Page:Popular Science Monthly Volume 22.djvu/402

388 matures, the mineral, the nitrogenous, and the fatty matters all increase in actual amount; but the percentage of both mineral matter and nitrogenous substance decreases, while that of the fat increases so as to much more than compensate for the decrease in that of the other solid matters. The result is that there is an increase in the percentage of total dry substance." The young animals, as the lamb and calf, had a larger proportion of water in the carcass than other animals in the same condition; and there was a larger proportion of bones in the carcass of the calf than in the carcass of the other animals.

In estimating the composition of the increase in live weight of fattening animals it was assumed that the composition of the original weight, that is, the weight at the beginning of the feeding period, was the same as in the "store" or "half-fat" animals that had been analyzed; and that the composition of the animal at the close of the feeding period was the same as that of the "fat" or the "very fat" animal that had been analyzed. By a proper exercise of judgment as to the comparative condition and quality of the animals at the beginning and end of the feeding period, and applying the data derived from the analysis of animals of similar quality, a close approximation to the composition of the increase could thus be obtained, and the probable error would be reduced to a minimum when the averages were made up from a large number of animals. In this way the composition of the increase was estimated in the case of ninety-eight fattening oxen, three hundred and forty-nine fattening sheep, and eighty fattening pigs, divided into numerous classes according to breed, condition of maturity, and description of food consumed. The estimated average percentage of mineral matters, nitrogenous substance, fat, and total dry substance, in the increase of these animals, is given in the following table:

The averages of all the animals under experiment, fed under a variety of conditions, and including the "fat" and the "very fat," are here given. In the tables which follow, however, data from selected cases are made use of, which do not change the general results, but represent, it is believed, more nearly, the results obtained in ordinary farm practice.

The percentage of mineral constituents in the increase of the sheep as given in the table is undoubtedly too high, from the presence of foreign matters in the wool which could not well be separated; this