Impact of moderate exercise on ovarian blood flow and early embryonic outcomes in mares.

The study explores the effects of different exercise regimes on the reproductive capacity of mares, particularly in relation to ovarian blood flow and embryonic outcomes. It concludes that exercise has a noticeable impact on ovarian arterial blood flow and the vascular perfusion of preovulatory follicles, and even a rest period after ovulation doesn’t improve embryonic recovery rates.

Study Design and Methodology

The mares involved in the study were divided into three groups: control (no exercise), partial exercise, and full exercise. The partial exercise group engaged in 30 minutes of moderate exercise daily during the periovulatory period and then were rested for seven days after ovulation. The full exercise group engaged in 30 minutes of daily exercise throughout the reproductive cycle. Both of these exercise regimes were compared to a control group that didn’t exercise.

All the mares were artificially inseminated during estrus and subjected to a process called uterine flush for embryo recovery approximately seven days post ovulation. Researchers used color Doppler ultrasonography to evaluate blood flow through the ovarian arteries and to assess vascular perfusion of the wall of preovulatory follicles.

Findings

The results of the study revealed several key findings:

• Exercise resulted in higher serum cortisol concentrations (a hormone linked to stress response).
• The rate of embryo recovery was reduced in exercised mares compared to the control group.
• There was no significant difference in embryo recovery rates between the partially and fully exercised mares.
• Quality Grade 1 embryos were recovered less frequently from the partially exercised mares compared to control and fully exercised mares.
• Exercise increased blood flow through both ovarian arteries leading up to ovulation.
• Vascular perfusion of the wall of the preovulatory follicle was reduced in both fully exercised and partially exercised mares compared to control group.
• When an embryo was successfully recovered, vascular perfusion of the follicle wall was found to be greater.
• There was no significant difference in follicle ovulatory diameter among exercised and non-exercised mares.
• When groups were combined, follicle diameter was greater when an embryo was recovered compared to unsuccessful recovery attempts.

Conclusion

The results showed that moderate exercise can increase ovarian arterial blood flow and, at the same time, decrease vascular perfusion of the wall of the preovulatory follicle. Contrary to expectations, resting mares after ovulation did not improve embryo recovery rates. This study suggests that exercise could have potential negative effects on equine reproduction, particularly the production and harvesting of quality embryos.