Multitrait Estimation of Relationships of First-Lactation Yields to Body Weight Changes in Holstein Heifers

摘要: An experimental population of 994 Holstein heifers from 56 sires was used to estimate simultaneously heritabilities and genetic phenotypic correlations between first-lactation yields prepartum postpartum weight changes. Variance covariance components were estimated by the multitrait restricted maximum likelihood method. Heritability estimates .09, .15, .32 for milk, protein, fat yields. ranged .20 .34 body weights changes first lactation. Weight gain 350 462 d age highly correlated, genetically phenotypically, with Genetic at calving 56, 112, 168, 224, 280 positive, suggesting that larger had higher lactation In contrast, gains during negative, indicating high-producing gained less than low-producing heifers. Heifers lost an average 23 kg thereafter. On scales, more onward smaller