Chicken in the United States is a cheap and readily available meat. It is packed in a variety of formats, from whole roasting chickens to selections of one particular cut, such as thighs or wings. Highly automated, large-scale chicken farming and processing complexes run by large corporations fuel the American chicken market. The development of so-called factory farming sharply reduced the price and increased the availability of chicken, when this method was introduced in the 1920s.


The ancestor of today's domestic chicken is the wild red jungle fowl Gallus gallus, native to India and Southeast Asia. The red jungle fowl was first domesticated apparently for use in religious rituals involving cockfighting. The domesticated bird spread west-ward from India to Greece, and was later introduced to Western Europe by invading Roman armies. By the Roman era, chickens were used as food, both for their meat and for their eggs. Romans commonly carried them on their ships, as a convenient source of fresh food.

The first European settlers in North America brought chickens with them. But until the twentieth century, there was no chicken industry as such in this country. Care of the chicken flock was for the most part considered work for women and children. At that time, a typical hen laid only 30 eggs a year, and farm wives sold their excess at market as supplemental income. Chicken meat was usually only plentiful in the early summer, when chickens that had hatched in the spring were big enough to eat. Because chicken husbandry was primarily women's work, only as an adjunct to the major farm production, distribution channels were limited. Whereas railroads were built to bring cattle from the West to waiting urban markets, no such effort was put into chicken production, and chicken was available in cities more or less sporadically, with large seasonal jumps in prices and amount of supply.

Several inventors perfected chicken incubators in the late nineteenth century. These machines could keep hundreds of eggs at a time warm, and so made possible commercial breeding of chicks. In the nineteenth century, breeding of chickens was mostly a hobby, with many poultry enthusiasts raising fabulously feathered chickens. Showy and colorful exotic breeds were the most popular; however, with the advent of mechanical incubators, poultry breeders began to breed birds with good egg-laying and meat production potential.

The first person in the United States to raise broiler chickens (chickens for meat) on a large scale strictly for profit was a Mrs. Wilmer Steele, of Ocean View, Delaware. In 1923, Mrs. Steele bought 500 chicks and sold the surviving 387 of them when they matured to 2 lb (0.9 kg). Her profit was enormous, and within just a few years, Delaware became the center of a thriving chicken industry. In 1926, the state produced around one million broiler chickens.

By 1934, it was raising about seven million chickens annually. In the 1930s, the National Poultry Improvement Plan, a federal-state cooperative mission, helped chicken farmers use scientific breeding principles to produce superior strains of birds. At this time, birds were first bred specifically for meat production. The important qualities of broiler chickens were rapid growth, white feathers (dark feathers left unsightly stubs), and meaty breasts and thighs. The advances in breeding made quite an impact: in 1900, a typical chick took 16 weeks to reach 2 lb (0.9 kg), which was considered frying weight. Today, a commercial broiler chicken lives only about six weeks, and weighs about 4 lb (1.8 kg) at slaughter.

Advances in nutrition were also important to the development of a commercial chicken industry. Chicken nutrition has actually been studied more, and is better understood, than human nutrition. The combined efforts of the feed industry, the U.S. Department of Agriculture, and agricultural scientists led to optimum feed. The ratio of feed necessary per pound of chicken meat has fallen through this century, making chicken ever cheaper to produce. By the 1950s, several large companies had integrated feed production with chicken farming and meat processing, so that only a few large corporations controlled a high percentage of the chicken produced in this country. These major producers each slaughter millions of chickens a week.

Commercial chicken

The production complex

Chicken production is typically carried out at so-called complexes. Each complex contains a feed mill, a hatchery, a processing plant, and chicken farms where the chicks are raised, usually in a 30-40 mi (48.3-64.4 km) radius from the processing plant. Contract farmers receive chicks from the hatchery, and house them in climate-controlled chicken houses. The houses are typically 400 x 50 ft (122 x 15.24 m), and hold up to 20,000 chickens. The interior is open, with no cages or partitions. When the chickens are old enough for slaughter, they are collected and shipped to the processing plant.

The hatchery

  • 1 Broiler chickens are bred especially for meatiness, quick growth, and weight gain. Most chickens used for meat in this country are a hybrid of Comish males and White Rock females. The hatchery houses a flock of thousands of chickens. The hatchery building is a large open space similar to the house where broilers are raised, except it contains many small houses set inside it, which look like miniature versions of the traditional chicken coop. When the hens are ready to lay, they seek shelter in the coop. The eggs are collected from the coops and taken to incubate. The breeder hens live for about 45 weeks, after which they are no longer considered productive. These "spent" hens are slaughtered and their meat is usually used for pet food or bought by food companies that use cooked, diced meat (such as in soups).


