The effects of ergot alkaloids on the breeding stallion reproductive system.

This research examines the impact of ergot alkaloids, toxins found in infected tall fescue grass, on the reproductive functions of breeding stallions. The study found that while these toxins reduced the gel-free volume in the ejaculate, they did not significantly affect other aspects of stallion fertility, such as sperm count, sperm motility, and testosterone levels.

Objectives

• Previous research has established that ergot alkaloids cause various health issues in mares, but their effect on stallions—particularly in relation to reproductive function—remains understudied. Hence, this research aimed to investigate these effects, specifically assessing their impact on spermiograms (a detailed assessment of sperm health) during stallion breeding soundness examinations.

Methods

• For the research, six stallions were involved in a crossover toxicology experiment where they were fed two different diets in separate periods. These diets consisted of 45% of endophyte-infected tall fescue seed, one being toxic, and the other being a non-toxic version.
• The provided diet was equal to 1% of the stallions’ body weight. They were fed for 70 days, rested (without any fescue seed) for at least 70 days, and then fed fescue again for another 70 days.
• The researchers performed regular blood samplings and breeding soundness examinations throughout the experimental period to monitor the effects.

Results

• Indications of systemic toxicity appeared approximately 8.33 hours after the initiation of the toxic seed intake, reaching a mean toxicity level of about 49.98 ng alkaloid per mg of creatinine.
• Once the feeding of infected seeds was stopped, the systemic alkaloid concentration fell to control (baseline) levels within 48 hours.
• There were no appreciable changes in various sperm parameters, including sperm motility, sperm concentration, sperm cell morphology, and total number of sperm cells. Likewise, the number of breeding doses, testicular volume, baseline and human chorionic gonadotropin stimulated testosterone levels remained unaffected.
• The toxic seed consumption did not have effect on core body temperature and superficial scrotal temperature either.
• However, a noticeable drop occurred in the gel-free volume – the liquid component of the semen minus the coagulated part — of stallions consuming endophyte-infected tall fescue seed compared to those consuming the non-toxic variant.

Conclusion

• In conclusion, while ergot alkaloids affected the gel-free volume in stallion ejaculate, they fell short of inducing statistically significant effects on various other critical parameters in the spermiogram of adult breeding stallions.