GMACE Reliability Approximation


  • Peter G Sullivan Canadian Dairy Network


genomics, international evaluation, GMACE, reliability


Reliabilities of genomic GEBV are approximated nationally by country, and via GMACE at the international level.  In previous studies, GMACE reliabilities were sometimes lower than expected, relative to corresponding national values.  Reasons for misalignment were investigated in the present study, which revealed that two important data contributions were being ignored for the GMACE reliabilities; the effective daughter contributions (EDC) of a bull's maternal grand-sire, and the contribution of cow records for the dam.  The GMACE system was updated to properly incorporate maternal grand-sire EDC for both reliability approximation and for genomic variance estimation.  The information from cow records for the dam was added only for reliability approximation, and only if it was helpful to align approximate reliabilities, since records of the dam are otherwise excluded from the GMACE model.  These updates improved alignment of GMACE reliabilities with national values.  With only a few exceptions, GMACE reliabilities became consistently equal or higher than national values, which is the generally expected pattern of alignment.