Comparison of national genomic predictions of EuroGenomics exchanged young bulls

Abstract

Since the formation of EuroGenomics Consortium in 2009, member countries exchange routinely genotypes of reference bulls for Holstein breed. By April 2013, a total of 25,903 Holstein bulls were included in EuroGenomics common bull reference population. It was of interest to investigate consistency of national genomic predictions based on the same reference population. The objective of this study was to compare national genomic predictions of the EuroGenomics member countries using common young bulls. Genotypes of all male candidates, culled or selected, born in 2010 (N=12,336) were exchanged between Germany (DEU), Nordic countries (DFS), France (FRA), and The Netherlands (NLD). National genomic breeding values and their associated reliabilities were provided by the four countries for four selected traits: protein yield, udder depth, somatic cell scores, and cow’s ability to conceive. For protein yield, GEBV correlations between any two country scales reached 0.90. Similar levels of GEBV correlations were found also for udder depth and somatic cell scores. The fertility trait with lowest heritability had somewhat lower GEBV correlations between country scales. It can be clearly seen that foreign bulls had equal variance in GEBV as domestic ones. Around two thirds of top 500/1000 bulls were common for protein between DEU, DFS or NLD scales. The highly correlated national GEBV of the exchanged young bulls can be attributed to the high genetic correlations between the countries and the sharing of the common bull reference population and using the same pedigree und similar phenotypes for national genomic predictions in the EuroGenomics countries. Foreign bulls were no longer disadvantaged in ranking, compared to domestic bulls. The highly consistent national GEBV of the EuroGenomics countries confirmed a high quality of the EuroGenomics genomic predictions and increased the trust of breeders in the EuroGenomics genomic evaluations.