Estimates of genetic parameters for birth and monthly weights till 450 days in Guzerá cattle

The objective of this study was to estimate genetic parameters for body weight at different ages in Guzera cattle. Birth and monthly weights till 450 days of age were analyzed with two univariate models; model 1- included additive direct and maternal genetic effects or permanent environmental effect, model 2- included additive direct and maternal genetic effects, and permanent environmental effect. Maternal heritability estimates were higher than direct heritabilities for all ages, except birth weight which showed maternal heritability zero. Models 1 and 2 produced heritabilities estimates quite similar to the direct effect. However, the maternal heritability estimates observed using model 2 were lower than the observed by model 1, and were higher than the estimates of direct effect, just for the ages 60, 120 and 210 days. In spite of the results, models 1 and 2 did not differ significantly by likelihood ratio test at 5%. The data structure, in each age month, did not allow separating direct and maternal effects appropriately.