Vitamin E also has an effect on a horses need to eat. A horse deficient in vitamin E will either not eat or be unable to eat normal quantities (such as a person recovering from anorexia) of hay or grain. When the horse becomes severely deficient it may take months, years or the horse may never recover to eating normal rations. This happens a lot with starved horses. I have witnessed and taken care of a horse first hand that I now own that was starved and couldn't eat even a quarter of a flake of hay and now is back to normal. It took a long time