Document Detail

Genetic parameters of legendre polynomials for first parity lactation curves.
MedLine Citation:
PMID:  11104284     Owner:  NLM     Status:  MEDLINE    
Variance components of the covariance function coefficients in a random regression test-day model were estimated by Legendre polynomials up to a fifth order for first-parity records of Dutch dairy cows using Gibbs sampling. Two Legendre polynomials of equal order were used to model the random part of the lactation curve, one for the genetic component and one for permanent environment. Test-day records from cows registered between 1990 to 1996 and collected by regular milk recording were available. For the data set, 23,700 complete lactations were selected from 475 herds sired by 262 sires. Because the application of a random regression model is limited by computing capacity, we investigated the minimum order needed to fit the variance structure in the data sufficiently. Predictions of genetic and permanent environmental variance structures were compared with bivariate estimates on 30-d intervals. A third-order or higher polynomial modeled the shape of variance curves over DIM with sufficient accuracy for the genetic and permanent environment part. Also, the genetic correlation structure was fitted with sufficient accuracy by a third-order polynomial, but, for the permanent environmental component, a fourth order was needed. Because equal orders are suggested in the literature, a fourth-order Legendre polynomial is recommended in this study. However, a rank of three for the genetic covariance matrix and of four for permanent environment allows a simpler covariance function with a reduced number of parameters based on the eigenvalues and eigenvectors.
M H Pool; L L Janss; T H Meuwissen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of dairy science     Volume:  83     ISSN:  0022-0302     ISO Abbreviation:  J. Dairy Sci.     Publication Date:  2000 Nov 
Date Detail:
Created Date:  2001-02-28     Completed Date:  2001-03-15     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985126R     Medline TA:  J Dairy Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2640-9     Citation Subset:  IM    
Department of Genetics and Reproduction, Institute for Animal Science and Health (ID-Lelystad), The Netherlands.
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MeSH Terms
Dairying / methods
Lactation / genetics*
Milk / secretion*
Models, Genetic
Models, Statistical
Parity / genetics*
Regression Analysis

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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