Antioxidant Properties of Vitamin E Support Stallion Fertility

Offering stallions nutritional antioxidants can help improve the quality of semen. Higher quality semen may improve fertility rates when using cooled or frozen semen in artificial insemination programs, especially when stallions are classified as “bad freezers.”

Sperm, like other “high-energy” cells in the body, produce free radicals. At low levels, free radicals play important roles in various cellular pathways, such as the capacitation reaction that occurs prior to a sperm penetrating an egg. When excess levels of free radicals are produced, however, cellular damage can occur, impairing sperm function.

“Studies show that using antioxidants in semen extenders or directly supplementing stallions with antioxidants improves semen quality, presumably because antioxidants delay, prevent, or eliminate oxidative damage caused by the free radicals,” explained Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research.

Recently, scientists supplemented healthy Quarter Horse stallions with a commercial product containing the omega-3 fatty acid docosahexaenoic acid (DHA), L-carnitine, and various antioxidants, including vitamin E and selenium. Ejaculates were collected and evaluated for 60 days before supplementation and again for 60 days while the stallions were being supplemented.

“Several sperm parameters were improved when horses were supplemented with the antioxidant,” Crandell said. “Sperm volume was significantly higher, the number of sperm abnormalities observed visually under the microscope were significantly lower, and sperm mobility parameters including total motility and progressive motility were significantly better.”

Whether the benefits of this antioxidant supplement translate to semen samples that are cooled or frozen remains to be determined.

“This is an important next step because assisted reproductive therapies using fresh and frozen semen are widely used throughout the equine industry. Some stallions are known to be poor ‘coolers’ or ‘freezers’ so finding ways to maximize semen quality in these animals will improve fertility rates,” explained Crandell.

Kentucky Equine Research offers several high-quality antioxidant supplements, including vitamin E and coenzyme Q10.

“Nano E, a rapidly available natural-source vitamin E, demonstrates reproductive benefits for breeding stallions. This highly palatable, liquid form of vitamin E is more effective than synthetic vitamin E and is either easily top-dressed on a meal or dosed directly,” relayed Crandell.

Other research teams have proposed reproductive benefits of coenzyme Q10 supplementation, including better sperm motility in cooled semen and improved cryopreservation of semen from stallions with poor freezing ability. Another study provides direct evidence that CoQ10 supplementation helps subfertile stallions. Read more about these studies. Use research-proven Nano-Q10 as a source of coenzyme Q10.

^*Rojas, E.D., D.I. Carrillo Moreno, V.C. Villarreal, et al. 2023. Effect of nutraceutical supplementation on semen quality in stallions. Veterinary Medicine and Science 9(6):2600-2605.