The carcass of lamb or mutton may be classified based on a number of physical characteristics.
Parameters:
(1) maturity
(2) streakings of fat within flank muscles
(3) palatability categories
(4) yield
Maturity categories (based on maturity of muscular and skeletal systems):
(1) young lamb
(2) older lamb
(3) yearling mutton
(4) mutton
Flank fat streakings:
(1) abundant
(2) moderately abundant
(3) slightly abundant
(4) moderate
(5) modest
(6) small
(7) slight
(8) traces
(9) practically devoid
Categories of lamb carcass (based on maturity category and flank fat streakings):
(1) prime
(2) choice
(3) good
(4) utility
(5) cull (for mutton)
Yield grades of lamb, yearling mutton and mutton carcasses - based on thickness of external fat:
(1) yield grade 1: maximum adjusted fat thickness of 0.15 inch; fat patchy and thin
(2) yield grade 2: maximum adjusted fat thickness of 0.25 inch
(3) yield grade 3: maximum adjusted fat thickness of 0.35 inch
(4) yield grade 4: maximum fat thickness 0.45 inch
(5) yield grade 5: fat thickness > 0.45 inch; fat covers most of carcass
