Value of Urea Nitrogen in Rations Containing Different Carbohydrate Feeds

Abstract

The value of urea as a source of nitrogen in rations containing different carbohydrate feeds was determined in three series of digestion and nitrogen balance trials with Hereford steers. The carbohydrate feeds used in formulating the different rations were yellow corn, dehydrated sweet potatoes, milo, barley, cane molasses and combinations of cane molasses and corn. Each of these feeds was combined with prairie hay and sufficient protein supplement to provide basal rations having 7–8 percent crude protein. Urea in the form of “Two-Sixty-Two” was added to each ration in amounts required to provide a total of 11–12 percent protein equivalent. There were some differences among the basal rations in digestibility of nutrients ascribed to differences in the carbohydrate feeds. Addition of urea had very little effect on apparent digestibility of nutrients, other than protein (N×6.25) which was increased in all rations. It improved nitrogen retention to a significant extent when added to each ration, a greater improvement being made when it was added to the corn ration than when added to the molasses rations. Biological values calculated for the total nitrogen of the supplemented rations indicated that the urea nitrogen was utilized with equal efficiency in rations of different cereal grains and sweet potatoes, and with less efficiency in molasses-containing rations. In a comparison of urea with soybean meal in barley rations, small differences in nutrient digestibility and nitrogen retention favored the soybean meal supplement. Copyright © . .