§ 53.152 Application of standards for grades of slaughter barrows and gilts.

(a) Grades of slaughter barrows and gilts are intended to be directly related to the grades of the carcasses they produce. To accomplish this, the slaughter barrow and gilt grades are predicated on the same two general considerations that provide the basis for the grades of barrow and gilt carcasses: (1) Quality of the lean, and (2) expected combined carcass 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 barrows and gilts with characteristics which indicate that the carcass lean will have acceptable quality and acceptable belly thickness and one for barrows and gilts with characteristics which indicate that the carcass lean will have unacceptable quality and/or the belly will be of unacceptable thickness. Since carcass indices of lean quality are not directly evident in barrows and gilts, some other factors in which differences can be noted must be used to evaluate quality. Therefore, the amount and distribution of external finish, firmness of fat, and firmness of lean are used as qualityindiesting factors.

(c) Barrows and gilts with characteristics which indicate that the carcass lean will have an unacceptable level of quality and/or the belly will be of unacceptable thickness are graded U.S. Utility. Also graded U.S. Utility—regardless of their development of other quality-indicating characteristics-are

slaughter barrows and gilts with indications that their carcasses will be soft and oily.

(d) Four grades—U.S. No. 1, U.S. No. 2. U.S. No. 3, and U.S. No. 4 are provided for barrows and gilts with characteristics which indicate that the carcass lean will have an acceptable level of quality. These grades are based entirely on the expected combined carcass yields of the four lean cuts.

(e) Average backfat thickness in relation to carcass length or live weight is used as a guide to expected yields of the

four lean cuts in these standards. In grading barrows and gilts, these factors normally are appraised visually; live weight is the only one that can be readily determined in the live animal. The average backfat thickness appraisal includes consideration of the distribution of fat on other parts of the animal in addition to those points on the back where it is measured on the carcass.

(f) Barrows and gilts will produce carcasses that vary in yields of four lean cuts because of variations in their degree of fatness (expressed as average thickness of backfat), and in their degree of muscling (thickness of muscling in relation to skeletal size). Since many slaughter swine have a normal development of muscling for their degree of fatness, in determining their grade the average thickness of backfat and carcass length or live weight are the only factors considered. These relationships are illustrated in Figure I for barrows and gilts weighing 170 to 350 pounds that will produce carcasses 27 to 36 inches long. For slaughter swine 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. 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 barrows and gilts of the same weight, the fatter animals 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 degrees are intended to cover the entire range of muscling present among slaughter swine. The degrees specified as typical for barrows and gilts 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 animals having a development of muscling which is different from that normally associated with their degree of fatness, the average backfat thickness-carcass length or average backfat thickness-live weight relationships for the various grades are different from those shown in Figure I.

Consideration is given such unusual developments of muscling as follows: In each grade, superior muscling is permitted to compensate for greater fatness at the rate of one full degree of superior muscling for a one-tenth inch increase in average backfat. Except for the U.S. No. 1 grade, the reverse type of compensation is also permitted and at the same rate; one-tenth inch less fat compensates for a

full degree of inferior muscling. In the U.S. No. 1 grade, this type of compensation is limited to one full degree of inferior muscling; barrows and gilts which have less than moderately thick muscling but which otherwise qualify for the U.S. No. 1 grade are graded U.S. No. 2.

(g) In no case, however, may variations-from-normal muscling alter the final grade more than one full grade.

normal

(h) In evaluating barrows and glits for fatness and muscling, variations in the degree of fatness have a greater effect on the yield of the lean cuts than do variations in muscling. The fatness and muscling evaluations can best be made simultaneously. This is accomplished by considering the development of the various parts based on an understanding

of how the appearance of each part is affected by variations in muscling and fatness. While the muscling of most swine develops uniformly, fat is normally deposited at a considerably faster rate on some parts than on others. Therefore, muscling can be appraised best by giving primary consideration to the parts least affected by fatness, such as the

