Predicting ovulation in the mare on the basis of follicular growth and serum oestrone sulphate and progesterone levels.

The research is about predicting ovulation in mares based on monitoring follicular growth and serum hormone levels. The study used 30 Finnhorse mares in the study, examining findings from 38 oestrous cycles.

Methodology

• The study was conducted using thirty Finnhorse mares, and studied 38 oestrous cycles in total.
• The mares were examined every 6 hours during the latter part of their oestrus cycle using two methods: rectal palpation and ultrasonography.
• Blood samples were also drawn daily to monitor their progesterone and oestrone sulphate levels.

Follicular Growth Observations

• The research found that in the days leading up to ovulation, the preovulatory follicle, where the egg forms, grew by average 3mm each day until two days before ovulation.
• At this point the size of the follicle remained the same until it diminished by 2-3mm during the final 12 hours leading to ovulation. The researchers observed that the maximum diameter of a follicle reached 43 +/- 4 mm.
• Interestingly, in 89% of the follicles studied, the shape became more irregular just prior to ovulation.

Hormone Level Observations

• In addition to physical examinations, the research also examined the blood hormone levels of the mares. It was discovered that the oestrone sulphate level was at its peak 24-48 hours before ovulation occurred.
• The level of oestrone sulphate started to decrease most commonly around the time from a day before to a day after ovulation. Following this trend could potentially provide an additional method to predict ovulation in mares.

Conclusion

• Overall, the researchers concluded that the most reliable method to predict ovulation in mares was to monitor the size of the follicle. This provides a direct indicator of the approaching ovulation period and is relatively straightforward compared to tracking hormonal fluctuations.