The objective of this study was to measure the genotype-environment interaction (GEI) effect on some growth traits in Nellore cattle. Data from 2,896 records of pre-weaning (PW), 2,605 of weaning (WW) and 1,522 of post-yearling (YW) weights with a total of 9,911 pedigree animals from two farms of different regions of Minas Gerais State, South (farm I) and Northeast (farm II) were analyzed. Contemporary groups consider the effects of month-year of birth, sex, and herd. Only data from animals raised under pasture conditions were used. Covariance components were estimated by MTDFREML. Direct heritability obtained from bivariate analyses were 0.24, 0.16 and 0.17 (farm I) and 0.25, 0.24 and 0.17 (farm II) for PW, WW and YW, respectively. The ranking correlations between farms were 0.74, 0.76 and 0.51 and genetic correlations between farms were 0.96, 0.95 and 0.53 for PW, WW and YW, respectively. These results showed that there was no evidence of GEI up to weaning time but there was a significant effect of this interaction on the post-yearling weight. If selection criterion includes growth traits measured after weaning, regional evaluation should be recommended for bulls choice.
Beef cattle; Nellore; genotype-environment interaction
