Beef Grading and Evaluation
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Transcript of Beef Grading and Evaluation
Beef Grading and EvaluationBeef Grading and Evaluation
Photo courtesy of the American Meat Science Association
Which one would you choose?
Think about the type of animal that might produce the best carcass.
How about now??
Two Grading SystemsQuality Grade - Age & marbling
PrimeChoiceSelectStandard
Yield Grade - muscle & fat
YG1YG2YG3YG4YG5
Carcass Quality Grading
1 Assumes that firmness of lean is completely developed with the degree of marbling and that the carcass is not a “dark cutter.”2 Maturity increases from the left to right (A through E).
3 The A maturity portion of the figure is the only portion applicable to bullock carcasses. Photo courtesy of the American Meat
Science Association
Photos courtesy of the American Meat
Science Association
Marbling Deposition
Changes in rib fat depth and marbling score relative to hot carcass weight at slaughter.
Bruns, Pritchard, Boggs,JAS 2004. 82:1315-1322
The Yield Grades are based on the following mathematical (regression) equation:
Yield Grade = 2.50 + (2.50 x adjusted fat thickness, in.) + (0.20 x % kidney, pelvic, and heart fat) + (0.0038 x hot carcass weight, lb.) – (0.32 x area of ribeye, sq. in.)
USDA Yield Grades
Photos courtesy of
the American Meat Science Association
Average Ribeye/Hot Carcass Weight
Measuring Fat Thickness External fat thickness is measured at the 12th/13th rib interface, perpendicular to the outside surface of the carcass at a point ¾ of the length of the ribeye from its chine-bone end.
Measuring Ribeye Area A grid calibrated in 0.1 sq. in. units may be used to measure the area of the ribeye muscle at the 12th/13th rib interface
Photos courtesy of the American Meat Science Association
Photos courtesy of the American Meat Science
Association
Photos courtesy of the American Meat Science
Association
Photos courtesy of the American Meat Science
Association
Starting Weight 885EndingWeight 1175Carcass Weight 715USDA Grade C-Backfat (in.) 0.40KPH (%) 2.5Ribeye (in.) 11.5Yield Grade 3.04
Example #1 Example #1
Starting Weight 850End Weight 1105Carcass Weight 655USDA Grade CBackfat (in.) 0.20KPH (%) 2.0Ribeye (in.) 11.9Yield Grade 2.83
Example #2 Example #2
Starting Weight 928Ending Weight 1238Carcass Weight 763USDA Grade SBackfat (in.) 0.20KPH (%) 2.0Ribeye (in.) 12.6Yield Grade 3.02
Example #3Example #3
Starting Weight 880Ending Weight 1249Carcass Weight 827USDA Grade S+Backfat (in.) 0.35KPH (%) 2.5Ribeye (in.) 15.9Yield Grade 1.93
Example #4 Example #4
Activity
• Complete the yield grade calculation activity.
Yield Grade Formula
• Yield Grade = 2.5 » + 2.5 X Adjusted Fat thickness ( BF)» + .0038 X Hot Carcass Weight» + .2 X Kidney Pelvic and Heart Fat % (KPH)» - .32 X Rib Eye Area (REA)
Calculate The Yield Grades
• Steer# BF HCW KPH REA• 1 .54 773 2.5% 14.1• 2 .33 865 1.5% 9.8• 3 .44 668 3.5% 10.7• 4 .5 885 2% 18.5• 5 .6 995 4% 15.3• 6 .8 700 4% 9.5
Answers
1. 2.452. 3.783. 3.44. 1.65. 3.76. 4.92
Carcass Grid
Carcass Grid
Questions?Photo courtesy of the American Meat
Science Association