LAUSR

This experiment evaluated the impacts of supplementing a yeast-derived product (Celmanax; Church & Dwight Co., Inc.; Princeton, NJ) during the finishing period on performance, physiological responses, and carcass quality of beef cattle. Ninety Angus-influenced steers (13 mo of age) were housed into a feeding facility equipped with Calan gates 2 weeks prior to the beginning of the experiment (d 0 to 133). Steer body weight (BW) was collected on d -3, -2, and -1, averaged, and represented steer initial BW (483 ± 3 kg of BW). On d 0, steers were ranked by initial BW to receive a finishing diet containing or not Celmanax at 16 g/steer daily (as-fed basis). Diet composition was (dry matter basis) 22% corn silage, 70.2% ground corn, 5% soybean meal, 1.8% mineral and vitamin mix, and 1% urea. Monensin (Rumensin 90; Elanco, Greenfield, IN) was included in the diet at 27.3 g/ton of dry matter. Steers received diets and treatments individually until slaughter on d 134. Voluntary feed intake was recorded daily throughout the experiment. Steer BW was recorded on d 131, 132, and 133, and averaged for final BW. Feed efficiency was calculated from each steer according to feed intake and BW gain during the 133-d experimental period, Blood samples were collected via jugular venipuncture on days 0, 60, and 133 and harvested for plasma. Hot carcass weight was collected upon slaughter, whereas trained personnel assessed carcass traits after a 24-h chill. No differences in BW gain, feed efficiency, feed intake, and carcass quality traits were observed between treatments (P > 0.25). No differences were also detected for plasma concentrations of glucose, insulin, somatomedin, and leptin (P > 0.33). Therefore, Celmanax inclusion into finishing diets containing monensin did not improve performance, physiological responses, and carcass quality of feedlot cattle.