THE EFFECT OF DIFFERENT PER CENTS OF PROTEIN IN THE DIET

Abstract

I. Results of feeding 5 different percentages of protein (10-26%) in an otherwise well-balanced diet to 90 pairs of rats indicate that when best growth is considered the amount of protein in the diet should be slightly in excess of 14%. A deviation of 4% less or greater produced no serious results. In addition, as the per cents of protein increase beyond the optimum, there was a progressive retardation in growth. Indications are that similar results would obtain if the per cent of protein were reduced progressively below the optimum.[long dash]II. Groups of young $ rats (I, II, III, IV, V) were fed on diets containing 10, 14, 18, 22, and 24% protein respectively and the following results were found. (1) The number of days intervening from the time they were placed in revolving cages until spontaneous running began was least in the group receiving the lowest % and in general increased as the protein content became richer. (2) The order of magnitude of the different groups for the 1st few wks. of activity, from the highest to the lowest, was III, II, I, V, and IV. (3) The total distance run, from greatest to least, was group III, 2795 miles; II, 2735; V, 2683; I, 2622; and IV, 2546. (4) If allowance be made for activity lost incident to reproduction the order, from greatest to least, was group II, 4133 miles; III, 4097; I, 3803; IV, 3197; and V, 3110. (5) A diet containing between 14 and 18% protein is best suited to the albino rat for maximal spontaneous running.