Tall fescue has desirable compositional characteristics, withstands heavy grazing and environmental stresses. However, animal performance (body weight gains and reproductive efficiency) is depressed in animals grazing this forage. The signs exhibited by affected animals are exacerbated by elevated environmental temperatures and humidity. Affected animals have long, rough hair coats, excessive salivation and avoid sunlight. Increased respiratory rates arid body temperatures are also observed. Relative to reproduction, milk yields and pregnancy rates are depressed. No microscopic or gross lesions are associated with the general syndrome of fescue toxicosis.