Fescue is a popular forage species because of the mutually beneficial relationship between the grass and the fungus. The relationship benefits the fungus by providing food, protection and a site for reproduction. The relationship also benefits the grass by providing protection from ruminant grazing and possibly insect attack. The fungus that infects fescue produces a number of products known as alkaloids that appear to cause problems for beef cattle. Animals displaying signs of fescue toxicosis typically exhibit a number of symptoms, including roughened hair coat, high body temperature, rapid breathing and excessive salivation.
Recent evidence shows that blood flow to peripheral and core body tissues is decreased.
Affected animals also have reductions in feed intake, weight gain, milk production and reproductive performance. Cattle grazing endophyte-infected fescue tend to spend less time grazing and more time in the shade or standing in water. The severity of summer fescue toxicosis is directly affected by environmental temperature. Dry-matter intake, respiration rates and rectal temperatures remain normal for cattle fed highly toxic fescue if environmental temperatures are cool. However, extreme lesions, including sloughing the tail switch and even the hooves, can occur in cattle grazing highly infected fescue during periods of cold environmental temperatures.