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Poultry farming is the form of
animal husbandry Animal husbandry is the branch of agriculture concerned with animals that are raised for meat, fibre, milk, or other products. It includes day-to-day care, selective breeding, and the raising of livestock. Husbandry has a long history, startin ...
which raises
domesticated birds This page gives a list of domesticated animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includ ...
such as chickens, ducks, turkeys and geese to produce meat or
eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion chickens are killed for consumption annually. Chickens raised for eggs are known as layers, while chickens raised for meat are called broilers. In the United States, the national organization overseeing poultry production is the Food and Drug Administration (FDA). In the UK, the national organisation is the
Department for Environment, Food and Rural Affairs The Department for Environment, Food and Rural Affairs (Defra) is a department of His Majesty's Government responsible for environmental protection, food production and standards, agriculture, fisheries and rural communities in the United K ...
(Defra).


Intensive and alternative

According to the World Watch Institute, 74 percent of the world's poultry meat, and 68 percent of eggs are produced intensively.''State of the World 2006'' World "atch Institute, p. 26 One alternative to intensive poultry farming is
free-range Free range denotes a method of farming husbandry where the animals, for at least part of the day, can roam freely outdoors, rather than being confined in an enclosure for 24 hours each day. On many farms, the outdoors ranging area is fenced, ...
farming using lower stocking densities. Poultry producers routinely use nationally approved medications, such as antibiotics, in feed or drinking water, to treat disease or to prevent disease outbreaks. Some FDA-approved medications are also approved for improved feed utilization.


Chicken coop

A chicken coop or hen house is a structure where chickens or other
fowl Fowl are birds belonging to one of two biological orders, namely the gamefowl or landfowl (Galliformes) and the waterfowl (Anseriformes). Anatomical and molecular similarities suggest these two groups are close evolutionary relatives; together ...
are kept safe and secure. There may be nest boxes and perches in the house. There is a long-standing controversy over the basic need for a chicken coop. One philosophy, known as the "fresh air school" is that chickens are mostly hardy but can be brought low by confinement, poor air quality and darkness, hence the need for a highly ventilated or open-sided coop with conditions more like the outdoors, even in winter. However, others who keep chickens believe they are prone to illness in outdoor weather and need a controlled-environment coop. This has led to two housing designs for chickens: fresh-air houses with wide openings and nothing more than wire mesh between chickens and the weather (even in Northern winters), or closed houses with doors, windows and hatches which can shut off most ventilation.


Egg-laying chickens

Commercial hens usually begin laying eggs at 16–21 weeks of age, although production gradually declines soon after from approximately 25 weeks of age. This means that in many countries, by approximately 72 weeks of age, flocks are considered economically unviable and are slaughtered after approximately 12 months of egg production, although chickens will naturally live for 6 or more years. In some countries, hens are force moulted to re-invigorate egg-laying. Environmental conditions are often automatically controlled in egg-laying systems. For example, the duration of the light phase is initially increased to prompt the beginning of egg-laying at 16–20 weeks of age and then mimics summer day length which stimulates the hens to continue laying eggs all year round; normally, egg production occurs only in the warmer months. Some commercial breeds of hen can produce over 300 eggs a year.


