Genetic association of conformation scores with growth traits in Angus breed cattle

The objective of this work was determine the genetic association between visual scores of conformation and the traits of daily average weight gain and weight gain rate in Angus breed cattle at weaning and yearling. The components of covariance were estimated by a multitrait animal model using the Bayesian inference method, assuming a linear model for: daily average weight gain from birth to weaning (BWG) and from weaning to yearling (WYG); and weight gain rate from birth to weaning (BWR) and from weaning to yearling (WYR). A nonlinear model (threshold) was used for conformation scores at weaning (WC) and at yearling (YC). The a posteriori means for heritability were: 0.12 +/- 0.023 (WC), 0.15 +/- 0.020 (BWG), 0.15 +/- 0.024 (BWR), 0.17 +/- 0.020 (YC), 0.17 +/- 0.023 (WYG) and 0.17 +/- 0,023 (WYR). The genetic correlations ranged from -0.09 +/- 0.11 to 0.60 +/- 0.06, between WC, YC, and the daily average weight gain and weight gain rate. The correlation between WC and YC was 0.52 +/- 0.089. The direct selection for visual scores of conformation, average daily gain and weight gain rate respond slowly to selection, both at weaning and yearling.