The Utilization of Energy Producing Nutriment and Protein as Affected by the Level of the Intake of Beef Muscle Protein

Abstract

The influence of progressively greater protein contents of equicaloric diets was studied by means of feeding, metabolism and body analysis experiments with two groups, twenty-four each, of albino rats as subjects with quadruplet food control, the principal food protein being from beef muscle. One group was limited in food consumption to the approximate amount eaten in earlier experiments with casein as the principal food protein, and the other was allowed to eat 44.7% more. The most notable observations relating to the distribution of food energy were: 1) that the metabolizability of the diets diminished at a nearly regular rate from the 10% to the 45% protein diet; 2) that the heat production diminished slightly from the 10% to the 45% protein diet at a rate less than the accompanying decrease in metabolizable energy at the lower plane of nutrition, but greater than the decrease in metabolizable energy at the higher plane of nutrition; 3) that the body gain diminished materially at the lower plane of intake and increased slightly at the higher plane of food intake from the 10% to the 45% protein diet. The distribution of the food nitrogen and the composition of the body increase, as affected by the composition of the diets, were also observed. By comparison with earlier work it is shown that beef muscle protein does not have a greater heat stimulating effect than casein for growing rats.