Document Detail

Genetic parameter estimates of portuguese dairy cows for milk, fat, and protein using a spline test-day model.
MedLine Citation:
PMID:  15738256     Owner:  NLM     Status:  MEDLINE    
A spline animal model was fitted to 152,103 test-day milk, fat, and protein yield records from 14,423 first-lactation cows. The models included age at calving and the herd-test-month as fixed effects. Model fitting was carried out using Restricted Maximum Likelihood with ASREML. For milk yield, the heritability at 18 d in milk was 0.19, which increased to the maximum estimated value of 0.23 at midlactation and then decreased. On average, milk, fat, and protein yield heritabilities were 0.22, 0.14, and 0.19, respectively. For milk yield, all correlations were positive and ranged from 0.54 to 0.99 for the genetic component and from 0.32 to 0.78 for the phenotypic component. Genetic correlations were higher than phenotypic ones. For fat and protein yields, all genetic correlations were positive, ranging from 0.43 to 0.99. The phenotypic correlations for fat yield had the lowest correlations of the 3 traits. Curves of estimated breeding values for milk, fat, and protein over lactation had positive deviations from mean curves for sires with high genetic merit, but there was considerable variability in the shapes of the curves for different sires. More research is needed to compare the spline function with other mathematical functions used as submodels of lactation curve.
A M Silvestre; F Petim-Batista; J Colaço
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of dairy science     Volume:  88     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2005 Mar 
Date Detail:
Created Date:  2005-03-01     Completed Date:  2005-07-21     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1225-30     Citation Subset:  IM    
Departamento de Zootecnia-CECAV, Universidade de Trás-os-Montes e Alto Douro 5000-911 Vila Real, Portugal.
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MeSH Terms
Cattle / genetics*,  physiology
Genetic Variation
Lactation / genetics*
Likelihood Functions
Lipid Metabolism
Lipids / analysis*
Milk / chemistry*,  secretion
Milk Proteins / analysis*,  metabolism
Models, Genetic*
Reg. No./Substance:
0/Lipids; 0/Milk Proteins

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