The standards for pork carcasses developed by the United States Department of Agriculture, provide for segregation according to (a) class, as determined by the apparent sex condition of the animal at the time of slaughter, and (b) grade, which reflects quality of pork and the relative proportion of lean cuts to fat cuts in the carcass.

[17 F. R. 7864, Aug. 13, 1952]

§ 53.141 Pork carcass classes.

The five classes of pork carcasses, comparable to the same five classes of slaughter hogs, are barrow, gilt, sow, stag, and boar carcasses.

§ 53.142 Application of standards for

grades of barrow and gilt carcasses. (a) Grades for barrow and gilt carcasses are based on two general considerations: (1) Quality-indicating characteristics of the lean, and (2) expected combined yields of the four lean cuts (ham, loin, picnic shoulder, and Boston butt).

(b) With respect to quality, two general levels are considered: One for carcasses with characteristics which indicate that the lean in the four lean cuts will have an acceptable quality and one for carcasses with characteristics which indicate that the lean will have an unacceptable quality. The quality of the lean is best evaluated by a direct observation of its characteristics in a cut surface and when a cut surface of major muscles is available, this shall be used as the basis for the quality determination. The standards describe the characteristics of the loin eye muscle at the 10th rib. However, when this surface is not available, other exposed major muscle surfaces can be used for the quality determination based on the normal development of the characteristics in relation to those described for the loin eye muscle at the 10th rib. When a major muscle cut surface is not available, the quality of the lean shall be evaluated indirectly based on quality-indicating characteristics that are evident in carcasses. These

include firmness of the fat and lean, amount of feathering between the ribs, and color of the lean. The standards describe a development of each of these factors that is normally associated with the lower limit of acceptable lean quality. The degree of external fatness, as such, is not considered in evaluating the quality of the lean.

(c) Carcasses which have characteristics indicating that the lean in the four lean cuts will not have an acceptable quality or bellies too thin to be suitable for bacon production are graded U.S. Utility. Also graded U.S. Utility-regardless of their development of other quality-indicating characteristics-are carcasses which are soft and oily. Belly thickness is determined by an overall evaluation of its thickness with primary consideration being given to the thickness along the navel edge and thickness of the belly pocket.

(d) Four grades-U.S. No. 1, U.S. No. 2, U.S. No. 3, and U.S. No. 4-are provided for carcasses which have indications of an acceptable lean quality and acceptable belly thickness. These grades are based entirely on the expected carcass yields of the four lean cuts and no consideration is given to a development of quality superior to that described as minimum for these grades. The expected yields of the four lean cuts for each of these four grades are shown in Table I: TABLE I

Expected Yields of the Four Lean Cuts Based on Chilled Carcass Weight, by Grade 1 Grade

U.S. No. 1_. U.S. No. 2. U.S. No. 3.. U.S. No. 4.

Yield

53 percent and over.

50 to 52.9 percent.

47 to 49.9 percent. Less than 47 percent.

1 These yields will be approximately 1 percent lower if based on hot carcass weight. The yields shown in Table I are based on cutting and trimming methods used by the U.S. Department of Agriculture in developing the standards. (These cutting and trimming methods may be obtained from the Livestock Division, Consumer and Marketing Service, U.S. Department of Agriculture, Washington D.C. 20250.) Other cutting and trimming methods may result in different yields. For example, if more fat is left on the four lean cuts than prescribed in the USDA cutting and trimming methods, the yield for each grade will be higher than indicated. However, such a method of trimming, if

applied uniformly, should result in similar differences in yields between grades.

