Page:Popular Science Monthly Volume 22.djvu/400

386 animals, the range of variation being but little more than one half of one per cent. It should be stated that the much smaller percentage of offal parts, and the corresponding larger percentage of carcass, in the pigs, is partly to be attributed to the head and legs being included with the carcass of the pigs, while they are reckoned as offal parts in oxen and sheep. With sheep there was a rapid decrease in the percentage of offal parts as the animals fattened, while the percentage of carcass increased from 53·4 in the store condition to 64*1 in the very fat condition. There was, however, an actual increase in the offal parts from the store to the very fat condition in the proportion of one to one and three quarters, but the carcass parts made a greater actual increase, one pound in the store condition being raised to two and one half pounds in the very fat condition.

In connection with the data furnished by the mass of facts relating to the relative proportion of organs and parts of the body, which we can not discuss in detail, it became a matter of interest to ascertain the chemical composition of the increase of fattening animals obtained from different articles of food, so that the relations of the food constituents to the constituents of the increase could be determined. As a chemical analysis of a living animal can not be made, it is of course impossible to determine directly the chemical composition of the increase, as an analysis would be required at the beginning and at the close of the fattening period. The composition of the increase of fattening animals must therefore be determined by indirect methods, as by calculation from the data furnished by the differences in the composition of the food and the excretions; or from assumed constants, in the form of averages obtained by analyzing a large number of representative animals.

The most satisfactory data relating to this subject, that have ever been published, will be found in the results of the numerous analyses of the entire bodies and parts of animals, in different conditions as to fatness, that have been conducted at Rothamsted. Determinations were made of the fat, nitrogenous substance, and mineral matter of the entire body, and of certain separated parts, of ten animals, described as follows: 1. A fat calf, of the shorthorn breed, nine or ten weeks old, taken from its dam, feeding on grass; 2. A half-fat Aberdeenshire ox, about four years old, fed on fattening food, but which had grown rather than fattened; 3. A moderately fat Aberdeenshire ox, about four years old; 4. A fat Hampshire Down lamb, about six months old; 5. A Hampshire Down store sheep, about one year old;

6. A half-fat Hampshire Down ewe, three and one fourth years old;

7. A fat Hampshire Down sheep, one and a fourth year old; 8. A very fat Hampshire Down sheep, one and three fourths year old; 9. A store pig; 10. A fat pig. The pigs were of the same litter, and, when selected, were as nearly as possible alike, one weighing one hundred pounds and the other one hundred and three pounds. "One was