Temperature of the artificial vagina and its effect on seminal quality and behavioral characteristics of stallions.

This study investigates the effect of the temperature of artificial vaginas on the quality of collected stallion semen and the animals’ sexual behavior, concluding that temperatures above 45°C could potentially cause irreversible damage to the spermatozoa.

Study Design and Process

• The research involved the collection of stallion semen using artificial vaginas. These were set to temperatures of 44 to 46°C, 48 to 50°C and 52 to 54°C respectively. The aim was to assess any impacts of these temperature ranges on the quality of the collected semen and on the sexual behavior of the stallions.
• Several parameters were evaluated to determine semen quality: motility, gel volume, gel-free seminal volume, total seminal volume, and pH. Aspects of sexual behavior, including the number of mounts per ejaculate and total time to ejaculation, were also measured. These factors were observed and recorded across the varying temperatures to identify any potential correlations.
• In a further test, the spermatozoa were extracted, and then exposed to water-bath temperatures of 38°C, 45°C, 49°C, or 53°C for 1 minute. Their motility was measured after exposure to these controlled temperatures.

Study Findings and Conclusion

• The results showed that temperature variations in the artificial vaginas (from 44 to 54°C) had no significant effect on semen quality, as evidenced by unchanged motility, gel volume, gel-free seminal volume, total seminal volume, and pH. Similarly, the temperature did not affect the stallions’ sexual behavior as the number of mounts per ejaculate and total time to ejaculation also remained unchanged.
• When spermatozoa were directly exposed to water-bath temperatures, motility remained consistent at 38°C and 45°C. However, when exposure temperatures were increased to 49°C or 53°C there was a significant drop in spermatozoa motility. This suggests that temperatures above 45°C might damage the spermatozoa, possibly in an irreversible manner.
• Based on these findings, the researchers concluded that while collection temperature within an artificial vagina did not significantly affect the quality of the semen or sexual behavior of stallions, direct exposure of spermatozoa to temperatures in excess of 45°C may cause irreversible damage, affecting their motility and, therefore, potentially their fertilization ability.