Steer Performance on Tall Fescue Pasture

The tall fescue (Festuca arundinacea Schreb.) endophyte (Acremonium coenophialum Morgan‐Jones and Gams) has been associated with poor stocker cattle (Bos spp. L.) performance, but more information about management techniques using clover (Trifolium sp.) in pastures and the effect of cattle breed may help managers reduce the losses associated with the endophyte. This 3‐yr grazing study from early November to late May each year with yearling steers on ‘Kentucky 31’ tall fescue pasture evaluated the pasture effects of: (i) high endophyte (HE) with 76% infected fescue, (ii) HE with 74% infected fescue interseeded with a mixture of clovers (HE + Clo), and (iii) low endophyte (LE) with 0.7% infected fescue. A total of 173 Angus (AN) (B. taunts L.), Brahman (B. indicus L.)‐Angus (BA), and Simmental (B. taurus L.) × Brahman‐Angus (S × BA) 7‐ to 12‐mo old steers were used to study effects of grazing tall fescue on weight gains and rectal temperatures. Steers of all three breeds gained significantly faster on HE + Clo and LE pastures than on HE pastures. The interaction of fescue pasture treatment × breed for steer gain, however, was significant for the 196‐d grazing season because the BA steers gained faster than AN steers on all three pasture treatments. The BA steers gained 0.62, 0.48, and 0.19 lb/d more than the AN steers on HE, HE + Clo, and LE, respectively. The greatest reduction in steer gain for the HE pastures occurred from mid‐March to late May. Rectal temperature was affected only in late May with a significant pasture treatment × breed interaction. Rectal temperature of BA steers was not affected by the endophyte while temperatures for the AN and S × BA steers were higher for HE pastures than for LE pastures with the temperatures of HE + Clo pasture steers intermediate. These results suggest that clover in HE fescue can help overcome the detrimental effects of the endophyte and that cattle differ in ability to tolerate the toxic effects of the endophyte.