Effects of dietary urea concentration on performance and health of receiving cattle and performance and carcass characteristics of finishing cattle

Duff, G. C., Malcolm-Callis, K. J., Galyean, M. L. and Walker, D. A. 2003. Effects of dietary urea concentration on performance and health of receiving cattle and performance and carcass characteristics of finishing cattle. 83: 569-575. Can. J. Anim. Sci. 83: Effects of urea concentration for receiving and finishing cattle were examined. In exp.l, 197 newly received beef steers (188 kg) were used, and treatments included 0, 0.5, or 1.0% urea [dry matter (DM) basis] in a 70 or 75% concentrate (steam-flaked corn-based) diet. A quadratic response (P < 0.05) was observed for dry matter intake (DM1) of concentrate and total DM1 during days 0 to 14 with DM1 lower for 0.5% urea. A quadratic (P < 0.10) increase in gain:feed for 0.5% urea was noted during days 15 to 28 and days 0 to 28. Urea concentration did not affect bovine respiratory disease (BRD) morbidity. In exp. 2, 235 yearling beef steers (379 kg) and 126 yearling beef heifers (346 kg) were used to evaluate 0, 0.5, 1.0, 1.5, or 1.75% urea concentrations in a steam-flaked sorghum grain-based diet. Average daily gain (ADG) (1.44, 1.48, 1.51, 1.47, and 1.43 kg for 0, 0.5, 1.0, 1.5 or 1.75% urea, respectively), DM1 (9.4, 9.3, 9.6, 9.4, kg and 9.2 for 0, 0.5, 1.0, l.5 or 1.75% urea, respectively), and gain:feed (0.153, 0.160, 0.157, 0.157, and 0.157 for 0, 0.5, 1.0, 1.5 or 1.75% urea, respectively) did not differ (P > 0.10) among treatments for the overall experiment. No major differences were noted for carcass characteristics. Optimum level of dietary urea for newly received beef cattle fed 70 to 75% concentrate diets is approximately 0.5% of the DM for maximum feed efficiency and added urea concentrations did not alter performance or carcass characteristics to a great extent with steam-flaked sorghum grain-based finishing diets.