Fescue Endophyte: History and Impact on Animal Agriculture

Abstract

Tall fescue (Festuca arundinacea Schreb.), a well adapted pasture grass in the eastern USA, has a reputation for poor animal performance. Discovery of an association between the fungal endophyte (Acremonium coenophialum Morgan-Jones and Gams) and fescue toxicosis in the 1970's made it possible to achieve high levels of animal performance on low-endophyte tall fescue. Steer average daily gain (ADG) has been 30 to over 100% higher on low-endophyte than on high-endophyte tall fescue pasture. It appears that for each 10% increase in endophyte level there is about 0.1 lb depression in ADG over an entire grazing season. Adverse effects of the endophyte have also been demonstrated in hay and seed. It has been shown to reduce milk production, and there are indications that it adversely affects reproduction. Intake is reduced on endophyte infected fall fescue. Although data are very limited, there are indications that sheep gains are reduced and that horses are afflicted by poor reproduction and agalactia. Much remains to be known about the mechanism of fescue toxicosis, but it is evident that with low- or endophyte-free tall fescue excellent animal performance can be achieved.