Tall fescue is the most widely grown forage in the southeastern United States. Fescue toxicosis is the result of an endophytic fungus on tall fescue. A toxin produced by this endophytic relationship is absorbed into the digestive system of livestock that forage on the fescue. Unfortunately, the toxin remains active in cured hay as well. Research data from Experiment Stations in the southeast show serious production losses occurring in cattle. It is now also known that fescue toxicosis is causing critical reproductive problems in pregnant mares. Mares receiving most of their daily nutritional needs from fungus infected fescue tend to be agalactic, producing little if any milk. Although their foals are usually born live, they are often weak. Most do not survive long, due to lack of food intake or absence of the immune protection normally provided by the mare’s colostrum.