Genetic and phenotypic parameter estimates between production, feed intake, feed efficiency, body weight and linear type traits in first lactation Holsteins

Abstract

Production and feed intake data on 36 115 first lactation Holstein cows obtained from Quebec Dairy Herd Analysis Service were combined with conformation data from the Holstein Association of Canada to estimate genetic correlations among production, energy intake, and conformation traits. Traits considered were 305-d milk yield, 305-d grain energy and total energy intake, feed efficiency (fat corrected milk yield/total energy intake), body weight at calving, capacity, size, stature, rump width and final score. Genetic and phenotypic parameters were estimated using Restricted Maximum Likelihood based on two-trait animal mixed model analyses. The model contained fixed effects of herd-year, season of calving, age of calving, sire group and a random animal genetic effect. Estimates of heritability were within the published range for all traits. Of the conformation traits examined, capacity, size and stature had the highest correlations with body weight, with phenotypic correlations between 0.36 and 0.43, and genetic correlations between 0.61 and 0.79. Feed efficiency was negatively correlated to all body size measures, both phenotypically (−0.01 to −0.29) and genetically (−0.31 to −0.53), but most significantly with body weight, capacity, size, and stature. Fat-corrected milk yield showed negligible phenotypic and low to moderately negative genetic (−0.07 to −0.29) correlations with body weight and related type traits. Total energy intake was positively related to all measures of body size, most notably body weight, while grain energy intake had moderately negative genetic correlations (−0.20 to −0.40) with the same body size traits. Because of their detrimental relationships with feed efficiency, negative selection emphasis should be placed on body weight and the related type traits capacity, size and stature. Capacity, size and stature are of moderate utility when selecting indirectly for body weight, total energy intake and feed efficiency. Key words: Dairy cattle, genetics, production, conformation, feed efficiency