Resumo

RIBEIRO, Maria Norma et al. Heritability of maternal and direct effects of growth traits in Nellore herds at Paraiba State, Brazil. Rev. Bras. Zootec. [online]. 2001, vol.30, n.4, pp. 1224-1227. ISSN 1806-9290.  http://dx.doi.org/10.1590/S1516-35982001000500014.

Weight records at 205 (205W), 365 (365W) and 550 (550W) days of age of three Nellore herds raised in Paraíba State from 1975 to 1990, were used in the analyses. Genetic and maternal effects were estimated with the restricted maximum likelihood method, assuming an animal model. There were included the fixed effects of year-month-sex and farm. The linear and quadratic effects of age of dam at calving were included in the model as covariables. The least squares means and respective standard errors for P205, P365 and P550 for three studied farms were, respectively, 149.00 ± 22.28 kg, 198.40 ± 38.84 kg, 256.99 ± 55.65 kg; 145.10 ± 21.31 kg, 182.83 ± 30.38 kg, 247.45 ± 50.57 kg e 162.12 ± 14.23 kg, 246.66 ± 23.11 kg, 332.83 ± 35.02 kg. The heritabilities estimates for genetic direct effect were 0,16 ± 0,05, 0,40 ± 0,11 e 0,76 ± 0,25, for 205W, 365W and 550W, respectively. The heritabilities estimated for the maternal effects of 205W, 365W and 550W were 0,36 ± 0,05, 0,44 ± 0,15 and 0,01 ± 1,10, respectively. The correlations between direct and maternal effect for 205W, 365W and 550W were -0,70, -0,74, and -1,00, respectively. Maternal effects were important only in the pre-weaning phase.

Palavras-chave : growth; genetic parameters; Nellore cattle.