Digestion and performance responses to lasalocid and concentrate supplements by beef cattle fed bermudagrass hay.

Beef cattle consuming bermudagrass hay were not supplemented or received a limited amount of ground corn alone or with a mix of protein meals to determine influences of concentrate supplementation on digestion and performance when the ionophore lasalocid (200 mg daily) was given. With limited feed intake, supplement treatment did not change the acetate to propionate shift in beef cows occurring with lasalocid (P < 0.06). Lasalocid did not affect sites of digestion of organic matter or nitrogen with any supplement treatment. However, lasalocid decreased (P < 0.10) ruminal digestion of neutral and acid detergent fibre. Live-weight gain by growing beef calves ingesting bermudagrass hay ad libitum was higher (P < 0.05) with than without supplementation and tended (P < 0.12) to be greater for corn plus protein meals than for corn alone. Lasalocid did not affect or interact with supplement treatment in feed intake or live-weight gain of heifers (236 kg; no growth stimulant) or steers (237 kg; treated with 200 mg progesterone and 20 mg estradiol benzoate). Lasalocid at 200 mg daily did not improve digestion characteristics or influence performance by beef cattle consuming a Basal diet of bermudagrass hay. Further, effects of lasalocid were not modulated by supplementation with concentrate, concentrate type or sex or growth stimulant usage.