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.