versão impressa ISSN 1405-3195
GALLEGOS-RAMIREZ, Raymundo et al. Sire x environment interaction in the estimation of the genetic correlation between direct and maternal effects for beef cattle. Agrociencia [online]. 2011, vol.45, n.6, pp. 687-697. ISSN 1405-3195.
A precise quantification of maternal influence and genetic correlation between direct and maternal effects (rd-m) is important for the genetic evaluation of weaning weight (PD) in cattle. The aim of this study was to evaluate the effect of including sire × environment interaction (environments: herd, year, herd-year or contemporary group) on the estimation of r for PD in beef cattle. Five univariate animal models were evaluated in Angus (A, n=2985), Salers (S, n=4343) and Braunvieh (SE, n=12 320) breeds. Fixed effects in the initial model were the linear and quadratic covariates of cow age, and the linear of purebred degree in SE; the random effects were contemporary groups, direct and maternal correlated genetic effects, and permanent environment of the cow. Alternative models additionally included the sire × environmentrandom effect. Analyses were performed with the MTDFREML program and the models were compared through their AIC values. The rd-m estimates with the model without sire × environmentinteraction were: -0.09±0.34, -0.71±0.11 and -0.44±0.14 for A, S and SE. The inclusion of any interaction improved the prediction of models in the three breeds studied, accounting for 1 to 8 % of the phenotypic variance. The inclusion of sire × contemporary group in the model resulted in rd-m of less negative magnitude than with the model without the interaction (0.87± 1.21, -0.66±0.15 and -0.31 ±0.18, for A, S and SE), and generally causing better relations between the predicted direct and maternal genetic values; yet in A the could not be estimated accurately. It is advisable to include sire × contemporary group interaction in the genetic evaluation model for PD of the populations Salers and Braunvieh.
Palavras-chave : model comparison; beef cattle; weaning weight; breeding value.