The impact of direct-maternal genetic correlations on international beef cattle evaluations for Limousin weaning weight. (1st August 2021)

• Record Type: Journal Article
• Authors: Bonifazi, Renzo; Vandenplas, Jérémie; ten Napel, Jan; Veerkamp, Roel F; Calus, Mario P L
• Is Part Of: Journal of animal science. Volume 99:Number 9(2021)
• Publication Date: 2021-08-01
• Subjects: beef cattle -- direct-maternal genetic correlation -- international genetic evaluations -- interbeef -- international estimated breeding values -- weaning weight; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skab222
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: In beef cattle maternally influenced traits, estimates of direct-maternal genetic correlations ( r dm ) are usually reported to be negative. In international evaluations, r dm can differ both within countries ( r dm_WC ) and between countries ( r dm_BC ). The r dm_BC are difficult to estimate and are assumed to be zero in the current model for international beef cattle evaluations (Interbeef). Our objective was to investigate re-ranking of international estimated breeding values (IEBVs) in international beef cattle evaluations between models that either used estimated values for r dm or assumed them to be 0. Age-adjusted weaning weights and pedigree data were available for Limousin beef cattle from ten European countries. International EBVs were obtained using a multi-trait animal model with countries modeled as different traits. We compared IEBVs from a model that uses estimated r dm_BC (ranging between −0.14 and +0.14) and r dm_WC (between −0.33 and +0.40) with IEBVs obtained either from the current model that assumes r dm_BC to be 0, or from an alternative model that assumes both r dm_BC and r dm_WC to be 0. Direct and maternal IEBVs were compared across those three scenarios for different groups of animals. The ratio of population accuracies from the linear regression method was used to further investigate the impact of r dm on international evaluations, for both the whole set of animals in the evaluation and the domestic ones. Ignoring r dm_BC, i.e., replacing estimated values with 0, resulted in no (rank correlations > 0.99) or limited (between 0.98 and 0.99) re-ranking for direct and maternal IEBVs, respectively. Both r dm_BC and r dm_WC had less impact on direct IEBVs than on maternal IEBVs. Re-ranking of maternal IEBVs decreased with increasing reliability. Ignoring r dm_BC resulted in no re-ranking for sires with IEBVs that might be exchanged across countries and limited re-ranking for the top 100 sires. Using estimated r dm_BC values instead of considering them to be 0 resulted in null to limited increases in population accuracy. Ignoring both r dm_BC and r dm_WC resulted in considerable re-ranking of animals' IEBVs in all groups of animals evaluated. This study showed the limited impact of the current practice of ignoring r dm_BC in international evaluations for Limousin weaning weight, most likely because the estimated r dm_BC was close to 0. We expect that these conclusions can be extended to other traits that have reported r dm values in the range of r dm_WC values for weaning weight in Limousin.