Effects of embryo transfer in beef cattle on genetic evaluation methodology

Area of Science:

• Animal breeding and genetics
• Reproductive technologies in livestock

Background:

• Superovulation and embryo dispersal in cattle necessitate adjustments to genetic evaluation systems.
• Current genetic models may not adequately account for the influence of surrogate dams on offspring traits.

Purpose of the Study:

• To propose modifications to recording systems and genetic evaluation models for cattle utilizing surrogate dams.
• To address the impact of surrogate dam characteristics on genetic evaluations, particularly for maternal traits.

Main Methods:

• Discussed the need for enhanced recording systems to capture surrogate dam breed, age, and registration details.
• Outlined the necessity for genetic models to distinguish between natural and surrogate dams.
• Presented a simplified mixed model equation example for genetic evaluations when only surrogate dam breed is known and progeny is singular.

Main Results:

• Identified key data requirements for recording systems, including surrogate dam breed and age.
• Highlighted the importance of differentiating maternal effects from natural versus surrogate dams in genetic models.
• Demonstrated a simplified approach to mixed model equations under specific assumptions regarding surrogate dams.

Conclusions:

• Modifications to recording systems and genetic evaluation models are essential for cattle breeding programs employing superovulation and surrogate dams.
• Further research is needed to explore interactions between surrogate dam breed/age and calf sex.
• Simplified genetic evaluation models are feasible when specific information about surrogate dams is available.