Residual feed intake and gain changes the performance and carcass traits in Nellore cattle

Abstract The residual intake and gain (RIG) aims to select animals with fast growth development that present low feed intake in relation to the expected. This study aimed to evaluate the associations of selection for RIG with performance and carcass traits in Nellore cattle. Initially, residual feed intake (RFI) and residual gain (RG) were determined. From this, the RIG was calculated, and the animals were classified as efficient and inefficient for RIG. The data were subjected to analysis of variance, and the means were compared by the Tukey test at 5% probability. Pearson's correlations were estimated between performance, carcass characteristics, and RIG classes. The efficient animals for RIG showed higher daily weight gain (DWG), Longissimus muscle area (LMA), and mean metabolic body weight (MMBW)(P  0.05) were found between subcutaneous fat thickness (SFT), marbling (MAR), LMA, MMBW, and the RIG. The RIG is a measure that can be used to identify and select animals with higher rates of DWG and LMA without changes in the dry matter intake (DMI), SFT, and MAR. However, this index should still be observed with caution, as it may be dependent on body size. The selection of animals according to the RIG can be an important factor to generate phenotypic evolution in characteristics such as weight gain and rib eye area without adverse effects on the carcass fat deposition.