Genetic Evaluation of Beef Sires Using a Beef-on-Dairy Crossbred Reference Population

Area of Science:

• Animal Genetics and Breeding
• Quantitative Genetics
• Livestock Production

Background:

• Beef-on-Dairy (BoD) crossbreeding aims to leverage dairy infrastructure for beef production, enhancing economic and genetic value.
• Selecting appropriate beef sires is crucial for Holstein farmers to balance high-quality beef production with minimizing calving difficulties.
• Genetic evaluation of beef sires is needed to identify bulls that improve growth while mitigating risks associated with calving.

Purpose of the Study:

• To genetically evaluate beef sires using a Beef-on-Dairy crossbred reference population.
• To assess three key economic traits: gestation length (GL), birth weight (BW), and calving ease (CE).
• To facilitate informed sire selection for dairy farmers aiming for heavier calves and reduced calving problems.

Main Methods:

• Utilized a population of 4420 BoD calves sired by Angus (ANG), Limousin (LIM), Wagyu (WAG), and White-Belgian Blue (WBB) bulls.
• Applied univariate and bivariate (linear-linear or threshold-linear) models for joint genetic evaluation using single-step methods.
• Estimated variance components and genomic breeding values, transforming calving ease (CE) estimates for interpretation.

Main Results:

• Direct heritabilities for GL, BW, and CE ranged from 0.02 to 0.37; maternal heritabilities ranged from 0.11 to 0.17.
• Male BoD calves showed higher calving difficulty, particularly with LIM sires (13%) compared to ANG (7%) and WBB (9%).
• Bivariate models improved CE prediction accuracy by 95%, with WBB sires favored over ANG for higher parity cows.

Conclusions:

• A structured BoD reference population enables accurate genomic evaluation of beef sires.
• Selection of sires can be optimized to balance economic viability with reduced calving difficulties.
• Findings support informed decision-making for dairy farmers integrating beef production.