Endophyte-free tall fescue improves cattle production

Abstract

A fungal endophyte was discovered infecting over 95% of tall fescue swards in the U.S. and also in European swards. This asymptomatic intercellular parasite appears to be transmitted only vertically, through infected seed. The fungus is associated with decreased animal performance. Specific toxin(s) produced by the fungus or by the fescue plant in response to the fungus has not been identified. Signs of toxicosis in cattle include increased body temperature, harsh hair coat, reduced serum prolactin, impaired reproduction, decreased rate of gain and/or milk production. Upon removal of cattle from toxic fescue to feedlots, performance is impaired 6 weeks or more. Replacement of infected fescue swards with new endophyte-free varieties greatly improves animal performance.