Avoiding Bias From Genomic Pre-Selection in Converting Daughter Information Across Countries


  • Paul M VanRaden USDA Animal Improvement Programs Lab


single-step genomic evaluation, foreign data, selection bias


Methods to include both foreign and genomic information in single-step or multi-step evaluations were developed and compared using the U.S. national Jersey database. Breeders have exchanged and converted genetic evaluations of bulls across countries for decades, but traditional evaluations may become biased by pre-selection on genotype. When foreign and genomic data were added to the equations, daughter yield deviations computed from only domestic daughter records were very stable. Those could be exchanged internationally, thereby avoiding the difficulty of deregressing genomic evaluations. A final step in the multi-step method simply inserted the genomic evaluations and held them constant during iteration instead of adjusting the data vector and equations. For genotyped young bulls, multi-step evaluations were correlated by .966 to single-step evaluations computed with an algorithm that did not require inverting the genomic relationship matrix. Accuracy was similar but regressions were closer to expectation for the single-step evaluations.

Author Biography

Paul M VanRaden, USDA Animal Improvement Programs Lab

Research geneticist