Animal age will have a sufficient effect on the palatability of the
cooked product. Carcasses from sheep are classed as lamb (12 to 14
months or less), yearling mutton (14 to 24 months), or mutton (over 2
years) on the basis of differences that occur in the development of
their muscular and skeletal systems. Differences in palatability
between the lamb and mutton meat are substantial. Meat from mutton
carcasses has a very intense flavor which is undesirable to some
individuals. Mutton is seldom marketed as retail cuts but rather as
soup stock or in further processed meat items.
A meat-type lamb carcass, when cut and trimmed according to the
methods described later, will yield over 70 percent of its carcass
weight in major trimmed cuts. Expected yields of retail cuts from a
yield grade 2 (trim) and a yield grade 4 (wasty) carcass are presented
in table 1.
_TABLE 1—Comparison of yield of retail cuts between USDA
yield 2 and yield grade 4 lamb carcasses_
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Percentage of carcass weight
Closely trimmed ---------------------------------
retail cuts Yield grade 2 Yield grade 4
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Leg, short cut.................... 22.2 19.4
Sirloin........................... 6.4 5.8
Short loin........................ 10.1 9.5
Rack.............................. 7.9 7.5
Shoulder.......................... 23.8 21.6
Neck.............................. 2.1 1.9
Breast............................ 9.8 9.8
Foreshank......................... 3.4 3.2
Flank (boneless stew)............. 2.3 2.3
Kidney............................ 0.5 0.5
Fat............................... 8.2 15.4
Bone.............................. 3.3 3.1
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Total......................... 100.0 100.0
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Adapted from Smith, King, and Carpenter, 1975.