Ovulation and the movement of the conceptus in the first 35 days of pregnancy in thoroughbred mares.

The research conducted on 937 Thoroughbred mares reveals no significant difference in ovulation activities between right and left ovaries, as well as equal pregnancy occurrences in right and left uterine horns. However, the study found more ovulations in the right ovary during September and December and in the left ovary during October and November. Notably, pregnant dry mares exhibited a significant bias toward the right uterine horn, while lactating mares favored the left.

Research Method

• The researchers have gathered and analyzed data from 937 Thoroughbred mares as a single population to study the activities of the right and left ovaries and the frequency of 35-day pregnancy occurrences in the right and left uterine horns.

Research Findings

• No distinguishing difference was found between the activities of the right and left ovaries or the frequency of 35-day pregnancies in the right and left uterine horns when the data was studied as a whole.
• Similar results were obtained when the data were further broken down and reviewed in years or sire groups.
• A significant trend was found in terms of ovulation patterns. More ovulations were recorded in the right ovary in the months of September and December while the left ovary saw increased activity in October and November.

Illuminating Variations

• The study discovered specificity in pregnancy localization based on the mare’s physiological state. Dry mares, those not producing milk, showed a significant bias towards pregnancies occurring in the right uterine horn. On the other hand, lactating mares displayed a higher amount of pregnancies in the left uterine horn.

Significance of Study

• This research draws attention to the fact that while ovulation activity does not notably differ between right and left ovaries, the time of the year and the mare’s physiological condition can play a crucial role in the organ’s functions.
• The findings also help widen the understanding of reproductive behaviours in Thoroughbred mares, potentially aiding in more proficient breeding practices.