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Application de la méthode du maximum de vraisemblance restreint (REML) à l’estimation des paramètres génétiques des trois premières lactations en race montbéliarde.

Abstract : Genetic parameters for the first three lactations have been estimated for the main dairy traits (milk, fat, protein and useful yields adjusted for lactation length, fat and protein contents). Two data sets were analysed, including records on 30 751 cows born from 128 young sires and 52 proven sires. Daughters’ performances from the most widely used proven sires were incorporated in order to improve the degree of connectedness among herds. The model fitted young sires as random and proven sires, herd-year, season-year of calving, age at first calving and length of the previous lactation as fixed effects. Relationships among bulls were included. Analysis was by restricted maximum likelihood using an EM-related algorithm and a Cholesky transformation. All genetic correlations were larger than 0.89. Correlations between the first and third lactations were slightly lower than the others. Heritabilities of milk, fat, protein and useful yields ranged from 0.17 to 0.27. Phenotypic correlations between successive lactations were higher than 0.6 and those between lactations 1 and 3 lower than 0.55. Heritabilities of fat and protein contents were higher than 0.44 with phenotypic correlations being stable at about 0.70. The "repeatability model" which considers all lactation records as a single trait can be considered in genetic evaluation procedures for dairy traits without significant losses in efficiency.
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  • HAL Id : hal-02718531, version 1
  • PRODINRA : 24159

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Catherine Beaumont. Application de la méthode du maximum de vraisemblance restreint (REML) à l’estimation des paramètres génétiques des trois premières lactations en race montbéliarde.. Genetics Selection Evolution, BioMed Central, 1989, 21 (4), pp.493-506. ⟨hal-02718531⟩

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