The Utilization of Simple Nitrogenous Compounds such as Urea and Ammonium Bicarbonate by Growing Calves

Summary 1.Two separate experiments involving the utilization of urea and ammonium bicarbonate nitrogen with 10 growing calves have been conducted. 2.The experiments indicate definitely that such nitrogen can be used for at least a partial supply of protein nitrogen. The most probable explanation is the production of protein by bacterial cell multiplication in the rumen and later digestion in the fourth stomach and intestine. Apparently most efficient utilization occurs when some soluble sugar such as corn molasses is fed in the ration. 3.With urea nitrogen constituting 43 per cent of the nitrogen of the ration the growth rate was but slightly less than that secured with a ration containing 66 per cent of its nitrogen as casein nitrogen. This does not imply that urea nitrogen in the ration used is superior to casein nitrogen. 4.Where casein nitrogen constituted 43 per cent of the total nitrogen of the ration, as in the case of animal No. 2, the growth rate over a period of 16 weeks was 1.5 pounds daily as compared with 1.3 pounds daily for the comparable level of urea nitrogen. 5.The nitrogen of ammonium bicarbonate was also utilized. 6.Analysis of the tissues at the end of the experiment indicated that the increments in weight with urea or ammonium bicarbonate nitrogen were of normal composition with a protein content similar to that of the casein fed animal. Extractable non-coagulable nitrogen was no greater in the leg tissues of the urea or ammonium bicarbonate animal than in the tissues of the casein animal.