  • 2 The eggs are placed in large walk-in incubators. The eggs are kept warm and periodically rotated by machine. They begin to hatch in about 20 days. Shortly before hatching, the eggs are transferred to drawers. Many processors now inoculate chicks for diseases in ovo, that is, in the shell before they hatch. This is usually done three days before hatching. The chicks peck their way out of their shells when they are ready. For their first several days of life, the chicks are still absorbing nutrients from their yolk sacs, so they do not need food at this time. Trays of newly hatched chicks are wheeled on carts to an inoculation area, where they are sprayed with a mist of vaccine against common diseases. Some producers "debeak" the chicks at this point, which actually means clipping the sharp tip off the beak. This prevents the birds from damaging each other by pecking. This practice was discontinued at some large producers in the late 1990s, as for the most part the growing chicks are not overly aggressive, and debeaking was deemed costly and unnecessary. Next, the chicks are shipped to the nearby "grow-out" farms.

Growing out

  • 3 The chicks live in large houses which hold as many as 20,000 birds. These grow-out houses are kept at about 85° F (29.4° C) through heating and ventilation controls. The birds are not caged, and typically they are provided with approximately 0.8 sq ft per bird. The floor of the house is covered with a dry bedding material such as wood chips, rice hulls, or peanut shells. The birds are fed a diet of chicken feed, which is typically 70% corn, 20% soy, and 10% other ingredients such as vitamins and minerals. Broiler chickens in the United States are not
    Chicken processing begins at the hatchery where hens lay eggs. The eggs are collected and incubated until they begin to hatch in about 20 days. The chicks live in large, growout houses where they are fed a diet of chicken feed. After growout, the birds are conveyored through a stun cabinet. The mild electrical current in the water stuns or paralyses the birds. Next, the birds are conveyed to an automatic neck cutter. The carcasses hang until all the blood has drained and then they are defeathered. Next, they are washed, cleaned, and immersed in cooled, chlorinated water for 40-50 minutes.
    fed any steroids or hormones. Sick birds are treated with antibiotics or other medications. These birds then go through a withdrawal period before slaughter, to make sure no medication residue remains in their meat. The birds are usually watered through nipple drinkers, so that they don't spill and wet their bedding.


  • 4 The chicks live in the growing-out houses for about six weeks. Broiler chickens have been bred for excessive weight gain, especially in their breasts and thighs. At six weeks, the chicks usually weigh about 4 lb (1.8 kg), and are ready for slaughter. Collecting of the chickens is usually done at night. Though a variety of mechanical collectors have been developed, such as vacuum devices and plow-like chicken pushers, the simplest and most effective way to get the chickens crated for transport to the processing plant is to have farm employees enter the house and gather the birds by hand. The workers catch the birds and stuff them into cabinet-like boxes. The boxes are stacked, and a driver with a forklift picks them up and loads them onto a waiting truck. The boxed chickens are stacked in the truck and driven to the processing plant. The processing center of the chicken complex is generally no more than 30-40 mi (48.3-64.4 km) from the grow-out farm, so that the birds do not have to be driven an excessive distance.


  • 5 At the processing plant, workers take the birds from their boxes and hang them by their feet on a conveyor belt. In a typical process, the birds on the conveyor are first passed through a vat of electrified salt water called a stun cabinet. About 20 birds occupy the stun cabinet at one time, and they remain in the water for about seven seconds. The mild electrical current in the water stuns or paralyses the birds. Next, the birds are conveyed to an automatic neck cutter—rotating blades that sever the two carotid arteries. The birds' carcasses hang until all the blood has drained.

Defeathering and evisceration

  • 6 The carcasses are then briefly immersed in hot water to scald the skins. This makes removal of the feathers easier. The carcasses move to automatic feather pickers, which are moving rubber fingers that rub off most of the feathers. Then the carcasses are scalded a second time and run through another feather picker. Lastly, a specialized machine removes the wing feathers. The defeathered carcasses next pass to a washer, which scrubs the outside of the body. The feet and head are cut off, and the carcass is conveyed to the evisceration area. Next, the carcass is suspended in shackles by the feet and neck, cut open, and the viscera (internal organs) are removed. When the carcass is empty, it is washed again inside and out by a multiple-nozzled sprayer.

Chilling and cutting

  • 7 The cleaned carcasses are sent down a / chute and immersed in a "chiller" of cooled, chlorinated water for 40-50 minutes. The entire slaughter process takes only about an hour, and the bulk of that time is taken up by the chilling. The internal temperature of the chicken must be brought down to 40° F (4.4° C) or lower before further processing. The chilled carcasses are then passed to a cutting room, where workers cut them into parts, unless they are to be packaged whole. Some carcasses may be cooked and the cooked meat removed and diced for foods such as chicken pot pie or soups. Meat from backs, necks, and wings may be processed separately for sale in other meat products such as hot dogs or cold cuts. In whatever format, the meat is packaged by workers at the processing plant, loaded into cases, and stored in a temperature-controlled warehouse.

Quality Control

Quality control is a particularly important issue in poultry farming because the end product is raw meat, which has the potential to carry disease-causing microorganisms. To prevent diseases in the chickens themselves, the chicks are vaccinated for common avian diseases. Veterinarians visit the growing-out farms and tend to any sick birds. Corporations that contract with the growing-out farms also typically send a service technician out on a weekly visit to each farm to monitor conditions.

