The determination of nitrogen balance indexes of protein hydrolysates in dogs.

where UN0 is the excretion of urinary nitrogen on a protein-free diet and K is the nitrogen balance index of the dietary nitrogen (1). This is an equation for a straight line in regions of negative and low positive nitrogen balance where this balance is linearly related to absorbed nitrogen. Thus the index (K), which is the rate of change of nitrogen balance with respect to absorbed nitrogen, is constant for any one protein in the region of negative balance. The index increases above normal, however, in hypoproteinemic dogs, animals with reduced protein stores. The data of Frost and Risser (2) demonstrate that a linear relationship exists also between nitrogen balance and absorbed nitrogen in dogs fed a fibrin hydrolysate intravenously. There is need toexpand these studies to investigate the application of Equation (1) to data obtained in animals fed hydrolysates intravenously. Experiments were planned, therefore, to determine under various experimental conditions the nitrogen balance indexes of different protein hydrolysates fed intravenously to normal and protein-depleted dogs. Methods Normal parasite-free adult dogs were used in these experiments. The composition of the diet was described previously (3). The animals received 70 calories per kilo of body weight per day based upon the probable weight of the dogs as calculated from Cowgill’s data (4).