. Greasy fleece weight was modeled either as repeated measurements on the same trait or as different traits at different ages. The original data were separated according to the age of the ewe at shearing into three classes; 1 yr, 2 and 3 yr, and older than 3 yr. An animal model was used to obtain estimates of genetic parameters with a REML algorithm. Total numbers of animals in pedigrees for the different age classes were 696, 729, and 573, respectively, and 822 for the repeated measures model across ages. The animal model included direct genetic, permanent environmental, and residual environmental random effects and fixed effects for age of ewe, shearing date as contemporary group, and number of lambs born. Days between shearings was used as a covariate. Single-trait analyses were initially done to obtain starting values for multiple-trait analyses. A repeated measures model across ages was also used. Estimates of heritability by age group were .42, .50, and .58 from three-trait (age class) analyses and for the repeated measures model the estimate was .57. Estimates of genetic correlations between fleece yields for 1 yr and 2 and 3 yr, 1 yr and >3 yr, and 2 and 3 yr and >3 yr classes were .88, .89, and .97, respectively. These estimates of genetic correlations suggest that a repeated measures model for greasy fleece weight is adequate for making selection decisions.
Authors:
J W Lee; D F Waldron; L D Van Vleck
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of animal science     Volume:  78     ISSN:  0021-8812     ISO Abbreviation:  J. Anim. Sci.     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2000-09-12     Completed Date:  2000-09-12     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  8003002     Medline TA:  J Anim Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2108-12     Citation Subset:  IM    
Affiliation:
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
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MeSH Terms
Descriptor/Qualifier:
Aging / physiology*
Animals
Female
Hair / physiology*
Male
Models, Biological
Organ Size
Sheep / physiology*

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