A Comparison of High-Urea Supplements with Natural Protein Supplements for Growing and Fattening Beef Cattle

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Abstract
Five fat-tening trials with steer calves and 2 growing trials, 1 with steer calves and the other with yearling heifers, were conducted to compare the supplemental value of predominantly urea supplements with those of natural protein. A 64% protein supplement containing either 21 or 22% urea (42.5%) was used in 6 of the trials, and an 80% (28% urea) and a 96% (35% urea) protein supplement were used in 1 comparison. A liquid supplement (64% protein) was compared in 1 experiment. The fattening rations contained a full feed of high moisture ground ear corn plus limited corn silage. The growing rations contained either corn stover silage or corn silage plus the supplements being compared. The urea supplements were compared against a 32% protein supplement in which the protein was derived from natural sources. In 4 experiments, 7 comparisons involving high energy rations, predominantly urea supplements gave growth results which were not significantly different from those obtained from the use of a 32% protein supplement of natural sources. In one fattening trial, cattle fed the natural proteins gained significantly (P < .01) faster than those fed high-urea supplements. When a 64% protein, high-urea supplement was used in a growing ration with steer calves or with yearling heifers, such cattle gained significantly (steers, P < .01; heifers, P <.05) less than when natural proteins were used. A level of 14% molasses was equal to 28% molasses in the 64% protein formula, when added as a supplement to a fattening ration.