(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 Krayish 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 successively 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.

(b) The standards for grades of sow carcasses apply only to carcasses with the firmness appropriate to their degree of finish. However, carcasses which are typically soft or oily as a result of feeds producing soft or oily fat may be graded in accordance with the standards provided they are identified as soft or oily along with the grade.

(c) There are differences in the bellies of sow carcasses which are peculiar to the class. Increasing numbers of litters farrowed and raised by a sow result in greater development of mammary tissue and increasing roughness of the belly along the teat line with accompanying seediness. In addition, when pigs were weaned only a short time before the sow was slaughtered the mammary tissue still contains milk and the bellies are commonly termed "wet". However, the smoothness or dryness of bellies has little appreciable effect on the basic grade determining factors and the standards contain no provision for altering the grade of a sow carcass due to these belly characteristics. Rather than forming a part of the basis for grade, it is the intent of the standards that smoothness and dryness of bellies should be a separate consideration used in conjunction with grade, weight, and other factors in evaluating sow carcasses.

(d) Average back fat thickness measurements provide a reliable indication of the yields of cuts and the quality of cuts which determine the grade of sow carcasses. Therefore, indication of a specific range in back fat thickness for each grade forms a part of the standards for grade. Analysis of measurement and cutting data for sow carcasses reveals that yields of cuts are approximately equal in carcasses which are equal in fat thickness but widely different in weight. Thus, to maintain comparable yields in a grade at all weights, back fat thickness requirements for a grade are the same at all weights. This is in contrast to the standards for barrows and gilts, in which the fat thickness for a grade increases for heavier or longer carcasses in order to maintain yields of cuts. With practice in the grading operation, visual estimates of fat thickness may often replace actual measurements with satisfactory accuracy. The following table of measurements provides an objective guide in determining the grade of sow carcasses.

1 Average of three measurements, skin included, made opposite first and last ribs and the last lumbar vertebra.

(e) In addition to the measurement guides to grade, the standards also include descriptive specifications outlining the characteristics of SOW carcasses typical of the minimum degree of finish for each grade. Average back fat thickness is a major factor in grading, but more accurate appraisal of yields of cuts and quality of cuts is achieved in borderline cases by consideration of thickness of muscling, conformation of the major cuts, uniformity of fleshing and finish, firmness, and indications of marbling. However, in no case may the final grade of a carcass be more than one-half the width of a grade different from that indicated by average back fat thickness.

(f) The standards describe rather typical carcasses of each grade, and no attempt is made to describe the numerous combinations of characteristics that may qualify a carcass for a particular grade.

[21 F. R. 6215, Aug. 18, 1956] § 53.145 Specifications United States standards for grades of

Sow carcasses.

for official

(a) U.S. No. 1 grade. U.S. No. 1 grade sow carcasses have about the minimum degree of finish required to produce pork cuts of acceptable palatability. Meatiness and yield of lear cuts from carcass weight are slightly high. Yield of fat cuts is slightly low. The ratio of total lean and fat to bone is slightly high. Carcasses with the minimum finish required for U.S. No. 1 grade are moderately long and slightly wide in relation to weight. The back and loins are moderately full and thick with a well-rounded appearance. Hams are usually moderately thick and plump and are slightly full in the lower part toward the hock. Bellies are moderately long, slightly thick, and moderately uniform in thickness with a slightly thick belly pocket. Shoulders are slightly thick and full.

Carcasses are usually moderately wellbalanced and moderately uniform in fleshing and finish. There are moderate quantities of interior fat in the pelvic area, a slightly thin but moderately extensive layer of fat lining the inside surface of the ribs, and a slightly small quantity of feathering, or fat intermingled with the lean between the ribs. The lean is firm. Both exterior and interior fats are firm, white, and of excellent quality. Carcasses with back fat thickness qualifying them for the fatter one-half of the U. S. No. 1 grade but with thin muscling in the major cuts, uneven fleshing and finish, or thick and uneven bellies shall be graded U. S. No. 2. Carcasses with back fat thickness qualifying them for the thinner one-half of the U. S. No. 1 grade but with only a moderately thin and incomplete rib lining, a moderately small quantity of feathering, slightly thin bellies with moderately thin belly pockets, and moderately soft lean and fat shall be graded Medium.

(b) U. S. No. 2 grade. U. S. No. 2 grade sow carcasses have a higher degree of finish than the minimum required to produce pork cuts of acceptable palatability. Meatiness and yield of lean cuts from carcass weight are slightly low. Yield of fat cuts is slightly high. The ratio of total lean and fat to bone is moderately high. Carcasses with the minimum finish required for U. S. No. 2 grade are slightly short and moderately wide in relation to weight. The back and loins are full and thick and are especially full near the edges. Hams are usually thick and plump and are moderately full in the lower part toward the hock. Bellies are slightly short, moderately thick, and rather uniform in thickness with a moderately thick belly pocket. Shoulders are moderately thick and full. Carcasses are usually well-balanced and uniform in fleshing and finish. There

are slightly large quantities of interior fat in the pelvic area, a slightly thick and rather extensive layer of fat lining the inside surface of the ribs, and moderate feathering. The lean is firm. Both exterior and interior fats are firm, white, and of excellent quality. Carcasses with back fat thickness qualifying them for the fatter one-half of the U. S. No. 2 grade but with thin muscling in the major cuts, uneven fleshing and finish, or very thick and uneven bellies shall be graded U. S. No. 3. Carcasses

with back fat thickness qualifying them for the thinner one-half of the U. S. No. 2 grade but with thick muscling in the major cuts, well-balanced fleshing and uniform finish, and slightly thick bellies shall be graded U. S. No. 1.

