§ 54.105 - Specifications for official United States standards for grades of carcass beef (yield).

(a) The yield grade of a beef carcass is determined on the basis of the following equation: Yield grade—2.50+(2.50 x adjusted fat thickness, inches)+(0.20 x percent kidney, pelvic, and heart fat)+(0.0038 x hot carcass weight, pounds)—(0.32 x area ribeye, square inches).

(b) The following descriptions provide a guide to the characteristics of carcasses in each yield grade to aid in determining yield grades subjectively.

(1) Yield Grade 1. (i) A carcass in Yield Grade 1 usually has only a thin layer of external fat over the ribs, loins, rumps, and clods and slight deposits of fat in the flanks and cod or udder. There is usually a very thin layer of fat over the outside of the rounds and over the tops of the shoulders and necks. Muscles are usually visible through the fat in many areas of the carcass.

(ii) A 500-pound carcass of this yield grade which is near the borderline of Yield Grades 1 and 2 might have three-tenths inch of fat over the ribeye, 11.5 square inches of ribeye, and 2.5 percent of its weight in kidney, pelvic, and heart fat.

(iii) An 800-pound carcass of this yield grade which is near the borderline of Yield Grades 1 and 2 might have four-tenths inch of fat over the ribeye, 16.0 square inches of ribeye, and 2.5 percent of its weight in kidney, pelvic, and heart fat.

(2) Yield Grade 2. (i) A carcass in Yield Grade 2 usually is nearly completely covered with fat but the lean is plainly visible through the fat over the outside of the rounds, the tops of the shoulders, and the necks. There usually is a slightly thin layer of fat over the loins, ribs, and inside rounds and the fat over the rumps, hips, and clods usually is slightly thick. There are usually small deposits of fat in the flanks and cod or udder.

(ii) A 500-pound carcass of this yield grade which is near the borderline of Yield Grades 2 and 3 might have five-tenths inch of fat over the ribeye, 10.5 square inches of ribeye, and 3.5 percent of its weight in kidney, pelvic, and heart fat.

(iii) An 800-pound carcass of this yield grade which is near the borderline of Yield Grades 2 and 3 might have six-tenths inch of fat over the ribeye, 15.0 square inches of ribeye, and 3.5 percent of its weight in kidney, pelvic, and heart fat.

(3) Yield Grade 3. (i) A carcass in Yield Grade 3 usually is completely covered with fat and the lean usually is visible through the fat only on the necks and the lower part of the outside of the rounds. There usually is a slightly thick layer of fat over the loins, ribs, and inside rounds and the fat over the rumps, hips, and clods usually is moderately thick. There usually are slightly large deposits of fat in the flanks and cod or udder.

(ii) A 500-pound carcass of this yield grade which is near the borderline of Yield Grades 3 and 4 might have seven-tenths inch of fat over the ribeye, 9.5 square inches of ribeye, and 4.0 percent of its weight in kidney, pelvic, and heart fat.

(iii) An 800-pound carcass of this yield grade which is near the borderline of Yield Grades 3 and 4 might have eight-tenths inch of fat over the ribeye, 14.0 square inches of ribeye, 4.5 percent of its weight in kidney, pelvic, and heart fat.

(4) Yield Grade 4. (i) A carcass in Yield Grade 4 usually is completely covered with fat. The only muscles usually visible are those on the shanks and over the outside of the plates and flanks. There usually is a moderately thick layer of fat over the loins, ribs, and inside rounds and the fat over the rumps, hips, and clods usually is thick. There usually are large deposits of fat in the flanks and cod or udder.

(ii) A 500-pound carcass of this yield grade which is near the borderline of Yield Grades 4 and 5 might have one inch of fat over the ribeye, 9.0 square inches of ribeye, and 4.5 percent of its carcass weight in kidney, pelvic, and heart fat.

(iii) A 800-pound carcass of this yield grade which is near the borderline of Yield Grades 4 and 5 might have one and one-tenth inch of fat over the ribeye, 13.5 square inches of ribeye, and 5.0 percent of its weight in kidney, pelvic and heart fat.

(5) Yield Grade 5. A carcass in Yield Grade 5 usually has more fat on all of the various parts, a smaller area of ribeye, and more kidney, pelvic, and heart fat than a carcass in Yield Grade 4.