The objective was to evaluate the interactions of genotype-environment effects on the components of (co)variance estimates and the prediction of breeding values for weaning weight in Nelore cattle, using a Bayesian approach. Records of 16,644 weaning weights were used from cattle distributed in ten ranches across six Brazilian states. The genetic parameters were estimated under an animal model considering Bayesian statistics. To verify genotype-environment interaction effects, we analyzed the following matrix model: without the inclusion of genotype-environment interaction effects, and with the inclusion of genotype-environment interaction effects, which considered the effect of sire-year, sire-herd, and both effects. In general, the results suggest that the inclusion of genotype-environment interaction in genetic analysis for weight at weaning tends to alter the estimates of genetic and environment (co)variances. The Spearman correlations between the breeding values were above 97%, indicating practically no change in the classification of animals evaluated. It can be inferred that the interaction effects of sire-year and sire-herd do not change the animals rank, and if not included in the genetic evaluation, the selection based on predictions of breeding values for weaning weight will not be affected.
growth; sire-year; sire-herd; genetic parameters; breeding value