Accounting for backfat thickness on the prediction of residual feed intake of young beef bulls influences its relationship to breeding soundness examination traits

An abstract of a study by Antillon-Ruiz et al examining the relationship between two alternative residual feed intake (RFI) measures and breeding soundness examination traits in Angus young bulls is presented. Animals were classified into those with the greatest (least efficient, n = 8), intermediate (n = 9), and least (most efficient, n = 8) RFI values. Two separate one-way ANOVA were performed to evaluate the class effects of feed efficiency as determined by RFIKoch or RFIfat. For significant ANOVA results, a Tukey's range test was run for means comparisons of efficiency groups. Under the RFIKoch classification, SPC and NSF tended to be greater (P = 0.10) for the least efficient group (418.2 ± 97.9 millions/ml and 89.6 ± 3.0%) than for the intermediate (146.2 ± 92.3 millions/ml and 80 ± 2.8%) and most efficient (245.8 ± 97.9 millions/ml and 83.2 ± 3.0%) groups. Those differences disappeared when accounting for BFT under the RFIfat classification.