EFFECTS OF YEAST ON NITRATE TOXICITY IN DAIRY STEERS

Twelve Holstein steers were fed diets consisting of 1) corn silage and concentrate with yeast, 2) corn silage and concentrate without yeast, 3) alfalfa silage and concentrate with yeast and 4) alfalfa silage and concentrate without yeast to determine the effects of live yeast culture on nitrate toxicity. All steers were dosed with nitrate on a daily basis during the experimental period. Blood samples were analyzed for pH, partial pressure of carbon dioxide and oxygen, packed cell volume, hemoglobin and methemoglobin. Methemoglobin level increased (P<0.01) with time after initiation of nitrate feeding for all treatments. Results indicated that live yeast culture at 0.1% of the diet dry matter did not significantly reduce nitrate toxicity in steers.