(e) Carcasses vary in their yields of the four lean cuts because of variations in their degree of fatness and in their degree of muscling (thickness of muscling in relation to skeletal size). Since many carcasses have a normal distribution of fat and a normal development of muscling for their degree of fatness, in determining their grade the actual average thickness of backfat and the carcass length or weight are the only factors considered. These relationships are illustrated in Figure I for carcasses either 27 to 36 inches long or weighing 120 to 255 pounds. For carcasses of other lengths or weights, average backfat thickness requirements for the various grades can be determined by an extension of the lines in this figure (NOTE: In cases where length and backfat thickness

indicate a different grade than weight and backfat, the grade shall be determined by using length.) In these standards the actual average thickness of backfat is an average of three measurements including the skin made opposite the first and last ribs and the last lumbar vertebra; carcass length is measured from the anterior point of the aitch bone to the anterior edge of the first rib next to the first vertebra; and hot carcass weight (or chilled carcass weight X 102 percent) is based on an entire carcass dressed packer style-split into two sides down the back, jowls attached, and head, ham facings, and leaf fat removed. When carcasses are not dressed according to packer style or when, through condemnations or for other reasons portions of the carcass have been removed, appropriate adjustments shall be made in carcass weight.

from normal

(f) In some carcasses the actual average thickness of backfat is not representative of their degree of fatness. In such cases, an appropriate adjustment is made in the average thickness of backfat and the grade is then determined as illustrated in Figure I. In evaluating the degree of fatnesss to determine whether it is representative of the actual average thickness of backfat, particular attention is given to the backfat thickness at points other than those used in determining the average and to the amount of fat in such areas as over the outside of the ham, at the juncture of the belly with the shoulder, directly anterior to the hipbone, and over the edge of the loin. For a carcass having a fat distribution indicative of a greater degree of overall fatness than that normally associated with its actual average thickness of backfat, the average thickness of backfat is adjusted upward. Likewise, for a carcass having a fat distribution indicative of a lesser degree of overall fatness than that normally associated with its actual average thickness of backfat, the average thickness of backfat is adjusted downward. In many carcasses, no adjustment is necessary. Although an adjustment in the average thickness of backfat of one-tenth of an inch is not uncommon, seldom should it exceed two-tenths of an inch.

(g) The degree of muscling specified for each of the four grades decreases progressively from the U.S. No. 1 grade through the U.S. No. 4 grade. This reflects the fact that among carcasses of the same weight, fatter carcasses normally have a lesser degree of muscling. For purposes of these standards, six degrees of muscling are recognized: Very thick, thick, moderately thick, slightly thin, thin, and very thin. These are intended to cover the entire range of muscling present among pork carcasses currently being produced. The degrees which are typical for carcasses at the minimum of the U.S. No. 1, U.S. No. 2, U.S. No. 3, and U.S. No. 4 grades are, respectively: Thick, moderately thick, slightly thin, and thin. For carcasses having a development of muscling which is different from that normally associated with their degree of fatness, the average backfat thickness-carcass length on carcass weight relationships for the various ure I. Consideration is given such unusual developments of muscling as follows: In each grade, a superior development of muscling is permitted to compensate for

a greater average backfat thickness at the rate of one-tenth inch greater backfat thickness for a full degree of superior muscling. Except for the U.S. No. 1 grade, the reverse type of compensation is also permitted at the same rate. In the U.S. No. 1 grade, this type of compensation is limited to one full degree of inferior muscling; carcasses which have less than moderately thick muscling but which would otherwise qualify for the U.S. No. 1 grade are graded U.S. No. 2.

(h) In no case, however, may the combined effect of variations-from-normal fat distribution and muscling alter the final grade more than one full grade from that indicated by the actual average backfat thickness and carcass length or weight.

(1) Since carcasses qualifying for the U.S. No. 1, U.S. No. 2, U.S. No. 3, and U.S. No. 4 grades may vary with respect to their average thickness of backfat, their length or weight, their development of muscling, and their distribution of fat, there will be carcasses which qualify for each of these grades in which the development of one or more of these factors is more nearly typical of another grade. Because it is impractical to describe the nearly limitless numbers of such recognizable combinations of these factors, the standards for each grade describe only carcasses whose expected yield of the four lean cuts is at the lower limit of each grade and which have a development of muscling and distribution of fat which is normal for such carcasses.

(j) The standards describe the development of the various grade factors as they appear in thoroughly chilled carcasses. However, carcasses with a lesser degree of chilling may be graded if there is reasonable assurance that after thorough chilling they will have indications of either acceptable or unacceptable quality of lean.

[33 F.R. 5082, Mar. 28, 1968]

§ 53.143 Specifications for official United States standards for grades of barrow and gilt carcasses.

