Abstract

GONCALVES, F.M et al. Genetic evaluation for body weight in a Nellore herd. Arq. Bras. Med. Vet. Zootec. [online]. 2011, vol.63, n.1, pp. 158-164. ISSN 0102-0935.  http://dx.doi.org/10.1590/S0102-09352011000100024.

The heritabilities for direct and maternal genetic effects and genetic correlations between these effects were estimated for weight at 205 (P205), 365 (P365), and 550 days (P550) in a Nelore herd in northern Minas Gerais. The statistical model included direct and maternal additive effects, in addition to the fixed effects of contemporary group (farm, gender, diet, season - dry and water -, and year of birth) and the covariate age of cow at calving (linear and quadratic effects). The variance components and genetic values were estimated by REML method. The genetic trend was obtained using the regression of the annual mean genetic value in relation to the year birth. The heritability estimates for the direct additive effect () for P205, P365, and P550 were equal to 0.60, 0.69, and 0.75, respectively. These coefficients showed high magnitude, indicating that the herd in question presents a great additive genetic variability and therefore it is expected a great progress using genetic selection. By the analysis of genetic trend, it was verified a development in animals genetic values over the years studied.

Keywords : genetic trend; heritability; beef cattle; REML.