Data selection and pilot run on simplified genomic MACE (S-GMACE)

Abstract

As a first step to international evaluation of genomically enhanced breeding values (GEBV) a pilot run on Simplified Genomic Multiple Across Country Evaluation (S-GMACE) was performed. This implies that only one GEBV per bull is considered in the analysis. GEBV data for Holstein bulls corresponding to the December 2010 routine MACE run from 3 to 7 countries for the traits protein yield, somatic cell score, stature, direct longevity and cow conception 1 (measures as conception rate) were available. For bulls with several GEBVs only one was chosen based on the following hierarchical selection criteria: largest number of daughters, country of first registration, highest correlation to country of first registration, and highest genomic reliability. The GEBV data were merged with the corresponding pre-edited conventional EBVs. In cases where both a GEBV and an EBV for the same bull existed within a country the EBV was discarded. The final dataset ranged from 68,481 (cow conception 1) to 151,904 records (protein yield) with a GEBV proportion from 40% (protein yield) to 52% (cow conception 1). The data were analyzed with MACE methodology using sire-dam relationships. Genetic trends of conventional and genomic runs coincided. Young bulls were among the top 100. In the case of protein yield they ranged from 26 to 64 according to the country scale. Due to the inclusion of genomic information there was an overall increase in international reliability on all country scales. Harmonization of input data is important in order to fairly select among GEBVs from different sources.