(a) U.S. No. 1. Carcasses in this grade have an acceptable quality of lean, a high yield of lean cuts, and a low yield of fat cuts. For carcasses with minimum acceptable lean quality, the cut surface of the loin eye muscle at the 10th rib will be slightly firm, have a slight amount of marbling and be grayish pink

to moderately dark red in color. However, for intact carcasses, minimum acceptable quality of lean is indicated by a slight amount of feathering, fat that is slightly firm, and lean that is slightly firm and grayish pink to moderately dark red in color. The belly is at least slightly thick. Carcasses near the borderline between the U.S. No. 1 and U.S. No. 2 grades are thickly muscled in the hams, loins, and shoulders. The lower portion of the ham toward the hock is covered with a thin layer of fat, the back is well-rounded, the area at the juncture of the lower part of the shoulder and the belly is depressed in relation to the shoulder and the belly, and the area directly anterior to the hipbone is depressed in relation to the loin and ham. The maximum actual average thickness of backfat for carcasses in this grade will vary depending upon the distribution of fat, the development of muscling, and the carcass length or weight. For carcasses with a distribution of fat and development of muscling as described herein, the maximum average thickness of backfat increases from 1.3 to 1.6 inches with increases in either carcass length from 27 to 36 inches or carcass weight from 120 to 255 pounds (see Figure 1). A development of muscling superior to that specified as minimum for the U.S. No. 1 grade may compensate for a development of fatness which is greater than that indicated in Figure I as maximum for the U.S. No. 1 grade at the rate of one full degree of muscling for one-tenth of an inch increase in thickness of backfat. For example, a carcass which is 30 inches long and which has very thick muscling may have an average thickness of backfat of 1.5 inches and remain eligible for the U.S. No. 1 grade. The reverse type of compensation is also permitted-at the same rate-except that in no case may a carcass be graded U.S. No. 1 with less than moderately thick muscling. Also, in no case may the combined effect of variations in muscling and fat distribution from those described herein alter the final grade more than one full grade from that indicated by the actual average backfat thickness and either carcass length or weight.

(b) U.S. No. 2 Carcasses in this grade have an acceptable quality of lean, a slightly high yield of lean cuts, and a slightly low yield of fat cuts. For carcasses with minimum acceptable lean

quality the cut surface of the loin eye muscle at the 10th rib will be slightly firm, have a slight amount of marbling and be grayish pink to moderately dark red in color. However, for intact carcasses, minimum acceptable quality of lean is indicated by a slight amount of feathering, fat that is slightly firm, and lean that is slightly firm and grayish pink to moderately dark red in color. The belly is at least slightly thick. Carcasses near the borderline between the U.S. No. 2 and U.S. No. 3 grades are moderately thickly muscled in the hams, loins, and shoulders. The lower portion of the ham toward the hock is covered with a slightly thin layer of fat and the back is slightly well-rounded. The area at the juncture of the lower part of the shoulder and belly is slightly depressed in relation to the shoulder and the belly and the area directly anterior to the hipbone is slightly depressed in relation to the loin and ham. The maximum actual average thickness of backfat for carcasses in this grade will vary depending upon the distribution of fat, the development of muscling, and the carcass length or weight. For carcasses with a distribution of fat and development of muscling as described herein, the maximum average thickness of backfat increases from 1.6 to 1.9 inches with increases in either carcass length from 27 to 36 inches or carcass weight from 120 to 255 pounds (see Figure I). A development of muscling superior to that specified as minimum for the U.S. No. 2 grade may compensate for a development of fatness which is greater than that specified as maximum for the U.S. No. 2 grade at the rate of one full degree of muscling for one-tenth of an inch increase in thickness of backfat. For example, a carcass which is 30 inches long and which has thick muscling may have an average thickness of backfat of 1.8 inches and remain eligible for the U.S. No. 2 grade. The reverse type of compensation is also permitted at the same rate. For example, a carcass which is 30 inches long and which has an average thickness of backfat of 1.6 inches may have slightly thin muscling and remain eligible for the U.S. No. 2 grade. In no case may the combined effect of variations in muscling and fat distribution from those described herein alter the final grade more than one full grade from that indicated by the actual average backfat thickness and either carcass length or weight.

