Ovarian function in captive feral mares.

This research focused on studying the ovarian functions in captive wild horses (feral mares) by monitoring their serum progesterone levels over a period of 33 months. It was found that these horses have seasonal cycles of ovulation mostly happening between May and October, with around 10% ovulating outside of this period in later years. The study indicated that the ovulation patterns of wild horses are not as rigid as previously thought and similar to domestic horses.

Study Design and Methodology

• The function of the ovaries in wild horses kept in captivity was monitored for a lengthy period of 33 months.
• The main method for monitoring was by checking the level of progesterone in the serum – a hormone involved in the female reproductive process.
• Progesterone levels greater than 2.0 ng/ml were considered as an indication of ovulation – the process where mature eggs are released from the ovary.

Results and Findings

• Wild horses were found to be seasonally polyestrus – a term indicating multiple ovulations within a single breeding season. Most of these ovulations were seen between May and October.
• In the first year after capture, none of the mares ovulate in the anestrous season – the period of sexual inactivity between breeding periods.
• In subsequent years, some horses (approximately 10%) began to ovulate in the non-breeding months of November, January, and February.
• Progesterone levels during the luteal phase (post-ovulation period) ranged from 2.0 to 21.0 ng/ml, similar to the levels observed in domestic mare breeds.
• The pattern of progesterone levels during pregnancy was also akin to domestic mares.

Conclusion and Implications

• The study confirmed that while the ovulation patterns in feral mares are seasonal, this seasonality is not as strict as previously believed.
• Wild horses kept in captivity behaved similarly to domestic horse breeds in the percentage of mares ovulating all year and in the progesterone levels achieved during the reproductive cycle and pregnancy.
• This research contributes valuable understanding about the reproductive processes of wild horses, which can be relevant for wild horse management and conservation strategies.