[Illustration: FIG. 5]
27. The term mutton is usually applied to the flesh of a sheep that is 1
year or more old, while lamb is the flesh of sheep under 1 year of age.
The popularity of these meats varies very much with the locality. In the
United States, a preference for lamb has become noticeable, but in
England mutton is more popular and is more commonly used. Both of these
meats, however, are very palatable and nutritious, so that the choice
of one or the other will always be determined by the taste or market
conditions.
[Illustration: FIG. 6]
28. Lamb that is 6 weeks to 3 months old is called _spring lamb_, and
usually comes into the market in January or February. The meat of sheep
1 year old is called _yearling_. Good mutton is cut from sheep that is
about 3 years old. Lamb may be eaten as soon as it is killed, but mutton
requires ripening for 2 or 3 weeks to be in the best condition for food.
Mutton differs from lamb very much as beef differs from veal, or as the
meat of any other mature animal differs from a young one of the same
kind. In mutton there is a smaller percentage of water and a larger
percentage of fat, protein, extractives, and flavoring substances.
There is also a difference in the appearance of these two meats. Lamb is
pink and contains only small amounts of fat, while mutton is brick red
and usually has considerable firm white fat. The bones of lamb are pink,
while those of mutton are white. The outside of lamb is covered with a
thin white skin that becomes pink in mutton. The size of the pieces of
meat often aids in distinguishing between these two meats, mutton, of
course, coming in larger pieces than lamb.
29. If there is any question as to whether the meat from sheep is lamb
or mutton, and it cannot be settled by any of the characteristics
already mentioned, the front leg of the dressed animal may be examined
at the first joint above the foot. Fig. 5 shows this joint in both lamb
and mutton. In lamb, which is shown at the left, the end of the bone can
be separated from the long bone at the leg, as indicated, while in
mutton this joint grows fast and looks like the illustration at the
right. The joint is jagged in lamb, but smooth and round in mutton.