Free-range

Free-range poultry farming allows chickens to roam freely for a period of the day, although they are usually confined in sheds at night to protect them from predators or kept indoors if the weather is particularly bad. In the UK, the
Department for Environment, Food and Rural Affairs The Department for Environment, Food and Rural Affairs (Defra) is a department of His Majesty's Government responsible for environmental protection, food production and standards, agriculture, fisheries and rural communities in the United K ...
(Defra) states that a free-range chicken must have day-time access to open-air runs during at least half of its life. Unlike in the United States, this definition also applies to free-range egg-laying hens. The European Union regulates marketing standards for egg farming which specifies a minimum condition for free-range eggs that "hens have continuous daytime access to open air runs, except in the case of temporary restrictions imposed by veterinary authorities". The RSPCA "Welfare standards for laying hens and pullets" indicates that the stocking rate must not exceed 1,000 birds per hectare (10 m2 per hen) of range available and a minimum area of overhead shade/shelter of 8 m2 per 1,000 hens must be provided. Free-range farming of egg-laying hens is increasing its share of the market. Defra figures indicate that 45% of eggs produced in the UK throughout 2010 were free range, 5% were produced in barn systems and 50% from cages. This compares with 41% being free range in 2009. Suitable land requires adequate drainage to minimise worms and coccidial oocysts, suitable protection from prevailing winds, good ventilation, access and protection from predators. Excess heat, cold or damp can have a harmful effect on the animals and their productivity. Free range farmers have less control than farmers using cages in what food their chickens eat, which can lead to unreliable productivity, though supplementary feeding reduces this uncertainty. In some farms, the manure from free range poultry can be used to benefit crops. The benefits of free range poultry farming for laying hens include opportunities for natural behaviours such as pecking, scratching, foraging and exercise outdoors. Both intensive and free-range farming have animal welfare concerns.
Cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is well documented, bo ...
,
feather pecking Feather pecking is a behavioural problem that occurs most frequently amongst domestic hens reared for egg production,Huber-Eicher, B. and Sebo, F. 2001. The prevalence of feather pecking and development in commercial flocks of laying hens. Applie ...
and
vent pecking Vent pecking is an abnormal behaviour of birds performed primarily by commercial egg-laying hens. It is characterised by pecking damage to the cloaca, the surrounding skin and underlying tissue.Sherwin, C.M., (2010). The welfare and ethical as ...
can be common, prompting some farmers to use beak trimming as a preventative measure, although reducing stocking rates would eliminate these problems. Diseases can be common and the animals are vulnerable to predators. Barn systems have been found to have the worst bird welfare. In South-East Asia, a lack of disease control in free range farming has been associated with outbreaks of
Avian influenza Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds.'Free-range farming and avian flu in Asia''
retrieved July 6, 2007


Free-run

Instead of keeping them in cages, free-run laying hens roam freely within an enclosed barn. This type of housing also provides enrichment for the hens, including nesting boxes and perches that are often located along the floor of the barn. Many believe that this type of housing is better for the bird than any caging system, but it has its disadvantages, too. Due to the increase in activity of the birds, dust levels tend to elevate and the air quality decreases. When air quality drops, so does production as this compromises the health and welfare of both birds and their caretakers.


Organic

In organic egg-laying systems, chickens are also free-range. Organic systems are based upon restrictions on the routine use of synthetic yolk colourants, in-feed or in-water medications, other food additives and synthetic amino acids, and a lower stocking density and smaller group sizes. The
Soil Association The Soil Association is a British registered charity. The organisation activities include campaigning – against intensive farming, for local purchasing and public education on nutrition – and certification of organic foods. It was establis ...
standards used to certify organic flocks in the UK, indicate a maximum outdoors stocking density of 1,000 birds per hectare and a maximum of 2,000 hens in each poultry house. In the UK, organic laying hens are not routinely beak-trimmed.


Yarding

While often confused with free range farming, yarding is actually a separate method by which a hutch and fenced-off area outside are combined when farming poultry. The distinction is that free-range poultry are either totally unfenced, or the fence is so distant that it has little influence on their freedom of movement. Yarding is a common technique used by small farms in the Northeastern U.S. The birds are released daily from hutches or coops. The hens usually lay eggs either on the floor of the coop or in baskets if provided by the farmer. This husbandry technique can be complicated if used with roosters, mostly because of their aggressive behavior.


