IN the latest issue of the Journal of Animal Science, researchers at Clemson University and the University of Florida reported on a study that examined the impact of exercise on mare reproductive health and embryo transfer.
In the 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.
Partial-exercise mares were moderately exercised for 30 minutes daily during the periovulatory period and were rested after ovulation for seven days. Full-exercise mares were exercised for 30 minutes daily throughout the reproductive cycle.
According to the announcement from the American Society for Animal Science (ASAS), study results showed that exercise induced greater cortisol concentrations in horses. Cortisol has been shown to have effects on reproduction.
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-exercise groups, but the partial-exercise group had the lowest embryo quality score.
"This led us to conclude that exercise was just as detrimental, if not more so, to the time period just prior to and during fertilization," said Christopher Mortensen of the University of Florida who was one of the authors of the report.
The effect of exercise on early pregnancy is still an area that needs further investigation. Researchers are looking to study embryo quality because advancing technology has allowed embryo transfer to become a vital part of the horse industry, ASAS noted.
"What we hypothesize that 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," Mortensen said.
These findings could have implications for human pregnancy.
"While many studies in women have shown that intense exercise can be detrimental to female pregnancy, there are virtually no studies examining maternal exercise and effects on the early developing embryo. Furthermore, there are few studies examining stress and the female reproductive blood flow response," Mortensen said.