Factors affecting the efficiency of foal production in a commercial oocyte transfer program.

The research studies the efficiency of oocyte transfer (OT) in horse breeding, focusing on factors that influence successful foal production in a clinical setting. Data gathered from numerous procedures in a commercial OT program was analyzed to identify patterns, impacts of different processes, and influence of variable timings on the success of OT.

Objective of the Study

• The research aimed to understand the factors affecting the success of oocyte transfer in horse breeding. Oocyte transfer presents a useful method for producing foals from infertile mares, and through this study, the researchers sought to gain more insight into the procedure’s effectiveness in a commercial OT program.

Methods and Process

• 25 mares were enrolled for the study and 197 follicle aspiration procedures were undertaken.
• The mares were of different ages, with the average age being 23 years.
• Follicle aspiration involved placing a needle through the flank. The oocyte recovery rate per follicle aspirated was 66%.
• The researchers induced donor ovulation using deslorelin + hCG or deslorelin alone, with the former resulting in a significantly higher oocyte recovery rate (75% versus 58%).
• The age of the mare did not significantly affect the oocyte recovery rate.

Results of the Study

• Following the oocyte transfers, 42 pregnancies occurred (31%) after 14 days and 32 led to either a birth or ongoing pregnancy (23% per transfer).
• Oocytes we recovered with a compact cumulus, without donor follicle induction, or less than 20 hours after induction were linked with a reduced pregnancy rate (6%).
• Using noncycling, hormone-treated recipients also showed a significant reduction in pregnancy rate (9%).
• Unexpectedly, insemination of recipients immediately after aspirating the recipient follicle was linked with a high pregnancy rate (83%).
• The age of the mare, the induction agent used, the time gap between recipient insemination and oocyte transfer, and the time the oocyte was in culture before the transfer, did not significantly impact the pregnancy rates.

Conclusion of the Study

• The findings of the research confirm that oocyte transfer, despite variable timing of the different components involved, is effective and can be successfully implemented in a private embryo transfer practice.
• Nonetheless, some factors, such as the maturation of oocytes and hormone treatment in recipients, were observed to significantly influence pregnancy rates, necessitating their consideration in practical applications of the oocyte transfer method.