Utilization of Urea and Protein Nitrogen by Ruminants Fed High-Molasses and Sugar Rations

Abstract

Nitrogen balance trials were conducted with six Hereford steers to determine the comparative value of urea and soybean oil meal as nitrogen supplements in high-molasses rations. The basal ration, which was composed of about equal parts prairie hay and molasses supplemented with bone meal and salt, contained 5 percent protein, dry matter basis. The two supplemented rations, one containing 2 percent urea and the other containing 13 percent soybean oil meal, supplied 11 percent protein. Each ration was fed in equal amounts to two steers. Steers fed the basal ration lost an average of 60 lb. over a period of 3 months and were in negative nitrogen balance during balance trials. Those fed the supplemented rations maintained their weight and retained similar amounts of nitrogen, 13 to 17 percent of the intake. Estimated biological values from 57.6 to 65.5 for the supplemented rations indicated more efficient utilization of the soybean oil meal nitrogen, but the data were insufficient to warrant a positive conclusion.Both supplements increased the digestibility of nutrients in the basal ration, crude fiber digestion being increased from an average value of 55 percent in the basal to 68 percent in the urea ration and 72 percent in the soybean ration. The possible effect of different sugars on nitrogen utilization and digestion was studied in balance trials with 12 lambs fed 32 percent sucrose, glucose and lactose in separate but otherwise identical rations containing soybean oil meal as the protein supplement. Nitrogen retentions, biological values and nutrient digestibilities obtained with 11 lambs on each ration revealed no significant differences between the rations. Copyright © . .