Physiological Manifestations of Endophyte Toxicosis in Ruminant and Laboratory Species

Abstract

Fescue alkaloid intake by cattle results in adverse metabolic effects that cause billion dollar losses annually to livestock production in the U.S. alone (Bacon et al., 1977; Garner and Cornell, 1978; Bush et al., 1979; Hoveland et al., 1980; Hemken, et al., 1981; Robbins, 1983; Wallner et al., 1983; Ball, 1984; Jackson et al., 1984ab; Stuedemann et al., 1985; Fribourg et al., 1991, 1995; Hoveland, 1991, 1993; Cross et al., 1995; Porter and Thompson, 1992; Strickland et al., 1993; Paterson et al., 1995), with the fescue toxicosis syndrome described as the major grass-induced toxicosis in the country (Cheeke, 1995). These estimates do not reflect losses attributable to the same alkaloids found in ergotized grains and grasses (Bacon et al., 1986, 1995; Coppock et al., 1989). Grasslands make up an increasing part of the world-wide ecosystem (Clay, 1991, 1993aó, 1994; Siegel and Bush, 1994; Hume, 1993), and endophytic fungi correspondingly infect a larger proportion of the grasslands each year. The presence of the endophyte of tall fescue in several countries gives the fescue toxicosis problem global significance (Siegel et al., 1984; Latch et al., 1984, 1987; Fletcher et al., 1990, 1993). For additional perspectives of important endophyte-infected forage relationships to animals, several reviews can be consulted (Read and Camp, 1986; Bacon, 1993, 1995; Buckner et al., 1979; Stuedemann and Hove-land, 1988; Porter and Thompson, 1992; Strickland et al., 1993; Thompson and Stuedemann 1993; Stuedemann and Thompson, 1993; Schmidt and Osborn, 1993; Prestidge, 1993; Thompson and Garner, 1994; Spiers et al., 1995b; Paterson et al., 1995; Porter, 1994, 1995; Cheeke, 1995; Joost, 1995, Cross et al., 1995).