Serial measurement of peripheral oestrogen and progesterone concentrations in oestrous mares to determine optimum mating time and diagnose ovulation.

The study explores the use of an enzyme-based immunoassay to monitor the levels of two hormones, oestradiol and progesterone, in horse breeds, with the aim of predicting the optimal time for mating and identifying ovulation. However, despite promising results, the current requirements for daily sampling and associated costs render this method impractical for now.

Methodology

• The research team used an enzyme-based immunoassay technique to measure the concentrations of two hormones associated with fertility, oestradiol-17 beta and progesterone.
• Blood samples were collected daily throughout the oestrus cycle, and for a few days after ovulation. The animals involved in the study were 34 Thoroughbred and 8 pony-type mares, including maiden, barren and foaling mares.

Findings

• In most tested mares (88%), the researchers noticed the first observable decrease in the levels of oestradiol-17 beta within the period of -72 to 0 hours relative to ovulation. In 65% of the mares, this drop was noted within the -48 to 0 hour interval.
• These findings suggest that this method could predict, with high accuracy, the correct time for a single mating and also diagnose the occurrence of ovulation in Thoroughbred mares, without the need for current management practices, such as repeated veterinary examinations of the ovaries.

Limitations

• This method requires daily blood sampling from the mares, which can be challenging and costly to implement efficiently.
• The cost associated with performing the hormonal assays also poses a significant obstacle to the practical application of the technique at this time.

Conclusion

• While the enzyme-based immunoassay method has been found useful in predicting optimal mating times and diagnosing ovulation in mares, the need for daily blood sampling and the cost of hormone assays are significant impediments to its practical application.
• Further research and development are required to streamline this process or find more cost-effective methods to achieve the same results.