Abnormal reproductive patterns in Przewalski’s mares are associated with a loss in gene diversity.

The research is an investigation of the reproductive patterns of the Przewalski’s horse and how it is influenced by age and gene diversity. The main finding reveals that decreased gene diversity is linked to abnormal reproductive patterns in these horses, hence suggesting the need for long-term genetic management to maintain reproductive fitness.

Research Context and Objective

• This research focuses on the Przewalski’s horse, a endangered species, with an alarming demographic tilt towards older individuals and a low foaling rate, resulting in the population not being self-sustaining.
• The main objective of the research was to explore the reproductive biology of this species, specifically assessing the influence of age and gene diversity on their reproductive function.

Research Methodology

• This research included a detailed study involving 19 mares, where urine samples were gathered multiple times per week over a period of five months.
• Extensive ultrasound exams were also performed on nine of these mares, conducted three days a week for five weeks. This allowed the researchers to evaluate the follicular structures, which are crucial in reproductive health.

Key Findings

• The researchers discovered abnormal or acyclic reproductive patterns in a significant number of these mares.
• They established that the average estrous cycle length in cyclic mares was a little over 25 days with around 12 days of diestrus.
• The growth rate of follicles in these mares during a cycle was found to be around 1.2 mm per day, and ovulation typically occurred once they reached a size of approximately 40.4 mm.
• It was observed that mares with a high inbreeding coefficient had lower levels of urinary estrogens, which are vital to normal reproductive function.
• In this population, age did not significantly affect the reproductive patterns.
• The overall data suggests a correlation between reduction in gene diversity and abnormal reproductive patterns. As such, long-term genetic management appears necessary to maintain reproductive fitness within the population of this species.