Battery cage

The majority of hens in many countries are housed in
battery cage Battery cages are a housing system used for various animal production methods, but primarily for egg-laying hens. The name arises from the arrangement of rows and columns of identical cages connected together, in a unit, as in an artillery bat ...
s, although the European Union Council Directive 1999/74/EC has banned the conventional battery cage in EU states from January 2012. As of April 1, 2017, no new battery cages are able to be installed in Canada. Farmers must move towards enriched housing or use a cage-free system. In 2016, the Egg Farmers of Canada announced that the country's egg farmers will be transitioning away from conventional hen housing systems (battery cages) and have no conventional caging left by 2036. These are small cages, usually made of metal in modern systems, housing 3 to 8 hens. The walls are made of either solid metal or mesh, and the floor is sloped wire mesh to allow the feces to drop through and eggs to roll onto an egg-collecting conveyor belt. Water is usually provided by overhead nipple systems, and food in a trough along the front of the cage replenished at regular intervals by a mechanical system. Battery cages are arranged in long rows as multiple tiers, often with cages back-to-back (hence the term). Within a single barn, there may be several floors containing battery cages meaning that a single shed may contain many tens of thousands of hens. Light intensity is often kept low (e.g. 10 lux) to reduce feather pecking and vent pecking. Benefits of battery cages include easier care for the birds, floor-laid eggs (which are expensive to collect) are eliminated, eggs are cleaner, capture at the end of lay is expedited, generally less feed is required to produce eggs, broodiness is eliminated, more hens may be housed in a given house floor space, internal parasites are more easily treated, and labor requirements are generally much reduced. In farms using cages for egg production, there are more birds per unit area; this allows for greater productivity and lower food costs.VEG
''Laying hens, free range and bird flu''
retrieved July 6, 2007
Floor space ranges upwards from 300 cm2 per hen. EU standards in 2003 called for at least 550 cm2 per hen. In the US, the current recommendation by the United Egg Producers is 67 to 86 in2 (430 to 560 cm2) per bird. The space available to battery hens has often been described as less than the size of a piece of A4 paper (623 cm2). Animal welfare scientists have been critical of battery cages because they do not provide hens with sufficient space to stand, walk, flap their wings, perch, or make a nest, and it is widely considered that hens suffer through boredom and frustration through being unable to perform these behaviours. This can lead to a wide range of abnormal behaviours, some of which are injurious to the hens or their cagemates.


Furnished cage

In 1999, the European Union Council Directive 1999/74/EC banned conventional battery cages for laying hens throughout the European Union from January 1, 2012; they were banned previously in other countries including Switzerland. In response to these bans, development of prototype commercial furnished cage systems began in the 1980s. Furnished cages, sometimes called 'enriched' or 'modified' cages, are cages for egg-laying hens which have been designed to allow the hens to perform their "natural behaviors" whilst retaining their economic and husbandry advantages, and also provide some of the welfare advantages of non-cage systems. Many design features of furnished cages have been incorporated because research in animal welfare science has shown them to be of benefit to the hens. In the UK, the Defra "Code for the Welfare of Laying Hens" states furnished cages should provide at least 750 cm2 of cage area per hen, 600 cm2 of which should be usable; the height of the cage other than that above the usable area should be at least 20 cm at every point and no cage should have a total area that is less than 2000 cm2. In addition, furnished cages should provide a nest, litter such that pecking and scratching are possible, appropriate perches allowing at least 15 cm per hen, a claw-shortening device, and a feed trough which may be used without restriction providing 12 cm per hen. Furnished cages (Enriched) give the hens more space than the conventional battery cages, so that each bird may spread their wings without touching one another if desired. Enrichment such as nest boxes, perches, and dust baths are also provided so that the birds may carry out their natural behaviors such as nesting, roosting, and scratching as though they were outdoors. Enrichment of laying hen cages ultimately results in better bone quality. This is a result of the increased activity in the hens from the additional space and enrichment provided in the furnished housing system. Although the enriched housing system has its advantages such as reduced aggression towards one another and cleaner eggs, modern egg laying breeds often suffer from osteoporosis which results in the chicken's skeletal system being weakened. During egg production, large amounts of calcium are transferred from bones to create egg-shell. Although dietary calcium levels are adequate, absorption of dietary calcium is not always sufficient, given the intensity of production, to fully replenish bone calcium. This can lead to increases in bone breakages, particularly when the hens are being removed from cages at the end of laying. Osteoporosis may be prevented by free range and cage-free housing systems, as they have shown to have a beneficial impact on the skeletal system of the hens compared to those housed in caged systems. Countries such as Austria, Belgium or Germany are planning to ban furnished cages until 2025 additionally to the already banned conventional cages.


