Lamb Grading Lecture Notes

Yield Grading* Predicts cutability.* Calculated based on Adjusted Fat Thickness (AFT) at the $12^{th}$ and $13^{th}$ rib.* Formula: $YG = 0.4 + (10 \times \text{Adjusted Fat Thickness})$.* Examples: YG 1.5 (AFT $0.11 \text{ in}$), YG 3.4 (AFT $0.30 \text{ in}$), YG 5.4 (AFT $0.50 \text{ in}$).### Quality Grading Overview* Predicts palatability.* Grades: Prime, Choice, Good, Utility, Cull.* Determined by Maturity, Flank Streaking, Conformation, and Fat Firmness.* Minimum lean and external fat firmness requirements for each grade: Prime (moderately firm), Choice (slightly firm), Good (slightly soft), Utility (soft).### Quality Grade Factors* Maturity: * Evaluated by spool/break joints, rib shape/color, and lean color/texture. * Young Lamb (A/B): break joints, pink/light red lean, fine texture. * Yearling Mutton: 0-2 break joints, slightly dark red, slightly coarse. * Mutton: 0 break joints ("spool joint"), dark red, coarse.* Flank Streaking: Visible fat deposits in the flank muscle, correlating with overall marbling.* Conformation: Overall carcass shape and muscling.* Minimum Fat Covering: Required for Prime and Choice grades.### Final Quality Grade Compensation* Superior Quality for Inferior Conformation: Compensates on a one-for-one basis, up to 1 full grade above the conformation grade.* Superior Conformation for Inferior Quality: Compensates for $1/3$ grade of inferior quality if conformation exceeds quality by $2/3$ grade.* No compensation for superior conformation if the quality is not Prime (e.g., Prime conformation cannot make a Choice carcass into Prime).* Ram carcasses can be discounted two full quality grades due to masculine development.### Lamb Sex Classes* Wether: Identified by cod fat.* Ewe: Identified by udder fat.* Ram: Identified by scrotal (cod) fat; "bucky" carcass appearance.