Efficiency of superovulation and in vivo embryo production in eFSH-treated donor mares after estrus synchronization with progesterone and estradiol-17beta.

The research investigates the efficiency of a hormonal treatment regimen on superovulation and embryo production in female horses. Contrary to expectations, the regimen didn’t significantly enhance embryo recovery rate and even led to a lower embryo per ovulation rate.

Objective and Methodology

• The aim of the study was to evaluate the effectiveness of the combination of progesterone and estradiol-17beta (P&E) hormones in regulating estrus cycles and inducing superovulations in mares.
• The researchers also investigated if the addition of equine follicle-stimulating hormone (eFSH) would boost folliculogenesis and increase embryo production.
• The mares were administered daily with P&E for 10 days. On the final day, prostaglandin F2alpha was given to the mares to prompt luteolysis, the degradation of the corpus luteum.
• The horses were then divided into two groups. In the eFSH group, the mares were subjected to eFSH treatments twice daily once their follicle size reached 20 to 25 mm. This treatment was stopped when the follicle reached a size of 35 mm or larger.
• The second group was the control group, where mares were monitored but received no eFSH treatment. Once the follicles reached the size of 35 mm or larger, human chorionic gonadotrophin (hCG) was administered to both groups after 36 hours.

Findings and Conclusion

• All mares were inseminated with fresh semen and embryo recovery attempts were carried out 8 days post ovulation. However, the results showed that the synchrony of ovulations within each group was similar.
• Despite inducing a higher number of pre-ovulatory follicles and ovulations, the eFSH treatment failed to increase the embryo recovery rate and resulted in a lower embryo per ovulation rate.
• Additionally, a significant number of mares in the eFSH treated group failed to ovulate and had an elevated number of non-ovulatory follicles and increased periovulatory estradiol-17beta concentrations in comparison to the control group.
• Based on these findings, the researchers concluded that the combined treatment of P&E with eFSH cannot be recommended for cycling donor mares due to its inefficient results and unfavourable effects.