flesh characteristics specified for the various grades are based on their appearance in the ribeye muscle of properly chilled carcasses that are ribbed between the 12th and 13th ribs. For carcass evaluation programs and other purposes, in the Prime and Commercial grades, each additional degree of marbling (up to three) greater than specified as minimum for each of these grades is equal to one-third of a grade of higher quality.

(q) References to color of lean in the standards for steer, heifer, and cow beef involve only colors associated with changes in maturity. They are not intended to apply to colors of lean associated with so-called "dark-cutting beef." Dark-cutting beef is believed to be the result of a reduced sugar content of the lean at the time of slaughter. As a result, this condition does not have the same significance in grading as do the darker shades of red associated with advancing maturity. The dark color of the lean associated with "dark-cutting beef" is present in varying degrees from that which is barely evident to so-called "black cutters" in which the lean is actually nearly black in color and usually has a "gummy" texture. Although there is little or no evidence which indicates that the "dark cutting" condition has any adverse effect on palatability, it is considered in grading because of its effect on acceptability and value. Depending on the degree to which this characteristic is developed, the final grade of carcasses which otherwise would qualify for the Prime, Choice, or Good grades may be reduced as much as one full grade. In beef otherwise eligible for the Standard or Commercial grade, the final grade may be reduced as much as onehalf of a grade. In the Utility, Cutter, and Canner grades, this condition is not considered.

(r) The yield grade of a beef carcass is determined by considering four characteristics: (1) The amount of external fat, (2) the amount of kidney, pelvic, and heart fat, (3) the area of the ribeye muscle, and (4) the carcass weight.

(s) The amount of external fat on a carcass is evaluated in terms of the thickness of this fat over the ribeye muscle, measured perpendicular to the outside surface at a point three-fourths of the length of the ribeye from its chine bone end. This measurement may be adjusted, as necessary, to reflect unusual amounts of fat on other parts of the carcass. In determining the amount of

this adjustment, if any, particular attention is given to the amount of fat in such areas as the brisket, plate, flank, cod or udder, inside round, rump, and hips in relation to the actual thickness of fat over the ribeye. Thus, in a carcass which is fatter over other areas than is indicated by the fat measurement over the ribeye, the measurement is adjusted upward. Conversely, in a carcass which has less fat over the other areas than is indicated by the fat measurement over the ribeye, the measurement is adjusted downward. In many carcasses no such adjustment is necessary; however, an adjustment in the thickness of fat measurement of one-tenth or two-tenths of an inch is not uncommon. In some carcasses a greater adjustment may be necessary. As the amount of external fat increases, the percent of retail cuts decreaseseach one-tenth inch change in adjusted fat thickness over the ribeye changes the yield grade by 25 percent of a yield grade.

(t) The amount of kidney, pelvic, and heart fat considered in determining the yield grade includes the kidney knob (kidney and surrounding fat), the lumbar and pelvic fat in the loin and round, and the heart fat in the chuck and brisket area which are removed in making closely trimmed retail cuts. The amount of these fats is evaluated subjectively and expressed as a percent of the carcass weight. As the amount of kidney, pelvic, and heart fat increases, the percent of retail cuts decreases-a change of 1 percent of the carcass weight in these fats changes the yield grade by 20 percent of a yield grade.

(u) The area of the ribeye is determined where this muscle is exposed by ribbing. This area usually is estimated subjectively; however, it may be measured. Area of ribeye measurements may be made by means of a grid calibrated in tenths of a square inch or by other devices designated by the Agricultural Marketing Service of the U.S. Department of Agriculture.1 An increase in the area of ribeye increases the percent of retail cuts-a change of 1 square inch in area of ribeye changes the yield grade by approximately 30 percent of a yield grade.

(v) Hot carcass weight (or chilled carcass weight x 102 percent) is used in determining the yield grade. As carcass

1 Information concerning such devices may be obtained from the Agricultural Marketing Service, Livestock Division.

weight increases, the percent of retail cuts decreases-a change of 100 pounds in hot carcass weight changes the yield grade by approximately 40 percent of a yield grade.

(w) The standards include a mathematical equation for determining yield grade. This grade is expressed as a whole number; any fractional part of a designation is always dropped. For example, if the computation results in a designation of 3.9, the final grade is 3-it is not rounded to 4.

(x) The yield grade standards for each of the first four yield grades list characteristics of two carcasses of two different weights together with descriptions of the usual fat deposition pattern on various areas of the carcass. These descriptions are not specific requirements-they are included only as illustrations of carcasses which are near the borderlines between groups. For example, the characteristics listed for Yield Grade 1 represent carcasses which are near the borderline of Yield Grades 1 and 2.

These descriptions facilitate the subjective determination of the yield grade without making detailed measurements and computations. The yield grade for most beef carcasses can be determined accurately on the basis of a visual appraisal.

[40 FR 11538, Mar. 12, 1975]

§ 53.103 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 hot X carcass weight, pounds) —,(0.32 x area ribeye, square inches).