ham. Differences in thickness and fullness of the ham-with appropriate adjustments for the effects of variations in fatness-are the best indicators of the overall degree of muscling in slaughter barrows and gilts. Conversely, the overall fatness of barrows and gilts can be determined best by observing those parts on which fat is deposited at a faster-thanaverage rate. These include the edge of the loin, the rear flank, the shoulder, the jowls, and the belly. As swine increase in fatness, these parts appear progressively fuller, thicker, and more distended in relation to the thicknes and fullness of the other parts, especially the thickness through the hams. In thinly muscled swine with a low degree of fatness, the width of the back usually will be greater than the width through the center of the hams. The back on either side of the backbone will appear sloping and flat. Conversely, in thickly muscled swine with a similar degree of fatness, the thickness through the hams will be greater than through the back and the back will appear full and well rounded. Very fat swine will be wider through the back than through the hams, but this difference will be greater in thinly muscled swine than in those that are thickly muscled. Such swine with thin muscling also will have a distinct break from the back into the sides, while those with thick muscling will be nearly flat on top but will have a less distinct break into the sides. As slaughter swine increase in fatness, they also become deeper bodied because of deposits of fat in the flanks and along the underline. The bulge of the flanks, best observed when the animal walks, and the thickness and fullness of the jowls are other indications of fatness.

(i) Barrows and gilts qualifying for the U.S. No. 1, U.S. No. 2, U.S. No. 3, or U.S. No. 4 grades may vary with respect to the relative development of the individual grade factors. In fact, some will qualify for a particular grade although they have some characteristics more nearly typical of another grade. Because it is impractical to describe the nearly infinite number of such recognizable combinations of characteristics, the

standards for each grade describe only barrows and gilts whose expected carcass yield of the four lean cuts is at the lower limit of each grade and which have a development of muscling that is normal for such swine.

(j) Other factors such as heredity and management also may affect the development of the grade-determining characteristics in slaughter swine. Although these factors do not lend themselves to description in the standards, the use of factual information of this nature is justifiable in determining the grade of barrows and gilts. The ability to make proper allowances for the effects of genetic and management factors on the appearance of grade-determining characteristics must be developed through experience.

[33 F.R. 9249, June 22, 1968]

§ 53.153 Specifications for official U.S. standards for grades of slaughter barrows and gilts.

(a) U.S. No. 1. Barrows and gilts in this grade will produce carcasses with acceptable lean quality and acceptable belly thickness and a high percentage of lean cuts. Swine 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 width through the hams is nearly equal to the width through the shoulders and both are wider than the back. The back is slightly full, is well rounded, and blends smoothly into the sides. The sides are moderately long and smooth. The rear flank is slightly full and its depth is less than the depth of the fore flank. The jowls are firm and slightly thick and full. 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 greater thickness of backfat. For example, a barrow or gilt with very thick muscling may have one-tenth of an inch more backfat than that indicated in Figure I as maximum for this grade 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 barrow or gilt be graded U.S. No. 1 with less than moderately thick muscling.

(b) U.S. No. 2. Slaughter barrows and gilts in this grade will produce carcasses with acceptable lean quality, acceptable belly thickness, and a slightly high percentage of lean cuts. Swine 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 width through the shoulders is slightly more than the width through the hams. The back is moderately full and is slightly rounded but with a slight break into the sides. The sides are slightly short and smooth. The rear flank is moderately full and its depth is slightly less than the depth of the fore flank. The jowls are moderately thick and full. 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 indicated in Figure I as maximum for the U.S. No. 2 grade at the rate of one full degree of muscling for one-tenth of an inch greater thickness of backfat. For example, a barrow or gilt with thick muscling may have one-tenth of an inch more backfat than that indicated in Figure I as maximum for this grade 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 barrow or gilt with slightly thin muscling may have one-tenth of an inch less backfat than that indicated in Figure I as maximum for this grade and remain eligible for the U.S. No. 2 grade.

(c) U.S. No. 3. Slaughter barrows and gilts in this grade will produce carcasses with acceptable lean quality and acceptable belly thickness and a slightly low percentage of four lean cuts. Swine 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 width through the shoulders is definitely greater than the width through the hams. The back is full and nearly flat with a pronounced break into the sides. The sides are short and smooth. The rear flank is full and its depth is equal to the depth of the fore flank. The jowls are thick and full. 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 indicated in Figure I as maximum for the U.S. No. 3 grade at the rate of one full degree of muscling for one-tenth of an inch greater thickness of backfat. For example, a barrow or gilt with moderately thick muscling may have one-tenth of an inch more backfat than that indicated in Figure I as maximum for this grade 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 barrow or gilt with thin muscling may have one-tenth of an inch less backfat than that indicated in Figure I as maximum for this grade and remain eligible for the U.S. No. 3 grade.

