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Encyclopedia Of Animal Science - B

Từ điển khoa học động vật vần B | Beef Carcass Composition and Quality Mark F. Miller Dale R. Woerner Texas Tech University Lubbock Texas U.S.A. INTRODUCTION Beef carcasses are sorted in a grading system regulated by the U.S. Department of Agriculture USDA Agricultural Marketing Service AMS Livestock and Seed Division LSD . When officially graded the grade of steer heifer cow or bullock carcass consists of the yield grade and or quality grade. USDA Yield Grade is an estimator of carcass composition and USDA Quality Grade is an indicator of carcass quality. USDA beef grades were created with the intention of developing a uniform marketing system for beef based on composition red meat yield and quality overall palatability . CARCASS COMPOSITION Beef Yield Grading The indicated yield of closely trimmed 1 2 inch of fat or less boneless retail cuts expected to be derived from the major wholesale cuts round sirloin short loin rib and square-cut chuck of a carcass is indicated by the USDA Yield Grade. 1 Yield grades are the most convenient and practical indicators of carcass composition that are utilized in the beef industry today. The beef yield-grading equation utilizes four measurable traits of each individual carcass. These include the amount of external fat subcutaneous the amount of kidney pelvic and heart fat perinephric the area of the ribeye longissimus dorsi and the hot weight of the carcass. The measured values of each of the four traits are placed into the yield-grading equation and result in values ranging from 1.0 to 5.9. Generally the calculated value is considered solely by its whole-number value. For example if the computation results in a designation of 3.9 the final yield grade is 3 it is not rounded to 4. 1 The USDA Yield Grade equation is as follows USDA Yield Grade 2.50 2.50 x adjusted fat thickness in inches 0.20 x percent kidney pelvic and heart fat 0.0038 x hot carcass weight in pounds 0.32 x ribeye area in square inches 1 The amount of external fat is measured by the thickness of