Sire and sire-feeding regimen interaction effects on lactation, growth, and carcass traits in dairy cattle

Data from the University of Illinois dairy herd were used to estimate heritabilities of lactation yield, growth rate, and carcass traits and genetic correlations among them and to evaluate the importance of sire and of interaction of sire with feeding regimen for these traits. Heritabilities for lactation, growth, and carcass traits were small or moderate. Genetic correlations of lactation with carcass traits were moderate negative or large positive. Genetic correlations of estimated average daily gain with lactation and carcass traits could not be estimated. Variance for interaction of sire with feeding was large relative to sire variance for estimated average daily gain. Similarly, variance for interaction of sire with feeding regimen was large for back fat thickness, chilled carcass weight, dressing percentage, maturity score, and yield grade. Interaction of sire with feeding should be considered in genetic studies or in sire evaluation for some carcass traits and average daily gain.