Genetic parameters for linear type traits in Czech Holstein cattle

The objectives of this study were to estimate genetic parameters for 18 currently recorded linear conformation traits in Czech Holstein cattle. The data set consisted of 78 886 first-lactating Holstein cows. Traits, all scored on a 9-point scale, were fore udder attachment, rear udder height, udder depth, rear udder width, central ligament, teat length, front teat placement, rear teat position, stature, angularity, chest width, body depth, rump angle, rump width, rear legs rear view, rear leg set (side view), foot angle, and bone quality. Uni- and bivariate animal models were used. The models included fixed effects of herd-date of classification-classifier, classifier, and season of calving, quadratic regressions on age at calving and on days in milk and the random effect of animal. Heritability estimates obtained in univariate and in bivariate analyses were of similar magnitude. Heritabilities ranged from 0.17 to 0.32 for udder traits, 0.10 to 0.16 for foot and leg traits, and 0.18 to 0.45 for traits related to body size. Genetic correlations among the currently recorded linear traits ranged from -0.67 between foot angle and rear leg set (side view) to 0.75 between fore udder attachment and udder depth. Substantial genetic correlations were found for the following pairs of traits: rear udder height and rear udder width (0.70), chest width and body depth (0.69), front teat placement and rear teat position (0.68), angularity and bone quality (0.67). Corresponding phenotypic correlations for most pairs of traits were similar in direction but smaller in magnitude than the genetic correlations.