Vitamin E is considered the most important antioxidant and works closely with selenium to protect the body from the oxidative stress of exercise and illness. Found in high amounts in fresh pasture, levels begin to decay the moment pasture is cut for hay. That is why any horse that does not have access to grass, regardless of its activity level or health, would be a candidate for vitamin E supplementation. Horses are not very efficient in storing vitamin E and deficiency may be accelerated if the diet is deficient in selenium.
Selenium is a trace mineral that along with vitamin E function together to help to protect body tissues from free radical damage that occurs during oxidation (the conversion of feedstuffs into energy). While some parts of the country have high levels of selenium in their soil and therefore the plants that grow there, selenium deficiency is not uncommon and reported in many states. Therefore, most horses may require supplementation to meet the NRC requirement of 1-3 mg/day, depending on activity level. *NRC upper safe limit approx. 20 mg/day in total diet.
