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Title: GMACE Implementation

item SULLIVAN, P - Canadian Dairy Network
item Vanraden, Paul

Submitted to: Interbull Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2010
Publication Date: 6/1/2010
Citation: Sullivan, P.G., Van Raden, P.M. 2010. GMACE Implementation. Interbull Annual Meeting Proceedings. Interbull Bulletin 41, 5 pp.

Interpretive Summary: Programs for computing international bull rankings were updated. Genomic evaluations were included in the multi-trait across-country evaluation (GMACE) system by accounting for the additional reliability and correlations introduced when countries share genotypes and phenotypes. Methods were compared using simulated breeding values in which two groups of countries shared data within but not between regions. The new programs allow international exchange of estimated breeding values for young bulls that are genotyped but do not yet have daughter records. Selection of these bulls reduces generation interval and greatly speeds progress.

Technical Abstract: Programs to compute multi-trait across country evaluations (MACE) were adapted to include national genomic evaluations. Strategies to account for regional genotype sharing were compared using a simulated data set in which two groups of countries shared data within but not between regions. Methods worked well unless individual countries within a region report greatly differing progeny equivalents from the same shared data, but a modified covariance matrix reduces this problem. Gains in reliability were large if young bull genotypes were evaluated in each country or region; smaller gains would occur if access to genotypes is limited. Exchange of national evaluations for young bulls is becoming much more important as reliabilities of genomic evaluations increase.