(c) U.S. No. 3. Carcasses in this grade have an acceptable quality of lean, a slightly low yield of lean cuts, and a slightly high yield of fat cuts. For carcasses with minimum acceptable lean quality, the cut surface of the loin eye muscle at the 10th rib will be at least slightly firm, have a slight amount of marbling, and be grayish pink to moderately dark red in color. However, for intact carcasses, minimum acceptable quality of lean is indicated by a slight amount of feathering, fat that is slightly firm, and lean that is slightly firm and grayish pink to moderately dark red in color. The belly is at least slightly thick. Carcasses near the borderline between the U.S. No. 3 and U.S. No. 4 grades are slightly thinly muscled in the hams, loins, and shoulders. The lower portion of the ham toward the hock is covered with a slightly thick layer of fat. The back is slightly flat and the edge of the loin is slightly full resulting in a slight break from the back into the side. In the area at the juncture of the lower part of the shoulder and the belly there is only a very slight depression in relation to the shoulder and the belly. In the area directly anterior to the hipbone there is only a very slight depression in relation to the loin and the ham. The maximum actual average thickness of backfat for carcasses in this grade will vary dependent upon the distribution of fat, the development of muscling, and the carcass length or weight. For carcasses with a distribution of fat and development of muscling as described herein, the maximum average thickness of backfat increases from 1.9 to 2.2 inches with increases in either carcass length from 27 to 36 inches or carcass weight from 120 to 255 pounds (see Figure I). A development of muscling superior to that specified as minimum for the U.S. No. 3 grade may compensate for a development of fatness which is greater than that specified as maximum for the U.S. No. 3 grade at the rate of one full degree of muscling for one-tenth of an inch increase in thickness of backfat. For example, a carcass which is 30 inches long and which has moderately thick muscling may have an average thickness of backfat of 2.1 inches and remain eligible for the U.S. No. 3 grade. The reverse type of compensation is also permitted at the same rate. For example, a carcass which is 30 inches long and which has an average thickness of backfat of

1.9 inches may have thin muscling and remain eligible for the U.S. No. 3 grade. In no case may the combined effect of variations in muscling and fat distribution from those described herein alter the final grade more than one full grade from that indicated by the actual average backfat thickness and either carcass length or weight.

(d) U.S. No. 4. Carcasses in this grade have an acceptable quality of lean but a lower expected yield of lean cuts than carcasses in the U.S. No. 3 grade.

(e) U.S. Utility. Included in this grade are all carcasses which have characteristics that indicate they will have a lesser development of lean quality than described as minimum for the U.S. No. 1, U.S. No. 2. U.S. No. 3, and U.S. No. 4 grades. Also included are all carcasses which do not have acceptable belly thickness and all carcasses-regardless of their development of other qualityindicating characteristics-which are soft and oily.

[33 F.R. 5083, Mar. 28, 1968]

§ 53.144

Application of standards for grades of sow carcasses.

(a) The standards for grades of sow carcasses are based on (1) differences in yields of lean cuts and of fat cuts and (2) differences in quality of cuts. There are rather uniform differences in these characteristics from one grade to another. The U.S. No. 1 grade has about the minimum degree of finish required to produce cuts of acceptable palatability. The four major trimmed lean cuts-hams, loins, picnics, and butts-normally make up more than 48 percent of carcass weight. The U. S. No. 2 and U. S. No. 3 grades have suc cessively higher degrees of finish resulting in lower yields of lean cuts and higher yields of fat cuts than U. S. No. 1 grade. Yields of lean cuts average 45 to 48 percent and under 45 percent of carcass weight, respectively, for U. S. No. 2 and U. S. No. 3 grades. In addition, the cuts from these grades have more fat remaining after trimming of external fat than do the cuts from U. S. No. 1 grade carcasses. Medium grade carcasses are underfinished and exhibit the lack of firmness and indications of little or no marbling (fat interspersed within the lean) associated with low palatability. Cull grade carcasses are decidedly underfinished and the pork is soft with very little evidence of marbling and is of low palatability.