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Poultry

( Originally Published 1939 )



TECHNOLOGY

Production. The poultry industry produces and markets pre-dominantly chickens, turkeys, geese, guinea fowls, and pigeons. Chickens are kept on general farms in practically all sections of the country primarily to produce eggs, so that the great bulk of the market fowl from this source consists of young surplus males and old stock that have become unprofitable as layers. Much poultry is produced by the "battery" system of raising broilers out of season. On Long Island, N. Y., there is a highly specialized industry of operating duck-ling ranches. The raising and fattening of turkeys has also become an important commercial development in many parts of the country.

The smaller communities obtain their supplies from the surrounding country, but the larger population centers import their poultry by an average haul of at least 1000 miles. The great bulk of the chicken crop becomes available for market during the fall and winter, and turkeys are in especially heavy demand at the Thanksgiving and Christmas seasons. Much of the stock in these peak shipments is placed in cold storage to steady the price over a longer marketing period. These stocks reach their maximum in midwinter and their low point in the late summer or early fall.

If the producer lives near a city, he usually coops his poultry, and ships it alive to a dealer. If he is remote from such a market, he sells his stock to a local buyer who, in turn, sells to other dealers for assembly of carlot shipments to the large terminal markets. The birds are placed in coops constructed of wooden slats or rods, or frames covered with wire netting. Shipments are made in specially constructed live-poultry cars, having a series of coops or compartments built one above another along each side of the car, with an aisle down the center to facilitate cleaning the coops, and watering and feeding the stock. The outside of the car is covered with wire netting to provide ventilation. Shrinkage in weight during shipment may range from 2 to 15 percent or more. Specially fattened poultry shrinks more in shipment than other poultry. Crowding and rough handling may cause bruises and other substantial losses. As water in the coops is likely to spill, it is supplied in well-soaked corn.

Poultry is fattened for market to increase weight and to improve the quality of the flesh. The most common method is range fattening; the fowls forage about the farm and then are fed grain, usually corn, for a period of 1 to 3 weeks before they are marketed. Turkeys and guinea fowl are also fattened in this manner.

For certain high-class poultry for table, the birds are confined to a pen, and fed heavily a fattening ration for 2 to 3 weeks. This method is used on geese and on Long Island ducks.

Crate fattening is conducted for 8 to 10 days, especially for young chickens of broiler size or larger. The object is to keep the fowls quiet so that they will put on flesh, but the practice is not general.

In order to secure the best grade of packing stock for storage, the feeding of poultry is carefully regulated. Much of that raised on general farms is thin when received at the packing plants. The birds are put in feeding batteries and fed a fattening ration which contains buttermilk or skim milk, and ground grain in sufficient quantity to improve the texture and flavor of the meat. Such high-quality poultry is designated as "milk-fed"; much of the unfinished or farm-fed poultry is designated as "corn-fed" or "grain-fed." The butter-milk may be in the form of dry powder, or a paste known as a semi-solid buttermilk, containing about 30 percent total solids. On such a ration, young birds gain rapidly 15 to 35 percent in weight in 8 to 10 days, and hens about 5 to 15 percent? Little advantage is gained in fattening roosters, ducks, geese, and turkeys. Poultry that is shipped alive is not given this fattening treatment because of its adverse effect on their health and vitality. Intensive feeding before shipping would cause considerable loss from death and disease. For about '18 hours before killing, poultry is not fed but is given plenty of water. Intestinal bacteria can penetrate the walls of the digestive tract when it is distended with food.

Small shipments of dressed poultry may be packed in barrels with alternate layers of crushed ice. It is often in poor condition, particularly when allowed to lie in the more or less foul melted ice water.

Slaughter. The birds are suspended by their feet with heads down to facilitate bleeding. Improper bleeding leaves a darkened skin, particularly on the wings and hips. There are several methods of slaughter but the most common is the process of sticking. By a sharp knife thrust through the mouth, the jugular vein in the neck is cut first, then the point of the knife is run through the roof of the mouth and into the brain.

Kosher or orthodox Hebrew slaughter is conducted by a representative of the rabbi. The live chicken is brought by the purchaser to the official. He plucks a few feathers from the bird's throat, draws its head back, and severs the trachea and jugular vein by a single stroke of a carefully sharpened knife. The end of the trachea is then protruded through the opening. The bird is thrust head downward into a funnel to bleed, and then is given back to the purchaser to take home.