(d) U.S. No. 4. Barrows and gilts in this grade will produce carcasses with acceptable lean quality and acceptable belly thickness. However, they are fatter and less muscular and will have a lower carcass yield of the four lean cuts than those in the U.S. No. 3 grade.

(e) U.S. Utility. Barrows and gilts typical of this grade will have a thin covering of fat. The sides are wrinkled and the flanks are shallow and thin. Barrows and gilts in this grade will produce carcasses with unacceptable lean quality and/or unacceptable belly thickness. [33 F.R. 9250, June 22, 1968]

§ 53.154 Application of standards for grades of slaughter sows.

(a) The standards for grades of slaughter sows are based on (1) differences in yields of lean cuts and of fat cuts and (2) differences in quality of cuts. These characteristics vary rather consistently from one grade to another. The U.S. No. 1 grade has about the minimum degree of finish necessary to produce pork carcasses with quality characteristics indicative of acceptable palatability in the cuts. The U. S. No. 2 grade is overfinished and the U. S. No. 3 grade is decidedly overfinished in relation to the minimum finish associated with acceptable palatability. Yields of lean cuts are lower and yields of fat cuts are higher, in proportion to the degree of

overfinish, in these grades than in the U.S. No. 1 grade. Medium grade sows are underfinished and produce carcasses which are soft and have indications of insufficient quality for acceptably palatable cuts. Cull grade sows are decidedly underfinished and the pork is soft and watery with little or no marbling and low palatability.

(b) The grades for slaughter sows are closely related to the grades for sow carcasses, and the desired objective in grading sows is the accurate prediction of the carcass grade that will be produced. Degree of finish is an important factor in grading, and the expected average back fat thickness of carcasses produced by each grade of slaughter sows forms a part of the standards. The results of study of carcass measurement and cutting data show that carcasses equal in fat thickness are approximately equal in yields of cuts regardless of differences in weight. Therefore, the expected back fat thickness of carcasses from each grade of slaughter sows is the same at all weights. The following table outlines the carcass fat thickness guides for each grade of slaughter sows. Average back fat thickness

Grade:

(c) The standards for grades also include descriptive specifications of the characteristics of slaughter sows with the minimum degree of finish for each grade. Application of the standards requires an accurate appraisal of these live animal characteristics indicative of carcass finish and grade. No attempt is made to describe in the standards the many combinations of characteristics which may qualify an animal for a particular grade, and sound judgment is required to appropriately analyze varying combinations.

(d) Slaughter sows that have produced several litters of pigs may show considerable roughness along the underline due to extensive development of mammary tissue. In addition, SOWS from which pigs were weaned only a

short time prior to grading may show evidence that the mammary tissue is still active in milk production and not completely dry. Since smoothness and dryness of the underline have little effect on the basic grade determining factors, no provision is made in the standards for altering the grade of slaughter sows due to differences in these characteristics. It is recognized that the value determining factors to be considered in marketing sows include dryness and smoothness as well as such other factors as weight, degree of finish, quality, and fill. However, consideration of all such factors in determining grade would require a complicated system with a great number of grades in order to make each grade sufficiently restrictive to be practical and useful. Therefore, the grades outlined in these standards identify differences in slaughter sows with respect to yields of cuts and quality. They were designed as practical aids in evaluating slaughter sows when used in conjunction with other factors such as weight, fill, smoothness, and dryness.

[21 F. R. 6217, Aug. 18, 1956] § 53.155 Specifications

for official United States standards for grades of slaughter sows.

(a) U.S. No. 1 grade. U.S. No. 1 grade slaughter sows have an intermediate degree of finish near the minimum required to produce pork cuts of acceptable palatability. Sows with the minimum finish for U. S. No. 1 grade are moderately long and slightly wide in relation to weight. Width of body is rather uniform from top to bottom and from front to rear. The back, from side to side, is moderately full and thick with a well-rounded appearance and blends smoothly into the sides. The sides are moderately long and slightly thick; the flanks are slightly thick and full. Depth at the rear flank may be slightly less than depth at the fore flank. Hams are usually moderately thick and full with a slightly thick covering of fat. Jowls are usually moderately thick and full but appear trim. Sows in this grade produce U. S. No. 1 grade carcasses.