(b) (1) The yield grade of a hindquarter, forequarter, or cut eligible for grading also is determined on the basis of the above equation in which the hot carcass weight is determined by multiplying the chilled weight of the cut by an appropriate factor as applicable to the cut and its style of preparation.

(2) The factors shown below shall be applicable to hindquarters and forequarters produced by ribbing as described herein, and to ribs, trimmed full loins, and trimmed short loins which are trimmed as described in Items 103, 172,

(3) A slightly larger factor, appropriate to reflect the weight of the cut as a percent of hot carcass weight, shall be used for ribs, full loins, or short loins which are more closely trimmed than described in the referenced IMP Specifications. Similarly, a smaller factor shall be used for determining the yield grade of these cuts when trimmed less closely than specified or when they include portions or all of adjacent cuts.

(4) In addition, for forequarters and forequarter cuts and for trimmed hindquarters and trimmed hindquarter cuts, the following standard percentages of kidney, pelvic, and heart fat, as applicable to the quality grade of the quarter or cut, also shall be used in the equation:

(5) For untrimmed hindquarters and for untrimmed hindquarter cuts, the quantity of kidney and pelvic fat is estimated as a percent of the hot side weight.

(c) 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. (1) 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 threetenths 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. (1) 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 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 fivetenths 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. (1) 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 seventenths 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 eighttenths inch of fat over the ribeye, 14.0 square inches of ribeye, and 4.5 percent of its weight in kidney, pelvic, and heart fat.

(4) Yield Grade 4. (1) 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. [30 FR 4459, Apr. 7, 1965 as amended at 38 FR 4763, Feb. 22, 1973]

§ 53.104 Specifications

for Official United States Standards for Grades of Carcass Beef (Quality-Steer, Heifer, Cow).

(a) Prime. (1) Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Prime grade vary in their other indications of quality as evidenced in the ribeye muscle. Minimum quality characteristics are described for two maturity groups which cover the entire range of maturity permitted in the Prime grade.

(2) Carcasses in the younger group range from the youngest that are eligible for the beef class to those at the juncture of the two maturity groups, which have slightly red and slightly soft chine bones and cartilages on the ends of the thoracic vertebrae that have some evidences of ossification. In addition, the sacral vertebrae are completely fused and the cartilages on the ends of the lumbar vertebrae are nearly completely ossified. The rib bones are slightly wide and slightly flat and the ribeye muscle is light red in color and is fine in texture. In carcasses throughout the range of maturity included in this group, a minimum slightly abundant amount of marbling

is required (see Figure 1) and the ribeye muscle is moderately firm.

(3) Carcasses in the older group range from those described above as representative of the juncture of the two groups to those at the maximum maturity permitted in the Prime grade, which have chine bones tinged with red and cartilages on the ends of the thoracic vertebrae that are partially ossified. In addition, the sacral vertebrae are completely fused, the cartilages on the ends of the lumbar vertebrae are completely ossified, and the cut surface of the lean tends to be fine in texture. The minimum degree of marbling required increases with advancing maturity throughout this group from minimum slightly abundant to maximum slightly abundant (see Figure 1) and the ribeye muscle is firm.

(4) Beef produced from cows is not eligible for the Prime grade.

(b) Choice. (1) Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Choice grade vary in their other indications of quality as evidenced in the ribeye muscle. Minimum quality characteristics are described for two maturity groups which cover the entire range of maturity permitted in the Choice grade.

(2) Carcasses in the younger group range from the youngest that are eligible for the beef class to those at the juncture of the two maturity groups, which have slightly red and slightly soft chine bones and cartilages on the ends of the thoracic vertebrae that have some evidence of ossification. In addition, the sacral vertebrae are completely fused and the cartilages on the ends of the lumbar vertebrae are nearly completely ossified. The rib bones are slightly wide and slightly flat and the ribeye muscle is moderately light red in color and is fine in texture. In carcasses throughout the range of maturity included in this group, a minimum small amount of marbling is required (see Figure 1) and the ribeye muscle may be slightly soft.

(3) Carcasses in the older group range from those described above as representative of the juncture of the two groups to those at the maximum maturity permitted in the Choice grade, which have chine bones tinged with red and cartilages on the ends of the thoracic vertebrae are partially ossified. In addition, the sacral vertebrae are completely fused, the cartilages on the ends of the lumbar vertebrae are completely ossified, and the

cut surface of the lean tends to be fine in texture. The minimum degree of marbling required increases with advancing maturity throughout this group from a minimum small amount to a maximum small amount (see Figure 1) and the ribeye muscle is slightly firm.

(c) Good. (1) Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Good grade vary in their other indications of quality as evidenced in the ribeye muscle. Minimum quality characteristics are described for two maturity groups which cover the entire range of maturity permitted in the Good grade.

