Detection of evaluation bias caused by genomic preselection

Area of Science:

• Animal genetics
• Quantitative genetics
• Biometrika

Background:

• Genomic preselection of bull calves introduces bias in international genetic evaluations.
• Current multi-step genomic breeding value calculations can be inaccurate.
• Heterogeneous data in international evaluations necessitates robust validation methods.

Purpose of the Study:

• To investigate the impact of genomic preselection on Mendelian sampling (MS) means and variances.
• To assess the detectability of genomic preselection bias using the MS validation test.
• To evaluate the consequences of genomic preselection on breeding value estimation.

Main Methods:

• Simulation study with 50 replicates under control and genomic preselection schemes.
• Utilized real data structures and pedigree from a medium-size cow population.
• Incorporated a genetic trend and analyzed data with heritabilities of 0.25 and 0.10.

Main Results:

• Genomic preselection led to underestimation of bulls' breeding values (BV).
• Significant deviations from zero were observed in true and estimated MS means.
• Bias in estimated BV and MS means/variances increased with lower trait heritability.

Conclusions:

• The MS validation test can detect genomic preselection bias.
• Genomic preselection significantly impacts breeding value accuracy and genetic variance estimation.
• Accounting for genomic preselection is crucial for accurate international genetic evaluations, especially for low heritability traits.