Meat-producing chickens – husbandry systems


Indoor broilers

Meat chickens, commonly called
broilers A broiler is any chicken (''Gallus gallus domesticus'') that is bred and raised specifically for meat production. Most commercial broilers reach slaughter weight between four and six weeks of age, although slower growing breeds reach slaughte ...
, are floor-raised on litter such as wood shavings, peanut shells, and rice hulls, indoors in climate-controlled housing. Under modern farming methods, meat chickens reared indoors reach slaughter weight at 5 to 9 weeks of age, as they have been selectively bred to do so. In the first week of a broiler's life, it can grow up to 300 percent of its body size. A nine-week-old broiler averages over 9 pounds (4 kg) in body weight. At nine weeks, a hen will average around 7 pounds (3.2 kg) and a rooster will weigh around 12 pounds (5.5 kg), having a nine-pound (4 kg) average. Broilers are not raised in cages. They are raised in large, open structures known as grow out houses. A farmer receives the birds from the hatchery at one day old. A grow out consists of 5 to 9 weeks according to how big the kill plant wants the chickens to be. These houses are equipped with mechanical systems to deliver feed and water to the birds. They have ventilation systems and heaters that function as needed. The floor of the house is covered with bedding material consisting of wood chips, rice hulls, or peanut shells. In some cases they can be grown over dry litter or compost. Because dry bedding helps maintain flock health, most growout houses have enclosed watering systems ("nipple drinkers") which reduce spillage. Keeping birds inside a house protects them from predators such as hawks and foxes. Some houses are equipped with curtain walls, which can be rolled up in good weather to admit natural light and fresh air. Most growout houses built in recent years feature "tunnel ventilation," in which a bank of fans draws fresh air through the house. Traditionally, a flock of broilers consist of about 20,000 birds in a growout house that measures 400/500 feet long and 40/50 feet wide, thus providing about eight-tenths of a square foot per bird. The Council for Agricultural Science and Technology (CAST) states that the minimum space is one-half square foot per bird. More modern houses are often larger and contain more birds, but the floor space allotment still meets the needs of the birds. The larger the bird is grown the fewer chickens are put in each house, to give the bigger bird more space per square foot. Because broilers are relatively young and have not reached sexual maturity, they exhibit very little aggressive conduct. Chicken feed consists primarily of corn and soybean meal with the addition of essential vitamins and minerals. No hormones or steroids are allowed in raising chickens.


Issues with Indoor Husbandry

In intensive broiler sheds, the air can become highly polluted with ammonia from the droppings. In this case, a farmer must run more fans to bring in more clean fresh air. If not, this can damage the chickens' eyes and respiratory systems and can cause painful burns on their legs (called
hock burns Hock burns are marks found on the upper joints of chickens and other birds raised on broiler farms. These marks are where the ammonia from the waste of other birds has burned through the skin of the leg, leaving a mark. Many meat processors now remo ...
) as well as blisters on their feet. Broilers bred for fast growth have a high rate of developing leg deformities because their large breast muscles cause distortions on their developing legs and pelvis, leading to them often being unable to support their body weight. In cases where the chickens become crippled and can no longer walk, farmers have to go in and pull them out. Because of their difficulty moving, the chickens cannot change their environment to avoid heat, cold, or dirt as they would in natural conditions. The added weight and overcrowding also puts a strain on their hearts and lungs, possibly leading to
Ascites Ascites is the abnormal build-up of fluid in the abdomen. Technically, it is more than 25 ml of fluid in the peritoneal cavity, although volumes greater than one liter may occur. Symptoms may include increased abdominal size, increased weight, ab ...
. In the UK, up to 19 million broilers die in their sheds from heart failure each year. In a heat wave, if a power failure shuts down the ventilation, 20,000 chickens could die in a short period of time. In a good grow out, a farmer should sell between 92% and 96% of their flock, with a 1.80 to a 2.0
feed conversion ratio In animal husbandry, feed conversion ratio (FCR) or feed conversion rate is a ratio or rate measuring of the efficiency with which the bodies of livestock convert animal feed into the desired output. For dairy cows, for example, the output is mil ...
. After marketing the birds, the farmer must clean out and prepare for another flock. A farmer should average 4 to 5 grow outs a year.


Indoor with higher welfare

In a "higher welfare" system, chickens are kept indoors but with more space (around 14 to 16 birds per square metre). They have a richer environment for example with natural light or straw bales that encourage foraging and perching. The chickens grow more slowly and live for up to two weeks longer than intensively farmed birds. The benefits of higher welfare indoor systems are the reduced growth rate, less crowding and more opportunities for natural behaviour. One example of indoor production with higher welfare production is the Better Chicken Commitment standard.


