Integration of MACE breeding values into the Single-Step genetic evaluation for conformation in Brown Swiss

The German-Austrian official genomic evaluation for conformation traits in Brown Swiss has used information from foreign bulls since its introduction in 2011. Access to genotypes of foreign bulls has been possible through the participation in the InterGenomics consortium. Initially, genotypes and de-regressed MACE breeding values of foreign bulls were integrated in a calibration set of a two-step genomic evaluation system. In April 2021, the first official genomic breeding values for conformation traits from a single-step system including foreign information were published. The objective of this work is to present an overview of the method and the effects of the inclusion of foreign information in the new single-step system. Data from the December 2020 run of the German-Austrian official genomic evaluation for 29 conformation traits in Brown Swiss were used. Benefits from the inclusion of external MACE information were assessed in a "minus 4 years" validation framework and quantified in terms of validation reliability. For that, data was truncated to the status of December 2016 and evaluations were conducted with and without external MACE breeding values. The truncated dataset included 23 992 genotyped animals, from which 5 757 originated from the exchange with InterGenomics partners. External MACE breeding values were corrected to remove information on domestic daughters and then de-regressed. Final observations used in the analyses comprised yield deviations of domestic cows and de-regressed corrected MACE breeding values as pseudo-phenotype of bulls with additional foreign information. The number of foreign bulls contributing a phenotype to the evaluations ranged from 2 968 to 6 607, with an average of 5 270. Validation reliabilities with the inclusion of external MACE breeding values increased by on average 6 reliability percentage points. The gains ranged from 2 to 13 depending on the trait. In udder score, for example, the validation reliability increased from 0.40 to 0.45. In conclusion, integration of foreign information in the new single-step system resulted in notable increase in validation reliabilities.