International single-step SNPBLUP beef cattle evaluations for Limousin weaning weight

Area of Science:

• Animal Breeding and Genetics
• Quantitative Genetics
• Genomic Evaluation

Background:

• International collaboration enhances accuracy of estimated breeding values (EBVs) through larger reference populations.
• Genomic selection is growing in beef cattle, but its international application benefits remain underexplored.
• Developing international single-step genomic evaluations is crucial for optimizing genetic gain.

Purpose of the Study:

• To develop an international single-step genomic evaluation for beef cattle.
• To assess the impact of international genomic evaluations on EBV accuracy and bias compared to national and international pedigree-based methods.

Main Methods:

• Utilized weaning weight records from 331,593 animals across seven European countries.
• Implemented international single-step SNPBLUP (ssSNPBLUP_INT) and pedigree-based BLUP (PBLUP_INT) evaluations, alongside national scenarios.
• Estimated EBV accuracy, bias, and population accuracy increases using linear regression.

Main Results:

• International single-step SNPBLUP (ssSNPBLUP_INT) demonstrated superior EBV accuracies.
• ssSNPBLUP_INT increased population accuracy by 13.7% for direct and 25.8% for maternal EBVs compared to PBLUP_INT.
• Observed accuracy improvements across all countries when transitioning from national to ssSNPBLUP_INT, with similar or reduced bias.

Conclusions:

• International single-step SNPBLUP evaluations are feasible and enhance population accuracies for beef cattle.
• Larger multi-country reference populations and inclusion of international relatives improve evaluation outcomes.
• The proposed international single-step approach is applicable to other traits and breeds.