Genetic parameters estimation among pre and post weaning weights in nellore breed

Abstract

Correlations among two or more traits indicate the extent to which they are associated. The level and magnitude of this association are key factors in genetic improvement because the goal is to enhance the genetic makeup of a group of traits that act simultaneously. Therefore, the aim of this study was to estimate the components of variance and heritability for standard weights at 120, 240, 365, 450 and 550 days of age (P120, P240, P365, P450 and P550, respectively), and the genetic correlation among P120 and other weights in Nellore cattle using a database of 29 769 records. Bivariate analysis was carried out for all the traits using P120 as an anchor, and additive covariance was fixed as an analytical strategy in order to obtain genetic correlation estimates. Heritability (h2) values were 0.21 for P240; 0.37 for P365; 0.36 for P450 and 0.42 for P550. The estimation of h2 varied between 0.23 and 0.31 for W120. Genetic correlation estimates were high and positive, 0.96, 0.87, 0.79 and 0.76 among P120 and P240, P365, P450 and P550, respectively. These values indicate that selection for weight at younger ages will lead to a corresponding change in later weight, in the same direction.