The objectives of this study were to evaluate the genotype x environmental interactions and estimates of genetic parameters for weaning weight (P205) in two Brazilian regions. Weights of Nellore calves (n= 46 390) were collected over a 27 year period, on 398 farms in the regions of Pantanal and Goiás. The MTDFREML program was used for estimation of variances components. The statistical model has a fixed effect of contemporary groups (farm, sex, season and year of birth) and age of dam at parturition (quadratic); random effects of direct genetics effects, maternal genetic effects and permanent environmental effects. The genetic correlation for weaning weight in Pantanal and Goiás was 0.61, evidence of the genotype x environmental interaction. The direct and maternal heritabilities and genetic trend were 0.34, 0.07 and 8.4 kg and 0.27, 0.09 and 11.8 kg. for animals raised in Pantanal and Goiás, respectively.

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)