Control of ovulation in mares in the early breeding season with ovarian steroids and prostaglandin.

The research article is about the examination of two trials conducted to assess the efficiency of combined treatments of progesterone, estradiol-17 beta, and prostaglandin in controlling the ovulation of mares in the early breeding season.

Experiment Design and Methodology

• The experiment was designed to conduct two separate trials with the aim of:
  • Determining the effectiveness of treating mares with progesterone and estradiol-17 beta after exposing them to an artificial increased photoperiod.
  • Examining how such a procedure could be integrated into equine breeding farm management systems.
• The mares in the trials received a 15-day treatment of 150 mg progesterone and 10 mg estradiol-17 beta each day.
• On the last day of the steroid treatment, the mares received 10 mg of PGF-2 alpha.

Results and Findings

• In the first trial, 27 out of 31 mares ovulated between the 8th-14th days after the last injection.
• When mated during that period, the conception rate of the mares was 77%, compared to a 50% conception rate for untreated mares who mated at their first heat cycle following the treatment period.
• A second, larger trial involving the same treatment for a 10-day period was performed, resulting in ovulation for 103 out of 128 mares between the 9th-16th days after the last injection.
• Of these mares, 62% of who were mated during that period were able to conceive.

Conclusions

• The combined steroid treatment resulted in reasonably precise and practical control of ovulation in mares adequately stimulated by an increased photoperiod.
• The treatment did not appear to have a negative effect on the mares’ fertility, as the conception rate was higher for mares who underwent the treatment and mated during the specified period.
• These findings suggest that this treatment could be a viable option for equine breeding farms looking to have more control over mares’ ovulation cycles.