Novel endophyte-infected tall fescue for growing beef cattle

ABSTRACT Tall fescue (Festuca arundinacea, Shreb.) is the predominant cool-season, perennial grass in the eastern half of the United States, and the majority is infected with the endemic endophyte (E+) Neotyphodium coenophialum, resulting in millions of dollars in revenues lost to the beef industry. Endophyte-free (E–) tall fescue was initially tapped as a “silver bullet” for the solution to fescue toxicosis, but drought intolerance and overgrazing have often resulted in nearly complete stand losses in 3 to 4 yr. Recently, the discovery of new endophytes that do not produce ergot alkaloids has resulted in the development of novel-endophyte-infected (NE+), stress-tolerant tall fescue plants. These NE+ tall fescue plants combine the plant persistence advantages of E+ (infected) tall fescue with the animal performance advantages of an E– tall fescue. Controlled studies from several locations in the southern United States have shown that the three commercially available cultivars of NE+ tall fescue persist as well as E+ tall fescues. Stocker cattle performance trials from five states have shown that the ADG in cattle grazing NE+ tall fescue was 47% greater than in cattle grazing E+ tall fescue and that cattle show no signs of fescue toxicosis. Economic evaluations of establishment cost and improved animal performance indicate that a stand of NE+ tall fescue would require 7 yr to pay off and begin to return profit to the enterprise if calves grazing E+ pasture are not discounted in price for fescue toxicosis at marketing. Average discounts at marketing for cattle showing signs of fescue toxicosis are $7.49/45.4 kg of BW. Assuming E+ cattle are discounted at sale and the quality of cattle is not decreased by the use of NE+ tall fescue, a stand of NE+ tall fescue would require 3 yr to pay the expense of establishment and begin to return profit to the enterprise.

Key Words: Festuca arundinacea, Acremonium coenophialum, Cattle, Endophytes

© 2004, by the American Society of Animal Science. All rights reserved.

J. Anim. Sci. 2004. 82(E. Suppl.):E75-E82

Implications

Novel endophyte-infected tall fescues seem to offer a solution to fescue toxicosis in stocker cattle; however, the ability of these new varieties to persist in many southern environments in the United States is open to question. Established stands of tall fescues infected with novel endophytes will allow for rates of gain by stocker cattle that are superior to those attained by cattle grazing endemically endophyte-infected tall fescues. However, because of the high cost of establishment for novel endophyte-infected tall fescues, analysis of returns on investments suggests that stands will require 3 to 7 yr to become profitable.