Page:Popular Science Monthly Volume 22.djvu/408

394 of the animal food consumed by man. It has been generally assumed that the effect of animal food, in human dietaries, is to increase the proportion of the nitrogenous constituents: from the results of these analyses, however, we can not escape the conclusion that the animal elements of a diet, as a whole, increase the proportions of the carbo-hydrates or non-nitrogenous constituents. It appears that two thirds of the nitrogen of the entire body, of the calf and bullocks, was found in the carcass, and of this twelve parts were in the bones, leaving fifty-four per cent of the whole nitrogen of the body in the soft parts of the carcass. Of the thirty-three per cent of the nitrogen of the entire body in the offal parts, it was estimated that in the calf seven to eight parts, and in the oxen four to five parts, would be consumed as human food. Of the total fat of the body, about seventy per cent in the calf, and rather more than seventy-live per cent in the oxen, were found in the carcass. Of the fat contained in the offal parts, it was estimated that five sixths in the calf and one fifth in the oxen would be consumed as human food. The percentage of the total nitrogenous and total non-nitrogenous constituents of animals, included in the food of man, has been tabulated by Drs. Lawes and Gilbert as follows:

According to this estimate, "there would be, in the fat calf analyzed, 1 time, in the fat ox 2 times, in the fat lamb, fat sheep, and fat pig nearly 4 times, and in the very fat sheep 6 times as much dry fat as dry nitrogenous constituents" in the parts of the animals consumed as human food. As one part of fat is equivalent to two and one half parts of starch, as a source of potential energy which must be taken as the measure of nutritive value, it will be necessary to estimate the fat in its equivalent as starch in making a comparison of vegetable and animal foods with reference to their nutritive value, and the relative ratio of their nitrogenous and non-nitrogenous constituents. On this basis the results of the Rothamsted analyses have been tabulated as follows: