Genetic association between residual feed intake and carcass traits in a herd of Nellore beef cattle

Our objective was to verify if genetic differences (i.e., additive genetic variation) among animals classified in different residual feed intake adjusted for fat (RFIfat) groups occur, and if selecting for RFIfat impacts carcass traits. Ribeye area, backfat thickness, rump cap (‘picanha’ in Brazilian Portuguese) fat thickness, subcutaneous fat thickness, and marbling score were evaluated in relation to the high, medium and low RFIfat groups. Tri-trait analyses were performed using the animal model. The estimated values for heritability were high and no difference was found between the obtained values according to the RFIfat groups, for any of the carcass traits evaluated. These results demonstrate that all traits evaluated in this study have the potential for genetic improvement, regardless of RFIfat classification. The genetic improvement capacity of the herd was confirmed by the genetic trends performed using the breeding value of each RFIfat group, and independently of the group a bull belongs. Therefore, regardless of whether the animals are more or less efficient in terms of RFIfat, it is possible to practice selection for RFIfat in conjunction with carcass traits.