Quality control at chicken-processing plants is done by the company and also by inspectors from the U.S. Department of Agriculture. A USDA inspector is required to be in the plant whenever chickens are being slaughtered. The government inspector examines the birds both before and after slaughter for obvious signs of disease and for injury, such as broken wings. The meat from injured parts is not usable.

In a typical process, there are two critical control points where the company continually monitors conditions. There may be additional control points as well. The first critical control point is just before the cleaned carcass goes to the chiller. An inspector pulls carcasses at random and visually inspects them under bright light. No fecal matter is allowed on the carcass at this point. If any is found in the random check, the production line must be stopped and all the birds that have gone through the chiller since the last inspection must be rewashed and chilled. The second critical control point is when the birds come out of the chiller. The internal temperature of the carcass must be 40° F (4.4° C) or lower at this stage. Inspectors make random sample checks to verify internal temperatures. Though these are the most important control points, each plant designs its own quality control program, and inspectors may also periodically verify the temperature of the scalding water, check the automatic equipment, and whatever else the company deems necessary.

Until 1998, USDA inspectors at chicken processing plants were required to do only what is called an organaleptic test of the chickens before and after slaughter. This translates to looking and smelling; that is, inspectors verified that the birds were disease-free and healthy by looking them over and perhaps giving the carcass a quick sniff.

In 1998, the USDA instituted a new quality control program for all meat processors known as Hazard Analysis Critical Control Points, or HACCP. Under HACCP, in addition to the organaleptic method, inspectors are also required to take periodic microbiological tests to look for dangerous bacteria. The most problematic bacteria in chicken meat are salmonella. Though this organism is killed with proper cooking of the meat, it can cause illness if the consumer does not handle the meat properly. In the 1980s, 50% of all chicken in the United States was purported to be infected with salmonella. The industry altered its quality control procedures, and brought the incidence down to 16% in 1996, and to below 10% in 1998, according to the USDA. Under HACCP, chicken must be randomly tested for salmonella at the production plant, and the rate of infection must be lower than 20%. Also under HACCP, USDA inspectors have the authority to shut down plants that they deem dirty or unsafe. The plant is not allowed to re-open until it comes up with a plan for remedying the situation. Some incidents that caused chicken processing plants to be shut in 1998 included carcasses falling on the floor, rodent infestation of the facility, and most commonly, failure to prevent fecal contamination.


Many of the byproducts of chicken slaughter can be used. Chicken feet are removed at the processing plant because they are not considered edible in the United States. However, chicken feet are a delicacy in Asia, and so large amounts of them are exported. The feathers can be ground up and used as a protein supplement in animal feed. Substandard meat is also commonly sold to pet food makers. However, many chickens die before slaughter, either at the growing-out farm or en route to the processing plant. These birds are disposed of in landfills. Sick or deformed chicks are culled—taken from the flock and killed (usually by wringing the neck)—after hatching, and these bodies must also be disposed. Unused viscera and parts also produce waste in chicken processing.

A significant waste produced in chicken farming is the feces of the birds. Because the flocks are so large, with 20,000 birds typical for a broiler growing-out farm, the amount of feces is enormous. Decomposing poultry manure produces ammonia, an irritating gas that can cause disease and distress in poultry workers and in the chickens themselves if chicken houses are not adequately cleaned and ventilated. Flies are attracted to chicken manure, and large-scale broiler farming may cause an unwelcome increase in the fly population in surrounding areas. The odor associated with large-scale chicken farming can also be a problem for neighbors. Of more concern than odor is the threat to water quality by run-off from chicken farming. Some chicken manure is used as fertilizer for crops, and when it rains, excessive nitrogen and phosphorus are washed into nearby bodies of water. Outbreaks of a harmful bacteria in the Chesapeake Bay area in 1997 were blamed on water conditions caused by run-off from chicken farms. To control run-off, chicken producers may opt to alter the feed they give their broilers, adding enzymes that help breakdown some of the nutrients in the waste.

Where to Learn More


Davis, Karen. Prisoned Chickens, Poisoned Eggs Summertown, Tennessee: Book Publishing Company, 1996.

Smith, Page, and Daniel, Charles. The Chicken Book. Boston: Little, Brown, 1975.


Gordon, John Steele. "The Chicken Story." American Heritage (September 1996).

"Poultry Growers Unite to Address Waste Issue." New York Times (August 25, 1998).

Sharpe, Rochelle. "U.S. Shut 34 Meat and Poultry Plants in Quarter Due to Sanitation or Safety ."Wall Street Journal (May 8,1998).

Angela Woodward

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Jan 18, 2012 @ 4:04 am
this is a useful site for food safety specialist who are still studying in universities.i am a student in the university of swaziland and my programme is envirnmental health science and my speciality is food sanitation and technology.what are the proper prerequisites for HACCP implementation in poultry processing plant OR what the this that the plant have to have in place before implementing HACCP



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