Use of zilpaterol hydrochloride to reduce odor and gas production from the feedlot surfaces when beef cattle are fed diets with and without ethanol byproducts

Many malodorous compounds emitted from the feedlot surface of beef finishing facilities result from protein degradation. The inclusion of wet distillers grain with solubles IDGS) in beef finishing diets has been shown to increase odorous compounds in waste due to excess nitrogen excretion. Zilpaterol hydrochloride (ZH) is a supplement fed to cattle for a short period of time (21 days) near the end of the finishing phase to improve efficiency of lean gain. Improvements in feed efficiency and lean tissue accretion potentially decrease nitrogen excretion from cattle. Therefore, the use of ZH in feedlot diets, especially those containing WDGS, may reduce the concentration of odorous compounds on the feedlot surface. Sixteen pens of cattle (25-28 cattle/pen) were used in a 2 x 2 factorial study. Factors included 0 or 30% WDGS inclusion and 0 or 84 mg/steer daily ZH for 21 d at the end of the finishing period. Each of the four following treatment combinations were fed to 4 pens of cattle: 1) finishing diet containing 0% WDGS and 0 mg ZH, 2) finishing diet containing 30% WDGS and 0 mg ZH, 3) finishing diet containing 0% WDGS and 84 mg/animal daily ZH and 4) finishing diet containing 30% WDGS and 84 mg/animal daily ZH. A minimum of 20 fresh fecal pads were collected from each feedlot pen on six occasions. Samples were mixed within pen and a sub-sample was placed in a small wind-tunnel. Odorous volatile organic compounds, ammonia (NH₃), and hydrogen sulfide (H₂S) were measured. Inclusion of ZH was effective in lowering the concentration of total sulfides, total branched-chain fatty acids, and H₂S in fresh feces of cattle fed diets containing 30% WDGS. Ammonia concentration was not affected by the inclusion of either WDGS or ZH in the finishing diet.