Increased cortisol release and transport stress do not influence semen quality and testosterone release in pony stallions.

The article investigates the effect of stress, as measured by cortisol release, on the semen quality and testosterone release in pony stallions. Despite the increase in cortisol levels during transportation, the study found no negative effect on the stallions’ fertility.

Introduction

The study aimed to determine if stress, as evidenced by increased cortisol release due to transport, affects the fertility of breeding pony stallions used in equestrian competitions. This query arose due to the need to ensure that competition and transport to the competitions do not negatively impact the fertility of the stallions.

Methodology

• The experiment was designed with the use of Shetland stallions numbering 13.
• The effects of cortisol release induced by transportation were investigated using a 600 km road trip, a synthetic adrenocorticotropic hormone (ACTH) treatment, and a control place in a crossover design.
• Saliva samples were collected for cortisol analysis, while blood samples were collected for testosterone analysis.
• Semen samples were collected daily for 5 days after treatments and twice weekly for another 9 weeks.
• The team evaluated the total sperm count, sperm morphology, motility, and membrane integrity.

Hypothesis

The researchers hypothesized that increased cortisol levels might lead to a decrease in testosterone concentration and a decline in semen quality.

Results

• Cortisol levels increased significantly in response to transport and ACTH treatment but not to control treatments.
• However, despite these elevations, no alterations were observed in testosterone levels.
• The total sperm count did decrease with daily semen collections in the first week but showed no significant difference between treatments.
• There were no observed changes over time in the percentage of motile, progressively motile, membrane-intact, and morphologically defective spermatozoa from day 2 to day 6, and no differences were found between the treatments.

Conclusion

The study found that though road transportation induces a stress response mimicked by ACTH treatment, these stressors do not significantly impact testosterone release and semen quality. As such, testicular function in stallions seems to be adequately protected against transiently elevated cortisol concentrations. This suggests that stallions can be transported over longer distances without a negative impact on their fertility.