(2) Carcasses in the younger group range from the youngest that are eligible for the beef class to those at the juncture of the two maturity groups, which have slightly red and slightly soft chine bones and cartilages on the ends of the thoracic vertebrae that have some evidence of ossification. In addition, the sacral vertebrae are completely fused and the cartilages on the ends of the lumbar vertebrae are nearly completely ossified. The rib bones are slightly wide and slightly flat and the ribeye muscle is slightly light red in color and is fine in texture. In carcasses throughout the range of maturity included in this group, a minimum slight amount of marbling is required (see Figure 1) and the ribeye may be moderately soft.

(3) Carcasses in the older group range from those described above as representative of the juncture of the two groups to those at the maximum maturity permitted in the Good grade which have chine bones tinged with red and cartilages on the ends of the thoracic vertebrae that are partially ossified. In addition, the sacral vertebrae are completely fused, the cartilages on the ends of the lumbar vertebrae are completely ossified, and the cut surface of the lean tends to be fine in texture. The minimum degree of marbling required increases with advancing maturity throughout this group from a minimum slight amount to a maximum slight amount (see Figure 1) and the ribeye muscle may be slightly soft.

(d) Standard. (1) Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Standard grade vary in their other indications of quality as evidenced in the ribeye muscle. Minimum quality characteristics are described for two maturity

groups which cover the entire range of maturity permitted in the Standard grade.

(2) Carcasses in the younger group range from the youngest that are eligible for the beef class to those at the juncture of the two maturity groups, which have slightly red and slightly soft chine bones and cartilages on the ends of the thoracic vertebrae that have some evidence of ossification. In addition, the sacral vertebrae are completely fused and the cartilages on the ends of the lumbar vertebrae are nearly completely ossified. The rib bones are slightly wide and slightly flat and the ribeye muscle is slightly dark red in color and is fine in texture. In carcasses throughout the range of maturity included in this group, a minimum practically devoid amount of marbling is required (see Figure 1) and the ribeye muscle may be soft.

(3) Carcasses in the older group range from those described above as representative of the juncture of the two groups to those at the maximum maturity permitted in the Standard grade, which have chine bones tinged with red and cartilages on the ends of the thoracic vertebrae that are partially ossified. In addition, the sacral vertebrae are completely fused, the cartilages on the ends of the lumbar vertebrae are completely ossified, and the cut surface of the lean is moderately fine in texture. The minimum degree of marbling required increases with advancing maturity throughout this group from minimum practically devoid to maximum practically devoid (see Figure 1) and the ribeye muscle may be moderately soft.

(e) Commercial. (1) Commercial grade beef carcasses and wholesale cuts are restricted to those with evidences of more advanced maturity than permitted in the Standard grade. Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Commercial grade vary in their other indications of quality as evidenced in the ribeye muscle. Minimum quality characteristics are described for the youngest and the most mature of these groups. The requirements for the intermediate group are determined by interpolation between the requirements indicated for the two groups described.

(2) Carcasses in the youngest group permitted in the Commercial grade range from those with indications of maturity barely more advanced than described as maximum for the Standard grade to

those with moderately hard, rather white chine bones and with cartilages on the ends of the thoracic vertebrae that show considerable ossification but the outlines of the cartilages are still plainly visible. In addition, the rib bones are moderately wide and flat and the ribeye muscle is moderately dark red and slightly coarse in texture. The minimum degree of marbling required increases with advancing maturity throughout this group from a minimum small amount to a maximum small amount (see Figure 1) and the ribeye muscle is slightly firm.

(3) The youngest carcasses in the most mature group included in the Commercial grade have hard white chine bones and the outlines of the cartilages on the ends of the thoracic vertebrae are barely visible, the rib bones are wide and flat, and the ribeye muscle is dark red and coarse in texture. The range in maturity in this group extends to include carcasses from the oldest animals marketed. The minimum degree of marbling required increases with advancing maturity throughout this group from a minimum moderate amount to a maximum moderate amount (see Figure 1) and the ribeye muscle is firm.

(f) Utility. (1) Depending on their degree of maturity, beef carcasses possessing the minimum requirements for the Utility grade vary in their other indications of quality as evidenced in the ribeye muscle. Carcasses within the full range of maturity classified as beef are included in the Utility grade. Thus, five maturity groups are recognized. Minimum quality requirements are described for three of these groups-the first or youngest, the third or intermediate, and the fifth or the most mature. The requirements for the second and fourth maturity groups are determined by interpolation between the requirements described for their adjoining groups.

(2) Carcasses in the first or youngest maturity group range from the youngest that are eligible for the beef class to those at the juncture of the first two maturity groups, which have slightly red and slightly soft chine bones and cartilages on the ends of the thoracic vertebrae that have some evidence of ossification. In addition, the sacral vertebrae are completely fused and the cartilages on the ends of the lumbar vertebrae are nearly completely ossified. The rib bones are slightly flat and the ribeye muscle is slightly dark red in color and fine in texture. In carcasses throughout the