Associação genética da prenhez aos 16 meses com o peso à desmama e o ganho de peso em animais da raça Nelore

Abstract

The objective of the present study was to determine the possible use of heifer pregnancy at 16 months (HP16) as a selection criterion and its possible genetic associations with weaning weight (WW) and average daily gain from weaning to yearling (ADGWY). Covariance components were estimated by uni and bivariate animal models assuming a linear model for weaning weight and average daily gain from weaning to yearling and a nonlinear for HP16. Variance components and breeding values were estimated using Bayesian inference. Flat distributions were used for all (co)variance components and genetic correlations. The estimates of heritability direct for HP16, WW and ADGWY were 0.50; 0.24 and 0.15; respectively. And the maternal heritability estimate for the WW was 0.07; The genetic correlations were -0.25 and 0.09; between HP16, WW and ADGWY, respectively; and the genetic correlation between HP16 and maternal effects of WW was 0.29. The heritability estimate of heifer pregnancy at 16 months indicated that the trait can be used as a selection criterion. The genetic correlation estimates indicated that the selection for heavier animals at weaning, in the long-term, could decrease the occurrence of heifer pregnancy at 16 months. Moreover, the selection for animals with greater maternal ability can favor the selection for precocious animals. However, the selection for average daily gain from weaning to yearling will not cause genetic change in female sexual precocity. © 2009 Sociedade Brasileira de Zootecnia.