Influence of semen collection on salivary cortisol release, heart rate, and heart rate variability in stallions.

This study primarily focused on determining whether the process of semen collection induces a stress response in stallions. Researchers measured heart rate, heart rate variability, and cortisol levels in the saliva, and found that while heart rate increased during the procedure, overall stress levels did not significantly change, suggesting that semen collection is a modest and temporary stressor for sexually experienced, well-trained stallions.

Objective of the Study

• The core aim of the study was to determine the level of stress experienced by sexually mature and trained stallions during semen collection. This was done by tracking heart rate, heart rate variability, and salivary cortisol levels.

Methodology

• The study conducted on sixteen stallions, aged between 3-13 years, with prior sexual experience.
• Measurements were recorded over two consecutive days to ensure consistency and accuracy.
• The heart rate was continuously monitored for 30 minutes before and after the ejaculation to identify any directional changes.
• Cortisol concentration in saliva was taken from 60 minutes prior to and 120 minutes after the ejaculation.

Findings

• The heart rates of the stallions increased significantly during the semen collection procedure, but the day of collection, age, sexual experience, and the number of breeding seasons experienced by the stallion did not appear to influence this heart rate change.
• The measure of heart rate variability, i.e., the root mean square of successive RR differences, was unaffected by the semen collection procedures, further suggesting a consistent response to the procedure.
• Considering salivary cortisol levels, the researchers found no significant changes before and after the process, indicating that the procedure does not significantly impact stress hormone levels.

Conclusion

• The study concludes that semen collection procedure causes an increase in heart rate but does not alter heart rate variability or cortisol levels significantly, signifying that the process is not a high-level stressor for trained and sexually experienced stallions.
• The findings provide reassurance that the semen collection process is not overly stressful for healthy, experienced stallions, improving animal welfare during breeding operations.