Reproductive management of mares without detection of oestrus.

This research investigates various hormonal treatments to control and manage the reproductive cycle of mares for optimized mating times. This includes the synchronization of oestrus and the use of progestagens. After multiple sessions of controlled mating, cumulative fertility showed positive results, especially in non-lactating mares.

Research Details and Findings

• The research was conducted with primary focus on reproductive management in horses, specifically mares. The methodologies applied involve different hormone-based treatments, with an aim to synchronize the reproduction process for optimized and predetermined horse mating.
• Such synchronization objectives were targeted for an early time of the year, requiring two fundamental months of light initiated from end of November, to obtain controlled cyclicity and ovulation by the start of February.
• To simplify the treatment schedules and apply it in an efficient manner, the researchers resorted to usage of vaginal sponges for administering the treatments.

Hormone Treatments and Impact on Oestrus

• Progestagen treatments were applied in the study through the vaginal application. The onset of oestrus was successfully synchronized following the treatment applications. Typically, the response was observed around an average of 3.75 days post the withdrawal of progestagen.
• In spite of the vaginal irritations that ensued because of the treatment, a high fertility rate of 71% was observed when mares were mated every 48 hours during the induced oestrus. This confirms the effectiveness of progestagen in inducing oestrus and aiding in the fertility process.

Synchronization in Non-Conceiving Mares

• Another focus of the study was on synchronizing return to oestrus in mares that didn’t conceive in the first mating. In such cases, researchers administered oral progestagens from Day 7 to 21 after the first mating.
• Following the progesterone assay of Day 21 blood plasma, predetermined mating was decided for non-pregnant mares between Day 27 and 29, along with an hCG injection on Day 28.
• After three controlled mating periods, the cumulative fertility rate was observed at 88% for non-lactating mares and 58% for lactating ones, indicating potential effectiveness of the hormonal synchronization program in improving fertility rates.

Conclusion

• The horse reproductive management was thus achieved using the methodologies of hormonal treatments – photoperiod, progestagen, prostaglandin and hCG. The study results indicate that predetermined and controlled mating in mares is feasible, and the fertility rates can be improved considerably through hormonal synchronization.