Genetic parameters and selection responses for feed efficiency, growth, and carcass traits in performance-tested Nellore cattle

Abstract Improving feed efficiency is a key strategy for increasing the biological and economic sustainability of beef cattle production systems. This study aimed to estimate genetic parameters and characterize additive genetic associations and expected correlated responses among feed intake, growth, and carcass traits in performance-tested Nellore cattle. Phenotypic records from 1,394 Nellore males evaluated in 14 performance tests conducted by the Embrapa Geneplus breeding program between 2016 and 2024 were analyzed, together with pedigree information comprising 7,168 animals. The evaluated traits were dry matter intake (DMI), body weight (BW), average daily gain (ADG), residual feed intake (RFI), ribeye area (REA), and subcutaneous fat thickness (SFT). Genetic parameters were estimated using a Bayesian six-trait animal model, including performance test as a fixed effect, age at the beginning of the test as a linear covariate, and additive genetic animal effect as a random effect. Posterior mean heritability estimates were 0.373 ± 0.076 for DMI, 0.744 ± 0.070 for BW, 0.213 ± 0.066 for ADG, 0.277 ± 0.078 for RFI, 0.630 ± 0.087 for REA, and 0.402 ± 0.090 for SFT, indicating exploitable additive genetic variation for all evaluated traits. Residual feed intake showed a moderate positive additive genetic correlation with DMI (0.58) and ADG (0.42), whereas its associations with BW (− 0.17), REA (− 0.27), and SFT (− 0.11) were low to moderate and negative. Ranking based on estimated breeding values showed similar patterns, with Spearman correlations of 0.33, 0.65, − 0.28, − 0.29, and − 0.21 between RFI and DMI, ADG, BW, REA, and SFT, respectively. The comparison between extreme RFI breeding-value groups demonstrated that genetically more efficient animals (lowest RFI decile) exhibited lower genetic propensity for DMI (− 0.41) and ADG (− 0.65), but greater genetic merit for BW (+ 0.80) and REA (+ 0.71) compared with genetically less efficient animals. These results demonstrate that RFI represents an exploitable source of additive genetic variation for improving feed efficiency in Nellore cattle. However, the antagonistic association with growth rate highlights the importance of multi-trait selection strategies integrating feed efficiency, growth, and carcass attributes to achieve balanced genetic progress.