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

Abstract

This problem has been studied, especially in Europe where protein concentrates are expensive. No attention, so far as we know, has been given to the problem in this country. The data from Europe are conflicting, some investigators claiming that polygastric animals can utilize for protein building simple nitrogen compounds like urea or ammonium bicarbonate, while others claim that they cannot. The foreign experiments have been balance experiments of short duration, which are always open to criticism, or experiments where urea, glycocoll or ammonium salts have displaced some of the protein for milk production. Here again the protein levels were sufficiently high so that the animals probably were receiving sufficient protein without a need for the nitrogen coming from simple forms like urea, glycocoll or ammonium salts. A complete review of this subject has been made recently by Krebs (1) and in this paper no further reference to the literature will be made. In this review by Krebs the conclusion was reached that the existing data on nitrogen balance experiments and protein displacement in lactation by urea or ammonium salts were inconclusive in respect to their utilization and that only long-time growth experiments could give conclusive data. This is in agreement with our own conclusions before inaugurating the experiments to be described.