Dressing? When the feathers are to be removed by scalding, the well-bled bird is immersed in water at a temperature of 160° to 170° F. for a period of time just sufficient to facilitate their rubbing off easily. Overscalding cooks the skin and reduces the keeping quality of the stock. As soon as the feathers are removed, the bird is placed in water of the same temperature (160° to 170° F.) and then is quickly immersed in clean, cold, running tap water where it is left for 3 to 4 hours. The skin absorbs some moisture and becomes plumper; dry, scaly patches often develop soon after storing. In the last few years, the semi-scald method has been extensively practiced. The bird is dipped for about half a minute in a tank of water at a temperature of about 125° to 130° F. This facilitates the removal of the feathers by picking instead of rubbing, and gives an appearance of dry picking. The keeping quality may be almost as good as in dry picking, which is the oldest method and gives the best results in storage. As soon as the brain is pierced, the feathers are picked while they can be easily removed and before they become "set." The stock is then hung in coolers, and chilled to a temperature of about 32° F. for 24 hours. In wax-plucking, the carcass is coated with wax which is stripped off in sheets, taking with it feathers and pin-feathers.'

The technic of post-mortem inspection requires that the skin be cut between the leg and abdomen, and the legs be broken down so that the bird is set firmly on the inspection pan.' A circular incision in the abdomen allows the inspector forcibly to raise the breast and break the back, thereby exposing the internal organs. They are placed on a moving table or belt which carries them past the inspector. Any carcasses unfit for food are removed and placed in condemnation cans for denaturing. Good stock passes to the chopping block, where the heads and feet are removed, then on to the evisceration section, and finally to the washer.

Storage. Much investigation has shown that drawn poultry does not keep so well as undrawn poultry." 4 Under commercial packing conditions, more or less of the intestinal contents and microbial flora are smeared over the body cavity with attendant deterioration in quality of the meat during storage. Most of the dressed poultry in commerce is packed undrawn. However, improvements in cold-storage practices show that full-drawn poultry compares favorably in keeping quality with undrawn stock. The head, feet, and entrails are re-moved, and the giblets are cleaned and replaced in the body cavity. The carcass is then quick-frozen. The birds are graded usually as broilers, fryers, roasters, fowl stags, capons, and old cocks or roosters. The more desirable poultry are packed 12 in a box, and the lower grades are iced in barrels. For cold storage, they are quickly frozen in a sharp-freezer at a temperature near — 5° F. for 48 hours, and then held during the storage season as near 0° F. as possible. On ac-count of the low humidity in storage rooms, the dry air gradually absorbs the moisture from the poultry and causes dry, scaly spots known as "freezer burn" or "scald spots" to form on the skin. It is stated by Tressler that these are caused by the uneven drying out of the stored poultry, and there may be denaturation of the proteins under these dried areas so that the lost water cannot be absorbed again. The practice is to line the poultry boxes with parchment or waxed paper, and wrap the smaller birds individually. The boxes are stacked close together to reduce evaporation.

Canning. Poultry for canning has been prepared as whole and half chicken, boned chicken, chicken soup or broth, chicken à la king, deviled chicken, and chicken chop suey. The U. S. Department of Agriculture furnishes a quality grading service that is generally avail-able only for those carcasses that have been previously inspected and certified for condition and wholesomeness. Most of the canned poultry is handled under this inspection service (see page 300).

Defrosting. For consumption, the dealer may thaw the frozen poultry by immersing it in running cold water for 10 hours or so. This improves the appearance of the skin but reduces its keeping quality, removes some flavor, and slightly increases the weight. A better procedure is to hang the frozen stock in the dealer's refrigerator until the birds are defrosted (usually overnight is sufficiently long). They are then sold from the refrigerated showcase. Preferably the frozen poultry should be defrosted by the housewife just before she is ready to use it. This insures its use before any uncertain amount of deterioration sets in.

Turkeys. Turkey flesh is easily bruised, and most of the bruises on the dressed birds are caused by rough handling while alive. Before turkeys are killed, the crops should not contain food, but the birds should be given plenty of water. For slaughtering, they are suspended to the shackle so that they hang head downwards. A special knife is thrust into the roof of the mouth to cut the blood vessels and then to destroy the medulla oblongata. This allows ready bleeding and loosening of the feathers. The carcasses are dry-picked immediately to remove the large feathers, and then gone over again with the pruning knife to remove the pin-feathers. By this time, the bleeding has stopped. The carcasses are cleaned, torn skin sewed with needle and thread to protect the exposed flesh from bacterial invasion, and cooled fo 34° F. within 24 to 36 hours. They are then graded and usually packed in boxes or in barrels, lined with parchment paper. Some turkeys are marketed with a row of feathers remaining on each wing, and a few feathers on the neck and around the knees.

