The Influence of the Nitrogen Source on the Food Intake and Nitrogen Retention of Weanling Rats

Abstract
Variations in the food consumption of weanling rats, fed rations containing varying nitrogen sources, were largely associated with the apparent digestible energy (A.D.E.) content of the rations. A significant difference in the A.D.E. consumption of rats between nitrogen sources was attributed to the quality of the nitrogen sources. The higher the quality of the nitrogen source the greater the A.D.E. consumption. Evidence was presented to suggest that fibre in the diet tends to depress A.D.E. consumption. The higher physiological limit of food consumption was not attained even when the ration contained 65% of Alphacel. The nitrogen retention data stressed the importance of the ratio of apparent digestible energy to apparent digestible nitrogen (A.D.N.) of the food in controlling the percentage of A.D.N retained. It is possible that the optimum level of A.D.E. per gram of A.D.N. for all nitrogen sources studied (in respect to the growth of weanling rats) was within the range of 250 to 300 Cal.