Asynchronous ovulation in mares: seasonal variations in frequency.

The research article investigates the incidence of synchronous and asynchronous double ovulation in mares, and how it varies across different seasons. The researchers conclude that asynchronous double ovulation is common, especially during the seasonal transition periods, and emphasize the importance of closely monitoring mares to avoid missing signs of multiple pregnancy.

Objective of the Research

• The main goal of the study was to document the rate of synchronous (occurring at the same time) and asynchronous (occurring at different intervals) double ovulation in mares.
• The secondary goal was to identify whether the rate of occurrence of these double ovulations changes with different months or seasons.

Methodology

• The study monitored 506 cycles from double ovulating mares at intervals of approximately eight hours before expected ovulation until 96 hours after the initial ovulation.
• The mares were categorized according to their ovulation intervals and the month/season.
• Asynchronous ovulation was defined as ovulations that were either eight hours or 24 hours apart.

Findings

• The study found a significant difference between the number of mares exhibiting asynchronous double ovulations (65.8% when defined as eight hours apart and 28.5% when defined as 24 hours apart) and those showing synchronous double ovulations (34.2% and 71.5% respectively).
• More asynchronous ovulations occurred during the periods of seasonal transition.
• The research concludes that asynchronous double ovulation is a frequent occurrence.

Implications

• The findings underscore the importance of regularly monitoring mares, especially during the extremes of the breeding season, to detect double ovulation within or at 96 hours post-initial ovulation.
• This thorough monitoring helps to minimize the chances of missing multiple pregnancies, which are difficult for the mare’s reproductive system to sustain to term.