RELATION TO THE PUBLIC HEALTH

Nutritive value. The proximate composition of the flesh of poultry does not differ greatly from that of other meats, as indicated in Table XXII, from the compilations of Atwater and Bryant.

From these figures it is seen that poultry meat is low in mineral content. The fuel value comes almost entirely from the combustion of the fat and protein. Numerous investigations have shown that the meat contains no significant amounts of the various vitamins, except that canned chicken has been found to be useful as a pellagra-preventive food.' The chief nutritive value of poultry lies in the quality of its protein, its ready digestibility, and its palatability.

The light meat of the breast is more tender than the darker meat of the leg muscles. It is not quite so valuable biologically as casein. It contains less connective tissue and less fat, and is more easily and comfortably digested. Sherman states that there is no confirmation of the belief that light meat furnishes less of the substances which give rise to uric acid in the body.

The dark meat has 600 Sherman-Chase units of vitamin B per 100 grams, whereas the light meat has only about half as much. Chicken liver contains large amounts of vitamin B, C, and D.

Epidemiology. Poultry is subject to many diseases of bacterial causation closely related to similar diseases in man. Therefore, it is natural to suspect that poultry may be incriminated as agents in the transmission of similar illness to man.

The poultry inspection service of the U. S. Bureau of Agricultural Economics reports that among live poultry the young stock seem to be especially affected with roup, an infectious laryngo-tracheitis, whereas the older birds seem to be immune.' Other diseases found are fowl cholera, typhoid, tuberculosis, emaciation, limberneck, and paralysis. Ante-mortem rejections are also made for dropsy, bruises, fractures, toxemia, and moribund conditions. Out of about 35,000,000 birds examined in the dressed poultry inspection service, approximately 1,000,000 have been rejected as unfit for food. These conditions were distributed as follows: tuberculosis, 64 percent; decomposition, 15 per-cent; septicemia, 7 percent; emaciation, 31/2 percent; and miscellaneous pathological conditions, 10 percent.

Tuberculosis in poultry is caused by the organism Mycobacterium tuberculosis avium. This microbe is acid-fast and similar in other respects to the organism causative of human and bovine forms of tuberculosis. Avian tuberculosis is widespread in the domestic fowl, affecting 2 to 3 percent of the birds and running heavier in the northern central states. The disease is not so prevalent among cocks and well-fattened first-grade fowl, but is very heavy in third-grade old fowl. The organs most frequently involved are the liver, spleen, and intestines. The absence of lymph nodes in the chicken allows the tubercle bacilli to pass directly from the lymphatics into the general circulation, so that the organism can be cultured from normally appearing tissues without other signs of the disease." This fact, so different from the situation in bovine and swine tuberculosis, renders inadvisable any attempt to pass fowl for food when they have tuberculosis in any degree.

Numerous writers and investigators have stated that the disease is transmissible to man. Feldman has critically reviewed 37 re-ported instances in which avian tubercle bacilli were claimed to be the causative agents, and finds only 13 which gave convincing evidence of this etiology (although it is possible that some of the others would have been added to this number if the published data had been more explicit and detailed). In view of the widespread prevalence of the disease and the frequency of man's exposure, it seems that human beings must be strongly resistant to infection by this organism. How-ever, it is clear that a potential hazard does exist for the susceptible person. Possible sources of infection are undercooked poultry meat, raw vegetables fertilized with chicken manure, and possibly tuberculous eggs (see page 312).

Cooked poultry and its products have been incriminated in numerous outbreaks of gastrointestinal illness. Usually soups, stews, and salads have been involved because they constitute excellent culture media for microorganic growth, especially when these foods are left-over portions which are not kept refrigerated. A typical case is re-ported by Ilsley where a left-over portion of chicken was consumed by a group of students who became acutely ill within 6 hours after eating. The symptoms simulated those caused by organisms of the paratyphoid-enteritidis group. Samples of the chicken yielded Proteus vulgaris (Bacillus proteus), together with streptococci and colon bacilli. Proteus vulgaris was found in samples of vomitus and feces from the ill students, and the culture was pathogenic for guinea pigs.