(c) U. S. No. 3 grade. U. S. No. 3 grade sow carcasses have a decidedly higher degree of finish than the minimum required to produce pork cuts of acceptable palatability. Meatiness and yield of lean cuts from carcass weight are low. Yield of fat cuts is high. The ratio of total lean and fat to bone is high. Carcasses with the minimum finish required for U. S. No. 3 grade are short and wide in relation to weight. The back and loins are very full and thick and are decidedly full at the edges. Hams are usually very thick and plump and are full in the lower part toward the hock due to a thick fat covering. Bellies are short and thick and uniform in thickness with a thick belly pocket. Shoulders are thick and full. Carcasses are usually well-balanced and uniform in fleshing and finish. There are large quantities of interior fat in the pelvic area, a moderately thick and extensive layer of fat lining the inside surface of the ribs, and slightly abundant feathering. The lean is firm. Both exterior and interior fats are firm, white, and of excellent quality. Carcasses with back fat thickness indicative of nearly minimum finish for the U. S. No. 3 grade but with thick muscling in the major cuts, well-balanced fleshing and uniform finish, and moderately thick bellies shall be graded U. S. No. 2.

(d) Medium grade. Medium grade Sow carcasses have a lower degree of finish than the minimum required to produce pork cuts of acceptable palatability. Yield of lean cuts from carcass weight is moderately high. Yield of fat cuts is moderately low. The ratio of total lean and fat to bone is moderately low. Carcasses with the minimum finish required for Medium grade are long and rather narrow in relation to weight. The back and loins are rather thin, lack fullness, and slope away from the center. Hams are usually slightly thin, lack plumpness, and taper toward the hock. Bellies are long and moderately thin and are somewhat uneven in thickness with

a thin belly pocket. Shoulders are moderately thin and flat. Carcasses tend to be uneven and lack uniformity of fleshing and finish. There are slightly small quantities of interior fat in the pelvic area, a thin and incomplete layer of fat lining the inside surface of the ribs, and only a small quantity of feathering. The lean is moderately soft with little evidence of marbling. Both exterior and interior fats are moderately soft, white to creamy white, and of moderately low quality. Carcasses with back fat thickness qualifying them for the fatter one-half of the Medium grade that are firm and have slightly thick bellies and belly pockets, a slightly thin but moderately extensive rib lining, and a slightly small quantity of feathering shall be graded U. S. No. 1. Carcasses with back fat thickness qualifying them for the thinner one-half of the Medium grade but with little or no rib lining and feathering, thin bellies and very thin belly pockets, and soft lean and fat shall be graded Cull.

The

(e) Cull grade. Cull grade sow carcasses have a decidedly lower degree of finish than the minimum required to produce pork cuts of acceptable palatability. Yield of lean cuts from carcass weight is high. Yield of fat cuts is low. The ratio of total lean and fat to bone is low. Carcasses with the degree of finish typical of the Cull grade are long and narrow in relation to weight. back and loins are thin and decidedly lacking in fullness with a definite slope toward the sides. Hams are usually thin and flat and taper toward the hock. Bellies are very long and thin and are uneven in thickness with a very thin belly pocket. Shoulders are thin and fiat. Carcasses tend to be uneven and lack uniformity of fleshing and finish. There are only small quantities of interior fat in the pelvic area, little or no fat lining the inside surface of the ribs, and scant feathering. The lean is soft and watery with very little evidence of marbling. Both exterior and interior fats are soft, creamy white to white, and of low quality. Carcasses with back fat thickness indicative of nearly maximum finish for the Cull grade that are only moderately soft and have moderately

or

The official standards for swine developed by the U.S. Department of Agriculture provide for segregation first according to intended use-slaughter feeder-then as to class, as determined by sex condition, and then as to grade, which is determined by the apparent relative excellence and desirability of the animal for a particular use. Differentiation between slaughter and feeder swine is based solely on their intended use rather than on specific identifiable characteristics of the swine. Slaughter swine are those which are intended for slaughter immediately or in the near future. Feeder swine are those which are intended for slaughter after a period of feeding.

[30 F.R. 16253, Dec. 30, 1965]

There are five classes of slaughter and feeder swine. Definitions of the respective classes are as follows:

(a) Barrow. A barrow is a male swine castrated when young and before development of the secondary physical characteristics of a boar.

(b) Gilt. A gilt is a young female swine that has not produced young and has not reached an advanced stage of pregnancy.

(c) Sow. A sow is a mature female swine that usually shows evidence of having reproduced or having reached an advanced stage of pregnancy.

(d) Boar. A boar is an uncastrated male swine.

(e) Stag. A stag is a male swine castrated after development or beginning of development of the secondary physical characteristics of a boar. Typical stags are somewhat coarse and lack balance the head and shoulders are more fully developed than the hindquarter parts, bones and joints are large, the skin is thick and rough, and the hair is coarse. [30 F.R. 16253, Dec. 30, 1965]

§ 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 qualityindicating 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.