Genomic prediction ability and genetic parameters for residual feed intake calculated using different approaches and their associations with growth, reproductive, and carcass traits in Nellore cattle.

This study aimed to estimate prediction ability and genetic parameters for residual feed intake (RFI) calculated using a regression equation for each test (RFI _test ) and for the whole population (RFI _pop ) in Nellore beef cattle. It also aimed to evaluate the correlations between RFI _pop and RFI _test with growth, reproductive, and carcass traits. Genotypic and phenotypic records from 8354 animals were used. An analysis of variance (ANOVA) was performed to verify the adequacy of the regression equations applied to estimate the RFI _test and RFI _pop . The (co)variance components were obtained using the single-step genomic best linear unbiased prediction under single and two-trait animal model analyses. The genetic and phenotypic correlations between RFI _test and RFI _pop with dry matter intake, frame, growth, reproduction, and carcass-related traits were evaluated. The prediction ability and bias were estimated to compare the RFI _test and RFI _pop genomic breeding values (GEBV). The RFI _pop ANOVA showed a higher significance level (p < 0.0001) than did the RFI _test for the fixed effects. The RFI _pop displayed higher additive genetic variance estimated than the RFI _test , although the RFI _pop and RFI _test displayed similar heritabilities. Overall, the RFI _test showed higher residual correlations with growth, reproductive, and carcass traits, while the RFI _pop displayed higher genetic correlations with such traits. The GEBV for the RFI _test was slightly biased than GEBV RFI _pop . The approach to calculate the RFI influenced the decomposition and estimation of variance components and genomic prediction for RFI. The application of RFI _pop would be more appropriate for genetic evaluation purpose to adjust or correct for non-genetic effects and to decrease the prediction bias for RFI.
(© 2022. The Author(s), under exclusive licence to Institute of Plant Genetics Polish Academy of Sciences.)