Effects of Proportion of Supplemental Dietary Crude Protein Supplied by Urea on Performance and Carcass Characteristics of Beef Cattle Fed Steam-Flaked Corn-Based Diets with Wet Corn Gluten Feed1

An experiment was conducted to examine the effects of level of urea in steam-flaked corn diets containing 25% (DM basis) wet corn gluten feed on performance and carcass characteristics of beef steers. Crossbred steers (n = 240) were blocked by BW (average initial BW = 402.8 ± 10.75 kg) and assigned to dietary treatments consisting of 3 different ratios (N basis) of urea and cotton-seed meal (CSM): 1) 33% urea:67% CSM (33%); 2) 67% urea:33% CSM (67%); and 3) 100% urea:0% CSM (100%). There was a quadratic (P = 0.06) effect of the proportion of urea on ADG from d 0 to 56, and from d 0 to 112, ADG increased linearly (P = 0.09) as the proportion of urea in the diet increased. Additionally, DMI increased linearly (P = 0.001) with increasing urea level from d 0 to 28. For the entire feeding period, DMI tended (P = 0.14) to increase linearly with increasing proportion of urea. Gain:feed was affected quadratically (P = 0.09) by urea level; the maximum efficiency was noted for steers fed the 67% treatment. There was a tendency for a quadratic effect (P = 0.14) of urea level relative to hot carcass weight; cattle fed the 67% diet had the greatest hot carcass weight. Results indicate that with a steam-flaked corn finishing diet that contained 25% (DM basis) wet corn gluten feed, providing supplemental CP with a ratio of at least 67% urea:33% CSM (N basis) improved ADG and gain efficiency compared with 33% urea:67% CSM.