Consequences For Captive Zebra Finches of Consuming Tall Fescue Seeds Infected With the Endophytic Fungus Acremonium coenophialum

Tall fescue (Festuca rundinacea) plants can be infected with the endophytic fungus Acremonium coenophialum. This fungus, which grows subcutaneously in leaves, stems, and seeds, does not undergo sexual reproduction or sporulate, and cannot survive outside the plant (Clay 1988). The fungus is passed from one generation to the next through infected seed. A mutualistic relationship exists between the grass and the fungus. The fungal endophytes produce ergopeptine alkaloids, notably ergovaline (Thompson and Stuedemann 1993), which makes the grass less palatable and more toxic to insect herbivores (Latch et al. 1985, Johnson et al. 1985) and nematodes (Kimmons et aL 1990). Because infected grasses are hardy (Arachevaleta et al. 1989) and resistant to insects, one infected cultivar (Kentucky 31) was widely planted before its infection was discovered. Hence, most of the plants grown on 14 million hectares of tall fescue pastures in the United States are infected (Shelby and Dalrympie 1987, Stuedemann and Hoveland 1988). Consumption of large amounts of fungus-infected tall fescue (hereafter called infected fescue) can have a deleterious effect on livestock. Cattle grazing infected fescue, especially in hot weather, have exhibited lower food intake, lower daily mass gains, higher rectal temperatures, and a decrease in reproductive rates (Hoveland et al. 1983, Aldrich 1993, Schmidt and Osborn 1993). These problems, however, can largely be avoided by proper management, allowing infected tall fescue cultivars to still be recommended