Thermoregulation of the testicle in response to exercise and subsequent effects on semen characteristics of stallions.

The research investigated how exercise affects the thermoregulation of a stallion’s testicles and the potential impact on semen parameters. It found that despite an increase in core body temperatures from relatively moderate exercise, testicular temperature changes were not significant, and no notable effects were observed on the semen.

Research Methodology

• The study involved eight stallions who were implanted with thermal sensory devices in their neck muscles and the subcutaneous tissue of their scrotum. They were then divided into two groups: one group that did not exercise (Non-EX) and another that did (EX).
• The EX group underwent exercise for thirty minutes per day, four days a week, over a twelve-week period from July to October 2010. This exercise was facilitated by a motorized equine exerciser.
• Temperatures of different areas in the body (subcutaneous scrotal, intramuscular neck, and rectal) were recorded at specific intervals- at the start of exercise, 22 and 30 minutes into the exercise, and 60 and 120 minutes post-exercise.
• Additionally, hourly data on ambient temperature and relative humidity were also recorded during the study period.
• Semen collection took place at the beginning, 4, 8, and 12 weeks into the study. The collected samples were analyzed for volume, sperm concentration, total sperm numbers, total and progressively motile sperm percentages, sperm morphology, and sperm DNA quality.

Results and Conclusions

• Results of the trial showed that exercise did not bring about any significant changes (P > 0.05) in the measured semen samples.
• The implanted thermal sensory devices did not have any acute or chronic effects on the scrotal or neck tissue. This confirms that they are a safe and effective method for measuring subcutaneous scrotal and neck temperatures.
• About 22 and 30 minutes into the exercise, rectal and neck temperatures of the stallions increased significantly (about 1.9 and 2.4°C, respectively). However, the increase in scrotal temperatures (approximately 0.8°C) was not significant.
• A correlation was observed between the temperature of scrotal, neck, rectal, and ambient temperatures, with the highest correlation being between scrotal and rectal temperatures.
• Despite the findings showing increased core body temperatures in the stallions, due to the exercise in high heat and humidity, it did not significantly increase scrotal temperatures. Consequently, there were no significant effects observed on the sperm parameters.