Fungal endophyte effects on intake, health and liveweight gain of grazing cattle

Abstract

The direct effects of fungal endophyte-produced alkaloids on dairy beef cattle were determined in early summer 1992 and in autumn of 1993 and 1994. Endophyte level (nil vs high) or strain (wildtype vs selected 187BB) did not affect liveweight gain (LWG), but in 1994 weaners on nil endophyte consumed more dry matter than those on either endophyte treatment. The presence of clover enhanced LWG, reflected in higher dry matter intake in autumn 1993. Under the severe endophyte challenge of 1994, clover reduced the severity of ryegrass staggers even though the daily intake of lolitrem B was higher in the presence of clover. Under the rotational grazing management contrast imposed in 1994, followers had lower LWG than leaders and tended to have higher daily intake of lolitrem B. Grazing management effects on ergovaline intake were inconsistent and differed between endophyte strain and clover level. Animal responses to endophyte strain under contrasting conditions during each measurement period were related to daily alkaloid intake when scaled to liveweight. It is concluded that under the environmental conditions experienced in the Manawatu, endophyte alkaloids have minimal direct effect on cattle performance, although the reduction in ryegrass staggers by clover presence and its elimination by using a selected endophyte have important practical effects. Indirect effects through pasture production, composition or persistence may be more important to animal performance. Keywords: alkaloid intake, cattle, endophyte, ergovaline, herbage intake, liveweight gain, lolitrem B, peramine