Duck sickness. Duck sickness is the name popularly given to an epizootic involving ducks and other wild migratory birds found to be suffering from a form of botulism. This disease is caused by a toxin produced by a common saprophytic and anaerobic bacterium, Clostridium botulinum, type C. This organism is not only found in much of the bird food, but also occurs in the mud and even the water of small pools. In spite of the fact that, in the earlier days, birds dying of this disease were shot and sold to humans for food, there is no recorded instance of human beings having contracted the disease. Even those persons who prefer their game rare and a bit "high" have not been reported as suffering from the poisoning. Incidentally, this is circumstantial evidence of the relative immunity of man to oral doses of type C.

Decomposition. Poultry can be stored for 9 to 12 months without loss of flavor appreciable to the average consumer. Experienced poultrymen can detect a slightly bitter taste in the meat near the bone after 6 months' storage. A few months later, the bones begin to darken and the flesh loses some of its flavor. Poultry that is dry-picked or dry-thawed keeps better than water-treated stock. The quality of winter-produced fresh poultry is usually not so good as that of properly packed frozen poultry.

The tissues of poultry are subject to the same types of deterioration as those which occur in other meat. The musculature breaks down into various nitrogenous compounds and ammonia, and the fat splits off fatty acids which are accompanied by more or less rancidity. The work of Pennington 4 shows that these changes are an excellent index of the progress of the general deterioration of the flesh and that they are more delicate than organoleptic examination. Cold storage retards these changes so effectively that properly prepared poultry may be cold stored with such slight deterioration and alteration that, as Heitz states,' the most experienced poultryman would have difficulty in detecting by tasting any difference between fresh-killed poultry and that which had been stored for 5 or 6 months and then properly thawed. Some of the popular prejudice against cold-storage poultry rests on abuses which obtained in the earlier days before the proper technology had been worked out. Inasmuch as the flavor and texture of strictly fresh poultry produced in the winter and early spring months are inferior to those of the summer and fall, the proper handling and cold storing of the summer stock produces a higher-quality product for winter consumption than the fresh winter stock.

Storage poultry has been found to have undergone less deterioration after having been frozen for 8 months than fresh-dressed chicken that has been held in the housewife's icebox for 2 days.' Even after 12 months in the freezer, the deterioration is frequently less than that which has occurred in fresh-dressed chicken which has gone promptly from the producer to the consumer but which has not been kept constantly at a temperature below 40° F.

Frozen poultry is protected by refrigeration from deteriorative changes caused by bacteria, but when it is thawed, microbic action proceeds rapidly. It is better for the consumer to buy frozen poultry in frozen condition and thaw it immediately before cooking. This practice has the advantage that the food is protected from the uncertain amount of deterioration that may have set in if the dealer had defrosted the bird at an indeterminate prior time, or had soaked the bird in water. Furthermore, there is the added convenience of being able to keep the food in its frozen condition in the refrigerator until ready for cooking.

CONTROL MEASURES

Standards. The only standard or definition for poultry adopted in enforcing the Food and Drugs Act is the following:

Flesh. Any edible part of the striated muscle of an animal. The term "animal," as herein used, indicates a mammal, a fowl, a fish, a crustacean, a mollusk, or any other animal used as a source of food 17

However, tentative standards and grades have been proposed by the Bureau of Agricultural Economics for live poultry, dressed chickens, dressed and drawn broilers, fryers, and roasters, for dressed ducks, geese, guineas, squabs, and turkeys.

Poultry inspection. In connection with the grading service of the U. S. Bureau of Agricultural Economics for certifying the class, quality, and condition of perishable farm products, the division of dairy and poultry products has established a federal inspection service for live and dressed poultry, both ante- and post-mortem, under the direction of veterinarians.' Rules and regulations have been issued for the guidance of inspectors and for applicants. This service is not mandatory but entirely voluntary, and is provisional on the payment

CONTROL MEASURES 301 of the costs and compliance with the regulations by the applicants. Inspectors examine live poultry to reject diseased birds and to prevent

fraudulent practices—such as selling birds which are overcropped with feed, or water fowl with wet plumage. Coops in which diseased poultry was shipped are marked for identification and sent to the coop company's yards for cleaning and disinfecting before being used again. Infected railroad cars are placarded, and cleaned and disinfected under the direction of an inspector from the U. S. Bureau of Animal Industry. Service is also furnished to packers of dressed poultry and manufacturers of poultry products.

