GMACE without variance estimation

Abstract

Genomic variances have been estimated and used in GMACE since 2011, to adjust for differences among countries in the scaling of young bull genomic evaluations relative to progeny-tested bulls.  Interbull has implemented validation tests for national genomic evaluations, which countries must pass in order to participate in GMACE, and the sharing of data and knowledge among countries for genomic evaluations has also increased.  Each of these factors can improve consistency of genomic results among countries, and may reduce the need for genomic variance adjustments in GMACE.  Cross-validation tests have been used previously to compare GMACE results when using versus not using genomic variance adjustments, and have shown clear advantages for including genomic variance adjustments.  When repeated on current data for the present study, however, the cross-validation results no longer showed this clear advantage.  Genomic variance adjustments were helpful for some traits and countries but not for others.  On balance across all traits and countries, there was no longer a clear advantage either way.  The international sharing of data and knowledge, combined with genomic validation tests of Interbull are likely helping to reduce differences among countries in the relative scaling of genomic versus progeny-test evaluations within the same country.