15.81 16.8
Oats 11.85 28.8
Hay (mean of grasses) 9.40 17.9
Potato 2.81 6.9
Wheat straw 1.79 12.4
Turnip 1.27 1.8

It is especially note-worthy that those varieties of food, which common
experience has shewn to promote the fattening of stock to the greatest
extent, contain in many instances the smallest quantity of respiratory
or fat-forming elements relatively to their nitrogenous compounds. This
is especially the case with the different kinds of oil cake, the
leguminous seeds, clover, hay, and turnips. On the other hand, in the
grains the ratio is nearly that of one to three, or similar to that
found in fat cattle; while in the straw, the excess of the respiratory
elements is extremely great.

These facts appear at first sight to be completely at variance with the
composition of the increase of fattening animals, as ascertained by
Messrs. Lawes and Gilbert already referred to, and which have shewn that
for every pound of nitrogenous compounds, nearly ten pounds of fat are
stored within the animal; and it might be supposed that those kinds of
food which contain the largest relative amount of respiratory elements
ought to fatten most rapidly, and should be selected by the farmer in
preference to oil-cakes and similar substances. But there are other
matters to be considered, dependent on the complex nature of the changes
attending the absorption and assimilation of the food. It must be
particularly borne in mind that only a small proportion of the food
consumed is stored up within the body, and goes to increase the weight
of the animal. Even in the case of the milk, in which economy in the
supply of nutritive matters has been most clearly attended to by nature,
a considerable proportion escapes assimilation, and in the adult animal
a large amount of the food passes off with the excretions. The justice
of this position is apparent when it is remembered that an ox will go on
day after day consuming from a hundred weight to a hundred weight and a
half of turnips, three or four pounds of bean-meal or oil-cake, and a
considerable quantity of straw, although its daily increase in live
weight may not exceed a couple of pounds. And in this direction a very
fertile field of inquiry lies open to the agricultural experimenter; for
it would be mo