Free-range broilers

Free-range broilers are reared under similar conditions to free-range egg-laying hens. The breeds grow more slowly than those used for indoor rearing and usually reach slaughter weight at approximately 8 weeks of age. In the EU, each chicken must have one square metre of outdoor space. The benefits of free-range poultry farming include opportunities for natural behaviours such as pecking, scratching, foraging and exercise outdoors. Because they grow slower and have opportunities for exercise, free-range broilers often have better leg and heart health.


Organic broilers

Organic broiler chickens are reared under similar conditions to free-range broilers but with restrictions on the routine use of in-feed or in-water medications, other food additives and synthetic amino acids. The breeds used are slower growing, more traditional breeds and typically reach slaughter weight at around 12 weeks of age. They have a larger space allowance outside (at least 2 square metres and sometimes up to 10 square metres per bird). The Soil Association standards indicate a maximum outdoors stocking density of 2,500 birds per hectare and a maximum of 1,000 broilers per poultry house.


Issues


Humane treatment

Animal welfare Animal welfare is the well-being of non-human animals. Formal standards of animal welfare vary between contexts, but are debated mostly by animal welfare groups, legislators, and academics. Animal welfare science uses measures such as longevity, ...
groups have frequently criticized the poultry industry for engaging in practices which they assert to be inhumane. Many
animal rights Animal rights is the philosophy according to which many or all sentient animals have moral worth that is independent of their utility for humans, and that their most basic interests—such as avoiding suffering—should be afforded the sam ...
advocates object to killing chickens for food, the "factory farm conditions" under which they are raised, methods of transport, and slaughter. Animal Outlook (formerly Compassion Over Killing) and other groups have repeatedly conducted undercover investigations at chicken farms and slaughterhouses which they allege confirm their claims of cruelty. A common practice among hatcheries for egg-laying hens is the culling of newly hatched male chicks since they do not lay eggs and do not grow fast enough to be profitable for meat. There are plans to more ethically destroy the eggs before the chicks are hatched, using "in-ovo" sex determination. Chickens are often stunned before slaughter using carbon dioxide or electric shock in a water bath. More humane methods that could be used are low atmospheric pressure stunning and
inert gas asphyxiation Inert gas asphyxiation is a form of asphyxiation which results from breathing a physiologically inert gas in the absence of oxygen, or a low amount of oxygen, rather than atmospheric air (which is composed largely of nitrogen and oxygen). Example ...
.


Beak trimming

Laying hens are routinely beak-trimmed at 1 day of age to reduce the damaging effects of aggression,
feather pecking Feather pecking is a behavioural problem that occurs most frequently amongst domestic hens reared for egg production,Huber-Eicher, B. and Sebo, F. 2001. The prevalence of feather pecking and development in commercial flocks of laying hens. Applie ...
and cannibalism. Scientific studies have shown that beak trimming is likely to cause both acute and chronic pain.Breward, J., (1984). Cutaneous nociceptors in the chicken beak. Proceedings of the Journal of Physiology, London 346: 56 Severe beak trimming, or beak trimming birds at an older age, may cause chronic pain. Following beak trimming of older or adult hens, the
nociceptor A nociceptor ("pain receptor" from Latin ''nocere'' 'to harm or hurt') is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sens ...
s in the beak stump show abnormal patterns of neural discharge, indicating acute pain.Breward, J., (1985). ''An Electrophysiological Investigation of the Effects of Beak Trimming in the Domestic Fowl (''Gallus gallus domesticus'')''. Ph.D. thesis, University of Edinburgh.Gentle, M.J., (1986). Beak trimming in poultry. World's Poultry Science Journal', 42: 268–275
Neuromas A neuroma (; plural: neuromata or neuromas) is a growth or tumor of nerve tissue. Neuromas tend to be benign (i.e. not cancerous); many nerve tumors, including those that are commonly malignant, are nowadays referred to by other terms. Neuromas ...
, tangled masses of swollen regenerating axon sprouts,Devor, M. and Rappaport, Z.H., (1990). ''Pain Syndromes in Neurology''., edited by H.L. Fields, Butterworths, London, p. 47. are found in the healed stumps of birds beak trimmed at 5 weeks of age or older and in severely beak trimmed birds. Neuromas have been associated with
phantom pain Phantom pain is a perception that an individual experiences relating to a limb or an organ that is not physically part of the body, either because it was removed or was never there in the first place. However, phantom limb sensations can also oc ...
in human amputees and have therefore been linked to chronic pain in beak trimmed birds. If beak trimming is severe because of improper procedure or done in older birds, the neuromas will persist which suggests that beak trimmed older birds experience
chronic pain Chronic pain is classified as pain that lasts longer than three to six months. In medicine, the distinction between acute and chronic pain is sometimes determined by the amount of time since onset. Two commonly used markers are pain that continue ...
, although this has been debated. Beak-trimmed chicks initially peck less than non-trimmed chickens, which animal behavioralist
Temple Grandin Mary Temple Grandin (born August 29, 1947) is an American academic and animal behaviorist. She is a prominent proponent for the humane treatment of livestock for slaughter and the author of more than 60 scientific papers on animal behavior. Gra ...
attributes to guarding against pain. The animal rights activist, Peter Singer, claims this procedure is bad because beaks are sensitive, and the usual practice of trimming them without anaesthesia is considered inhumane by some. Some within the chicken industry claim that beak-trimming is not painful whereas others argue that the procedure causes chronic pain and discomfort, and decreases the ability to eat or drink.


