This study aimed to evaluate the genotype × environment interaction effect on birth (PN), weaning (P205) and yearling (P550) weights of Nellore cattle raised in 46 farms in three states (Rio Grande do Sul-RS, Santa Catarina-SC and Paraná-PR) of the South Region of Brazil, from 1976 to 2001. Records on 10,874 animals, sired by 425 bulls and 7,629 dams were used to estimate (co)variance components by REML. Univariate and bivariate models included the contemporaneous group, feeding type (P205 and P550), management type (P205 and P550), age of cow at calving (PN and P205) covariate (linear and quadratic components) as fixed effects and direct additive genetic (PN, P205 and P550), maternal (PN and P205) and residual as random effects. Direct heritability estimates of PN, P205 and P550 within each State ranged from 0.38 ± 0.04 to 0.56 ± 0.08; from 0.22 ± 0.03 to 0.47 ± 0.05 and from 0.35 ± 0,03 to 0.51 ± 0,05, respectively. Maternal heritability estimates for the States ranged from 0.19 ± 0.03 to 0.31 ± 0.03 (PN) and from 0.16 ± 0.08 to 0.48 ± 0.07 (P205). Genetic correlations for PN, P205 and P550 between states were 0.75 ± 0.03, 0.25 ± 0.05 and 0.64 ± 0.07; 0.79 ± 0.08, -0.04 ± 0.07 and 0.41 ± 0.07 and 0.53 ± 0.02, 0.08 ± 0.15 and 0.76 ± 0.09 respectively for the RS-SC, RS-PR and SC-PR pairs. Overall, the Spearman correlations between breeding values (DEP) for PN, P205 and P550 predicted in different States were low. Changes in sire ranks between states indicate the presence of genotype× environment interaction in growth traits of Nellore cattle.
beef cattle; genetic correlation; genetic evaluation; heritability; sire ranks
