Outstanding Gir oocyte donors: How does individual factor affect in vitro embryo production efficiency?

Area of Science:

• Reproductive Biology
• Animal Science
• Embryology

Background:

• Oocyte donor variability is a critical factor influencing success rates in bovine in vitro embryo production (IVP).
• Identifying high-performing animals is essential for optimizing IVP efficiency and reproductive outcomes in cattle.

Purpose of the Study:

• To quantify the impact of individual oocyte donor performance on IVP efficiency within a Gir cattle population.
• To assess the relationship between donor efficiency, measured by blastocyst/oocyte ratio, and key IVP metrics.

Main Methods:

• Analysis of 1,734 observations from 250 Gir oocyte donors, categorized into high (>0.48), average (0.17-0.48), and low (<0.17) efficiency groups based on blastocyst/oocyte ratio.
• Comparison of cumulus-oocyte complex indicators and embryo production rates (blastocysts per OPU, pregnancies per OPU) across donor efficiency groups.

Main Results:

• High efficiency donors exhibited lower cumulus-oocyte complex indicators (total number, IVF-grade number, IVF-grade/total ratio) compared to average and low efficiency groups (p < 0.05).
• Blastocyst production per OPU was significantly higher in high efficiency donors and lower in low efficiency donors versus the average group (p < 0.05).
• Pregnancy rates per OPU were 4.3-fold higher in high efficiency donors compared to low efficiency donors (p = 0.017).

Conclusions:

• Donor selection based on high blastocyst/oocyte ratio is a crucial strategy for enhancing blastocyst and pregnancy yields in bovine IVP.
• Utilizing high-efficiency donors significantly improves the overall success and economic viability of IVP programs in cattle breeding.