Supervisory procedure. Although poultry has not been incriminated as an important factor in the transmission of infectious diseases to man, the wide prevalence of avian tuberculosis, as well as the findings of the federal poultry inspection service, demonstrate the great extent to which diseased fowl are consumed by the unsuspecting public. No person would willingly eat a diseased bird, even though it were thoroughly cooked. Official inspection of poultry is warranted as fully as the regular meat-inspection service. A public demand for sound poultry would furnish the incentive to eradicate avian tuberculosis.

Other poultry diseases should not be disregarded. Ante-mortem and post-mortem inspection should eliminate all diseased birds. Birds should be dressed in plenty of light so that the operators themselves can see what to discard. Ample supplies of clean water should be available to wash the carcasses free from intestinal contamination. The premises should be kept clean, and free from feathers, blood, and offal of all kinds. Hot water should be available for scalding all equipment.

The City of Baltimore has adopted regulations covering the operations of poultry slaughter houses, and embracing the following provisions :

Special screened cesspool, directly connected to the sanitary sewer, and screened to prevent entry of feathers.

Tin box, with metal funnel-shaped compartments for bleeding the poultry, and drained to cesspool.

Funnels to be washed out frequently during operations to remove adhering blood.

Separate room for picking poultry.

Special covered metallic receptacles for feathers.

No wooden receptacles allowed.

Cleaning of premises required within 1/2 hour after completion of work. No slaughtering allowed in cellars.

Floor must be made of cement or hard-surfaced materials and properly pitched to drains.

Walls and ceiling painted with a light-colored, oil-base paint. Running water installed in killing room.

Wash bowl with running water, connected to sewer. Ventilation equivalent to window and door in opposite walls.

When poultry is offered for sale, it should be protected from handling by the public. Screening should protect it from flies. Thawed birds should not be allowed to lie in dirty water in their shipping containers, nor otherwise be exposed to insanitation and lack of refrigeration.

REFERENCES

1. R. R. SLOCUM, U. S. Dept. Agr. Farmer's Bul. 1377, 1936.

2. T. W. HErTZ, U. S. Dept. Agr. Circular 73, 1929.

3. L. D. IvEs, N. J. Pub. Health News, 18, 160 (1934).

4. M. E. PENNINGTON, U. S. Dept. Agr. Bureau of Chemistry Circular 70, 1911.

5. The Poultry Industry of the United States, Supplement to the Exhibit of

the United States at the 4th World's Poultry Congress, London, 1930.

6. T. W. HEITZ, U. S. Dept. Agr. Farmer's Bul. 1694, 1934.

7. W. O. ATWATER and A. P. BRYANT, U. S. Dept. Agr. Office Exp. Sta. Bul.

28, revised, 1906.

8. W. H. SEBRELL, G. A. WHEELER, and D. J. HUNT, Pub. Health Repts., 50, 1333 (1935).

9. H. C. SHERMAN, Food Products, Macmillan Co., New York, 3d ed., 1933.

10. E. P. DANIEL and H. E. MUNSELL, U. S. Dept. Agr. Miscel. Pub. 275, 1937.

11. B. A. GALLAGHER, U. S. Dept. Agr. Farmer's Bul. 1200, 1931; E. LASH, U. S. Dept. Agr. Leaflet 102, 1933.

12. W. H. FELDMAN, Avian Tuberculosis Infections, Williams and Wilkins Co., Baltimore, Md., 1939.

13. E. O. JORDAN, Food Poisoning and Food-borne Infection, University of Chicago Press, Chicago, Ill., 2nd ed., 1931, p. 124.

14. M. L. ILSLEY, J. Am. Med. Assoc., 90, 292 (1928).

15. E. R. KALMBACH, U. S. Dept. Agr. Tech. Bul. 411, 1934.

16. A. F. SHGSHIN, Proc. Sci. Inst. Vitamin Research (U. S. S. R.), 1, No. 1, 3 (1936), from Chem. Abs., 30, 6466 (1936).

17. Service and Regulatory Announcements, U. S. Food and Drug Administration, Food and Drug 2, 5th revision, 1936.

18. Tentative Standards and Grades for Live and Dressed Poultry, U. S. Bur. Agr. Economics.

19. Service and Regulatory Announcements, U. S. Bur. Agr. Economics, 137, December, 1932.

20. Regulations Governing the Killing of Fowl and Maintenance of Places for Their Slaughter, Commissioner of Health, Baltimore, Md., Oct. 5, 1928.

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