Are You Feeding Your Horse Enough Vitamin E?

Vitamin E is a fat soluble vitamin that is an essential nutrient in equine diets. Vitamin E functions largely as a biological antioxidant in the equine body protecting tissues from the oxidative effects of free radicals. Free radicals are a natural outcome of cell metabolism but they can become excessive during conditions of hard work or injury. 
The more active the cells are in your horse the more at risk he is of oxidative stress at the cellular level. This means that hardworking performance horses and growing horses are at particular risk of oxidative stress. Vitamin E also functions to enhance immunity at the intracellular level in our horses. 

Horses do not manufacture vitamin E in their own bodies and therefore need supplemental sources of it. Dietary sources include fresh forages such as pasture whole grains with the endosperm intact as well as fats and oil seeds. Horses that are deficient in vitamin E will have poor immunity and longer recovery times after injury or work due to oxidative stress on the cells within the body. Other nutritional antioxidant sources include carotenoids like beta carotene as well as vitamin C and selenium. 
What are the sources of vitamin E in the equine diet?
Vitamin E is a naturally occurring organic compound called alphatocopherol. Equine diets can contain either synthetic vitamin E dlalphatocopherol or natural vitamin E dalphatocopherol or both. Research in multiple species including humans has shown that the natural form of vitamin E is better utilized by the body and is more effective at raising blood serum or plasma vitamin E levels. 
Vitamin E in either the natural or synthetic form is very unstable and subject to deterioration so a form that has been esterified is generally added to any manufactured feeds or supplements. A common esterified form is called alphatocopheryl acetate. Esterified vitamin E sources are completely safe and effective and are rapidly converted back to nonesterified vitamin E in the digestive tract
How much vitamin E do horses need?
The 2007 NRC Equine Nutritional Guidelines provide minimum recommendations for vitamin E intake for horses at different body weights and different metabolic states. It suggests that a mature 500 kg horse at maintenance doing no work needs a minimum daily intake about 500 IU international units of vitamin E. The requirement doubles to a minimum intake of 1000 IU for the same horse doing hard work. Research has shown that horses