Integration of Interbull MACE breeding values into the multiple-trait single-step random regression test-day genetic evaluation for yield traits of Australian red breeds

Abstract

Interbull’s multiple across country evaluation provides national breeding organisations with breeding values for internationally used bulls which must be integrated into the domestic evaluation. For that purpose several methods have been proposed which either model Interbull breeding values as prior information in a Bayesian approach, or as additional pseudo data points. Single-step random regression test-day models add complexity to the integration because of the dimensionality discrepancy between the number of Interbull breeding values and the number of modelled genetic effects. This paper presents the results from integrating 16,063 Interbull breeding values into the domestic single-step random regression test-day model for milk, fat and protein yield for Australian red dairy cattle breeds. Results suggest that the integration was successful with regard to alignment of Interbull breeding values with their domestic equivalent as well as with regard to the individual and population-wide increase in reliabilities.