Evaluation of three equine FSH superovulation protocols in mares.

The research aims to evaluate different protocols for inducing superovulation in mares, and their impact on follicular development, ovulation, and embryo recovery. It was found that pretreatment with progesterone and estradiol had no beneficial effects, and lower doses of equine follicle-stimulating hormone (eFSH) provided similar or better results in terms of embryo recovery.

Study Design and Methodology

• The study comprised two experiments wherein a total of 40 mares were assigned to four different treatment groups.
• The first group was untreated and served as a control. The other groups received different treatments involving eFSH, with some receiving pretreatment with progesterone and estradiol (P+E).
• All treated mares were subjected to 12.5mg eFSH twice daily. In two groups, the eFSH therapy was administered after a 10-day P+E pretreatment cycle.
• Prostaglandins were given on the second day of eFSH therapy, and mares were inseminated with fresh semen on the day of hCG administration and with cooled semen the next day.

Key Findings

• The study observed that, in contrast to expectation, the application of P+E before eFSH treatment resulted in lower numbers of preovulatory follicles and ovulations.
• Additionally, mares pretreated with P+E during estrus exhibited a lower embryo recovery rate per ovulation compared to other eFSH treatment groups.
• In the second experiment, two doses of eFSH (12.5 and 6.25mg) and two ovulation-inducing substances (hCG and deslorelin) were tested. A greater number of preovulatory follicles were found in mares given a higher dose (12.5mg) of eFSH. However, a higher number of ovulations occurred in mares receiving the same high dose of eFSH, followed by the administration of hCG. Comparatively, there was a higher percentage of embryos per ovulation found in mares given the lower dose of eFSH.

Conclusions

• The main findings of the research suggest that there is no clear advantage to administering P+E before eFSH treatment. Furthermore, the lower dose of eFSH resulted in fewer ovulations, but embryo recovery per flush and embryo recovery per ovulation were either similar or better than those achieved with the higher dose of eFSH.
• This suggests that lower doses of eFSH can be just as, if not more, effective in inducing superovulation and retrieving embryos.
• Thus, the study’s results may impact current practices for inducing superovulation in mares and could potentially lead to revisions in treatment protocols.