29. The composition of poultry is very similar to that of meats. In
fact, poultry is composed of protein, fat, water, mineral salts, and
extractives that do not differ materially from those found in meats. The
protein, which usually varies from 15 to 20 per cent., is a much more
constant factor than the fat, which varies from 8 to 40 per cent. This
variation, of course, makes the total food value high in some kinds of
poultry and low in others. For instance, in a young broiler that has not
been fattened, the food value is extremely low; whereas, in a mature
well-fattened bird, such as a goose, which increases very markedly in
fatty tissue after reaching maturity, it is extremely high. A factor
that detracts considerably from the edible portion of poultry is the
waste material, or refuse. This consists of the bones, cartilage, head,
feet, and entrails, or inedible internal organs. The greater the
proportion of such waste material, the more the total nutritive value of
the flesh is reduced. It is claimed that birds that have light-colored
flesh do not become so fat as those which have dark flesh. This, of
course, makes their nutritive value less, because the fat of poultry is
what serves to supply a large part of the nutrition. There is no
particular difference, as is commonly supposed, between the red and
white meat of poultry. The difference in color is due to a difference in
the blood supply, but this does not affect the composition to
any extent.
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