e of weight of the
animal--the object the feeder has in view and desires to promote--the
supplying the waste of the tissues, and the process of respiration, both
of which are sources of loss of food, and which it must necessarily be
his aim to diminish as much as possible. The circumstances which must be
attended to in order to do this are sufficiently well understood. It has
been clearly established that the natural heat of the animal is
sustained by the consumption of a certain quantity of its food in the
respiratory process, during which it undergoes exactly the same changes
as those which occur during combustion. It has further been observed,
that the temperature of the body remains unchanged, whatever be that of
the surrounding air; and it is obvious that if it is to continue the
same in winter as in summer, a larger quantity of fuel (_i. e._ food)
must be consumed for this purpose, just as a room requires more fire to
keep it warm in winter than in summer, and hence it naturally follows,
that if the animal be kept in a warm locality the food is economized. It
may also be inferred that, if it were possible, consistently with the
health of the animal, to keep it in a room artificially heated to the
temperature of its own body, this source of waste of food would be
entirely removed. It is not possible, however, to do this, because a
limit is set to it by physiological laws, which cannot be infringed with
impunity; but the housing of cattle, so as to diminish this waste as far
as possible, is a point in regard to the propriety of which theory and
practice are at one.

The old feeders kept their cattle in large open courts, where they were
exposed to every vicissitude of the weather, but as intelligence
advanced, we find them substituting, first hammels, and then stalls, in
which the animals are kept during the whole time of fattening at an
equable temperature. The effect of this is necessarily to introduce a
considerable economy of the food required to sustain the animal heat;
but it also produces a saving in another way, for it diminishes the
waste of the tissues.

It has been ascertained by accurate experiments made chiefly on man,
that muscular exertion is one of the most important causes of the waste
of the tissues, and of increased respiratory activity. We cannot move a
limb without producing a corresponding consumption of matters already
laid up within the body; and it has also been found, that the difference