Lamb Carcass Grading
USDA’s Dual Grading System
Yield Grade
1, 2, 3, 4, 5
expected yield of closelytrimmed cuts from the
leg, loin, rack, and
shoulder (80% of the
weight and 90% of the
value
Quality Grade
Prime, Choice,
Good, Utility, Cull
predicts expected
palatability (tenderness,
juiciness, flavor)
Determination of Class and Kind
Class – Ewe, Wether, Ram
1. Udder (smooth) or cod fat (rough)
2. Conformation
Kind – Maturity
1. Lamb (A/B)
P,C,G,U,C / 1 - 5




2 – 14 month
at least one perfect break joint
slightly dark, pink flank
round / red ribs
2. Yearling mutton
P,C,G,U / 1 – 5




12 – 25 month
spool or imperfect break joints
slightly to mod., dk. red flank
mod wide / flat/ reddish ribs
3. Mutton
P,C,G,U / 1 – 5




> 24 months
spool joints
dark to very dk. red flank
wide, flat, white ribs
Break joint versus Spool joint
USDA Yield Grade
Purpose to segregate
carcasses into cutablity
groups based on the
expected yield of closelytrimmed cuts from the
leg, loin, rack, and
shoulder (80% of the
weight and 90% of the
value
Expected Yields
YG 1 – 49.8% or more
YG 2 – 49.7% - 48.6%
YG 3 – 48.4% - 47.3%
YG 4 – 47.1% - 46.0%
YG 5 – 45.8% or less
USDA Yield Grade
USDA Yield Grades – 1, 2, 3, 4, 5
- Avg yield grade of US lamb
carcasses is upper 3
USDA YG = (10 x 12th rib fat) + 0.4
USDA Quality Grade
• Predicts the eating quality of cooked lamb
cuts from the Shoulder, Rack, Loin, and
Leg
– (Prime +,◦,-; Choice +,◦,-; Good +,◦,-; Utility, Cull)
– 90+% of U.S. lamb carcasses grade Pr or Ch
• Based on:
–
–
–
–
–
Maturity (lamb, yearling mutton, mutton)
Flank streaking (Traces, Slight, Small, Modest, etc.)
Conformation (Prime +,◦,-; Choice +,◦,-; Good +,◦,-)
Flank and fat firmness
Minimum fat thickness
Flank Streaking Classes
Carcass
Conformation
Pr°
Pr-
Ch°
Ch-
Gd+
Preliminary Quality Grade
Adjustments for Conformation
1. Must have minimum Prime PQG for Prime grade.
2. In P & Ch, superior PQG can compensate for inferior
conf. on an equal basis.
3. In Choice, superior conf. can compensate for inferior
PQG on an equal basis for 1/3 grade.
4. In Good, PQG and conformation can compensate for
each other on an equal basis for 1/3 grade.
Criteria for Placing Lamb Carcasses
1. Trimness / Fatness
2. Muscling
3. Dimension / Weight
Minimum Quality – Prime and Choice