ENDOPHYTE-INFECTED TALL FESCUE AND CONTROLLED GRAZING
Animal Science
Rebekah Norman
Agriculture & Natural Resource Agent III
University of Tennessee Extension
Murfreesboro
Abstract
ENDOPHYTE-INFECTED TALL FESCUE AND CONTROLLED GRAZING\r\n\r\nNorman* R.\r\n\r\nExtension Agent, University of Tennessee Extension, Rutherford County, Murfreesboro, Tennessee, 37129\r\n\r\n Tall fescue (Lolium arundinaceum) covers approximately 15 million hectares in the United States. This forage is the most widely adapted forage available in the transition zone which encompasses Tennessee, Kentucky, West Virginia, east to the Virginia Piedmont and western North and South Carolina, west to Arkansas and Missouri, and south to northern Mississippi, Alabama, and Georgia (Thompson et al., 1993). The forage offers ease of establishment, an acceptable nutrient profile, persistence through heavy grazing pressure and drought, and resistance to pests and diseases. However, it has been estimated that 95 percent of tall fescue pastures are infected with an endophyte fungus, Neotyphodium coenophialum, which produces alkaloids (Shelby and Dalrymple, 1987). These alkaloids are causative agents in “tall fescue toxicosis,” a serious production challenge to the beef industry and estimated to result in $609 million in lost production annually (Hoveland, 1993). Most alkaloid concentration is in the seedhead, crowns, and basal leaf sheaths. Signs of tall fescue toxicosis include reduced dry matter intake (DMI), weight gain, birth weights, fertility, and milk production. Additional signs include increased respiration rate, excessive salivation, and reduced serum prolactin levels. With a thorough understanding of factors impacting alkaloid production, alkaloid placement in the plant, temperature interaction, and cattle nutritional requirements as related to cow type, producers may use a controlled grazing system to manage tall fescue for maximum nutritional quality and reduced signs of tall fescue toxicosis.
Authors: Norman, R.
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Norman, R. Extension Agent II, University Of Tennessee Extension, Tennessee, 37129