Beef Grading and Evaluation

1. Beef Grading and Evaluation Photo courtesy of the American Meat Science Association

3. Which one would you choose? Think about the type of animal that might produce the best carcass.

4. How about now??

5. Two Grading Systems Yield Grade - muscle & fat YG1 YG2 YG3 YG4 YG5 Quality Grade - Age & marbling Prime Choice Select Standard

6. 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

7. Photos courtesy of the American Meat Science Association

8. Marbling Deposition

9. Changes in rib fat depth and marbling score relative to hot carcass weight at slaughter. Bruns, Pritchard, Boggs, JAS 2004. 82:1315-1322

10. USDA Yield Grades 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.) Photos courtesy of the American Meat Science Association

11. 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 Average Ribeye/Hot Carcass Weight Photos courtesy of the American Meat Science Association

12. Photos courtesy of the American Meat Science Association

13. Photos courtesy of the American Meat Science Association

14. Photos courtesy of the American Meat Science Association

15. Example #1 Starting Weight 885 EndingWeight 1175 Carcass Weight 715 USDA Grade C- Backfat (in.) 0.40 KPH (%) 2.5 Ribeye (in.) 11.5 Yield Grade 3.04

16. Example #2 Starting Weight 850 End Weight 1105 Carcass Weight 655 USDA Grade C Backfat (in.) 0.20 KPH (%) 2.0 Ribeye (in.) 11.9 Yield Grade 2.83

17. Example #3 Starting Weight 928 Ending Weight 1238 Carcass Weight 763 USDA Grade S Backfat (in.) 0.20 KPH (%) 2.0 Ribeye (in.) 12.6 Yield Grade 3.02

18. Example #4 Starting Weight 880 Ending Weight 1249 Carcass Weight 827 USDA Grade S+ Backfat (in.) 0.35 KPH (%) 2.5 Ribeye (in.) 15.9 Yield Grade 1.93

19. Activity • Complete the yield grade calculation activity.

20. 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)

21. 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

22. Answers • 2.45 • 3.78 • 3.4 • 1.6 • 3.7 • 4.92

23. Carcass Grid

24. Carcass Grid

25. Questions? Photo courtesy of the American Meat Science Association