Induction of multiple ovulations during the ovulatory season in mares.

This research assesses the use of an equine pituitary extract to stimulate multiple ovulations in mares during their ovulation season. Different parameters, such as timing and dose, were experimented with to optimize results.

Overview of the Study

• The study involved conducting four experiments on a total of 112 horse mares. The primary aim was to determine the effectiveness of an equine pituitary extract for stimulating multiple ovulations during the ovulatory season.
• In the combined results from all experiments, it was found that 70% of the mares (78 out of 112) exhibited multiple ovulations, with an average of 3.0 ovulations per mare.

Role of Human Chorionic Gonadotropin (hCG)

• The interval between the first and last ovulation was seen to decrease significantly when human chorionic gonadotropin (hCG) was part of the treatment regimen.

Timing of Treatment Initiation

• The timing of initiating the extract treatment also influenced the ovulation rate. When treatment was started on day 19 post-ovulation, the ovulation rate was lower as compared to initiation on day 15 post-ovulation.
• Starting the treatment on day 11 post-ovulation produced the same effect as when it was commenced on day 15, regardless of whether an injection of prostaglandin F(2alpha) was administered on the first day of extraction treatment.

Dosage of Extract

• The dosage of the extract in the treatment also underwent testing. Whether the dose was increased from 750 to 1500 or 2250 units per day, there was no significant increase in the ovulatory response, suggesting that higher doses do not necessarily lead to a better ovulatory response.

Conclusion

• In conclusion, the study demonstrated the effectiveness of the equine pituitary extract in inducing multiple ovulations in mares. It also answered several questions related to optimizing the use of the extract, such as the involvement of hCG, the right timing for initiating the treatment, and the suitable dosage.