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Modelling the growth curve of Maine-Anjou beef cattle using heteroskedastic random coefficients models

  • Christèle Robert-GraniéEmail author
  • Barbara Heude
  • Jean-Louis Foulley
Open Access
Research

Abstract

A heteroskedastic random coefficients model was described for analyzing weight performances between the 100th and the 650th days of age of Maine-Anjou beef cattle. This model contained both fixed effects, random linear regression and heterogeneous variance components. The objective of this study was to analyze the difference of growth curves between animals born as twin and single bull calves. The method was based on log-linear models for residual and individual variances expressed as functions of explanatory variables. An expectation-maximization (EM) algorithm was proposed for calculating restricted maximum likelihood (REML) estimates of the residual and individual components of variances and covariances. Likelihood ratio tests were used to assess hypotheses about parameters of this model. Growth of Maine-Anjou cattle was described by a third order regression on age for a mean growth curve, two correlated random effects for the individual variability and independent errors. Three sources of heterogeneity of residual variances were detected. The difference of weight performance between bulls born as single and twin bull calves was estimated to be equal to about 15 kg for the growth period considered.

Keywords

heteroskedastic random coefficient model EM-REML robust estimators growth curve Maine-Anjou breed 

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Copyright information

© INRA, EDP Sciences 2002

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Authors and Affiliations

  • Christèle Robert-Granié
    • 1
    Email author
  • Barbara Heude
    • 2
  • Jean-Louis Foulley
    • 2
  1. 1.Station d'amélioration génétique des animauxInstitut national de la recherche agronomiqueCastanet-TolosanFrance
  2. 2.Station de génétique quantitative et appliquéeInstitut national de la recherche agronomiqueJouy-en-Josas CedexFrance

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