Parameters and genetic trends for growth traits of Nellore cattle from Bahia state using bayesian inference

Abstract

The aim of this study was to estimate genetic parameters and genetic and phenotypic trends for the weights at, 205 (P205), 365 (P365) and 550 (P550) days of age in Nellore cattle born between 1975 to 2011 from Bahia state. Data were analyzed using Bayesian uni-traits and bi-traits models with the GIBBS3F90 software. The model used for all traits included the direct and maternal genetic effects, maternal permanent environment effect, the covariate age at calving (linear and quadratic effects), plus the fixed effect of contemporary group. The heritability (direct) for the three characteristics, P205, P365 and P550 were lower than those reported in the literature, however, there is possibility of genetic gain through selection. Estimates of genetic and phenotypic trends for traits were obtained by linear regression weighted average of the dependent variable (breeding value and weights) on the year of birth. Trends estimated for P365 and P550 show that there was some genetic progress for these two traits, however, lower the weight to age 205. The observed values indicate small but favorable genetic progress for direct effect in three traits. Phenotypic progress was high in all traits, showing environmental improvement throughout the study period in Bahia state.