To estimate genetic parameters and to evaluate the genetic and phenotypic progress for the traits birth weight (PN), average daily gain from birth to weaning (GMDND), weaning weight adjusted to 205 days of age (P205) and the visual scores for conformation, precocity, musculature and size, at the pre weaning phase, there were used information from 23,176 Aberdeen Angus breed animals born between 1994 and 2004. The covariance components were obtained by REML, using an animal model. The direct and maternal […]

The objective of this paper was to compare the estimates of genetic parameters obtained by REML and method Â. Animal model single-trait analyses were performed using a data set of Nellore cattle. Statistical models included fixed effects of contemporary group (herd, year, sex and management groups at weaning and 550 days) and age of animal (covariable-linear effect), and additive genetic and residual random effects. Heritability estimates were 0.36 and 0.39 for weight at 550 days (W550); 0.27 and 0.29 for […]

Data on 23,251 Nelore calves weaned from 1994 to 1997, belonging to Agropecuária Jacarezinho Ltda., were analyzed to estimate the influence of environmental effects of age of dam, julian date of birth and age of calf at weaning on visual scores of conformation (C), precocity (P) and musculature (M). All effects significantly influenced the visual scores. The analyses showed that the calves with the best scores of C, P and M at weaning were those from dams with 7, 8 […]