Researchers at several universities including Clemson University and the University of Florida have examined the impact of exercise on mare reproductive health and embryo transfer.
Mare with healthy foal
Exercised mares had more cortisol which has been shown to have effects on reproduction, and also embryo recovery rates were reduced in exercised horses.
In one study, researchers divided light-horse mares into three research groups: no exercise (control), partial-exercise and full-exercise. Their goal was to measure reproductive blood flow and embryo number and quality.
Partially exercised mares were moderately exercised for 30 minutes daily during the periovulatory period and rested after ovulation for seven days. Full-exercise mares were exercised for 30 minutes daily throughout the reproductive cycle.
Results from the study showed that exercise induced greater cortisol concentrations in horses. Cortisol has been shown to have effects on reproduction.
In addition, embryo recovery rates were reduced in exercised horses compared to the control group. There was no significant difference in embryo recovery rates for partial-exercise and full exercised groups, but the partial-exercised group had the lowest embryo quality score.
This led the researchers to conclude that exercise was just as detrimental, if not more so, to the time period just prior to and during fertilization.
The impact of exercise on early pregnancy is still an area that needs further research. Researchers are looking to study embryo quality because advancing technology has allowed embryo transfer to become a vital part of the horse industry.
Christopher Mortensen of the University of Florida, one of the authors of the study said, "What we hypothesize is the reduced hormone concentrations may be having an effect on the mare's oocytes, meaning they are not as 'competent' and have a reduced ability to be fertilized, or if fertilized, compromised embryo development.