Beef cattle

Genomic evaluation of residual feed intake adjusted for rump fat in beef cattle: implications for selection strategies

---

Abstract

Feed costs can account for up to 75% of total production expenses; therefore, improving feed efficiency is a key driver of profitability in beef cattle systems. Residual feed intake (RFI) is widely used to select animals for feed efficiency. However, previous studies reported that more efficient animals tend to have leaner carcasses. To ensure that RFI differences are not confounded with carcass fat variations, adjusting RFI for fat related traits, such as rump fat thickness (RFT), can be a valuable approach, since is an economically important trait that reflects carcass quality, energy requirements, and reproductive maturity in females. In this study we aimed to: 1) to estimate variance components and genetic correlations between RFI-calculated with (RFIF) and without (RFIW) adjustment for RFT using genomic data in Nellore cattle, and 2) to assess the accuracy, bias, and dispersion of genomic breeding values for RFIF and RFIW predicted via single-step genomic BLUP (ssGBLUP) using Linear Regression. We hypothesized that accounting for RFT would explain a small portion of RFI variation, with minimal impact on selection outcomes. Phenotypic records were obtained from 9,094 Nellore cattle (3,253 females and 5,952 males) across 14 feed efficiency tests conducted between 2011 and 2024. The pedigree comprised 17,407 animals, with 5,812 of them being genotyped. Linear and threshold animal models were applied for continuous and categorical traits, respectively. Heritability estimates were low for RFIF (0.16 ± 0.02) and RFIW (0.17 ± 0.02), and the genetic correlation between them was high (r = 0.98 ± 0.03). RFI showed a low correlation with RFT (r = 0.15 ± 0.08), indicating limited overlap between feed efficiency and fat deposition. Spearman correlations between RFIF and RFIW genomic breeding values were 0.98 ± 0.00 in females and 0.95 ± 0.00 in males. Genetic correlations of RFIW and RFIF with growth, reproductive, and carcass traits ranged from -0.33 (HPD: -0.83; 0.15) to 0.35 ± 0.11, suggesting selection for RFI is unlikely to compromise these traits. Prediction accuracy was similar for RFIF (0.43) and RFIW (0.44), and differences in bias (-0.003 and -0.0003) and dispersion (0.95 and 0.97) were minor. Although RFIF captured slightly more genetic variability, the difference was minimal, and the strong linear relationship with RFIW indicates that adjusting for RFT provides little additional information, especially in females. These results suggest that RFI adjustment for RFT may not be necessary for selection. Nonetheless, considering the complete set of performance traits remains essential to optimize genetic progress and avoid unintended consequences. Our findings provide valuable insights for genomic selection strategies in Nellore cattle, highlighting that feed efficiency can be effectively selected without adjustments for rump fat, thereby simplifying breeding decisions while maintaining balanced improvement across economically important traits.

Keywords: 2026

How to Cite:

Temp, L., Pereira, L., Bussiman, F., Hidalgo, J., Lourenco, D. & Baldi, F., (2026) “Genomic evaluation of residual feed intake adjusted for rump fat in beef cattle: implications for selection strategies”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2257521. doi: https://doi.org/10.31274/wcgalp.23389

Rights: 1