Antibiotics

Antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
have been used in poultry farming in mass quantities since 1951, when the Food and Drug Administration (FDA) approved their use. Scientists had found that chickens fed an antibiotic residue grew 50 percent faster than controls. The chickens laid more eggs and experienced lower mortality and less illness. Upon this discovery, farmers transitioned from expensive animal proteins to comparatively inexpensive antibiotics and B12. Chickens were now reaching their market weight at a much faster rate and at a lower cost. With a growing population and greater demand on the farmers, antibiotics appeared to be an ideal and cost-effective way to increase the output of poultry. Since this discovery, antibiotics have been routinely used in poultry production, but more recently have been the topic of debate secondary to the fear of bacterial
antibiotic resistance Antimicrobial resistance (AMR) occurs when microbes evolve mechanisms that protect them from the effects of antimicrobials. All classes of microbes can evolve resistance. Fungi evolve antifungal resistance. Viruses evolve antiviral resistance. ...
.


Arsenic

Poultry feed can include
roxarsone Roxarsone is an organoarsenic compound that has been used in poultry production as a feed additive to increase weight gain and improve feed efficiency, and as a coccidiostat. As of June 2011, it was approved for chicken feed in the United States, ...
or nitarsone,
arsenical Arsenicals are chemical compounds that contain arsenic. In a military context, the term arsenical refer to toxic arsenic compounds that are used as chemical warfare agents. This include blister agents, blood agents and vomiting agents. Examples Bl ...
antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals a ...
drugs that also promote growth.
Roxarsone Roxarsone is an organoarsenic compound that has been used in poultry production as a feed additive to increase weight gain and improve feed efficiency, and as a coccidiostat. As of June 2011, it was approved for chicken feed in the United States, ...
was used as a broiler starter by about 70% of the broiler growers between 1995 and 2000. The drugs have generated controversy because it contains
arsenic Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, but ...
, which is highly toxic to humans. This arsenic could be transmitted through run-off from the poultry yards. A 2004 study by the U.S. magazine Consumer Reports reported "no detectable arsenic in our samples of muscle" but found "A few of our chicken-liver samples has an amount that according to EPA standards could cause neurological problems in a child who ate 2 ounces of cooked liver per week or in an adult who ate 5.5 ounces per week." The U.S. Food and Drug Administration (FDA), however, is the organization responsible for the regulation of foods in America, and all samples tested were "far less than the... amount allowed in a food product."


Growth hormones

Hormone use in poultry production is illegal in the United States. Similarly, no chicken meat for sale in Australia is fed hormones. Several scientific studies have documented the fact that chickens grow rapidly because they are bred to do so, not because of growth hormones.


''E. coli''

According to
Consumer Reports Consumer Reports (CR), formerly Consumers Union (CU), is an American nonprofit consumer organization dedicated to independent product testing, investigative journalism, consumer-oriented research, public education, and consumer advocacy. Founde ...
, "1.1 million or more Americans resickened each year by undercooked, tainted chicken." A USDA study discovered '' E. coli (Biotype I)'' in 99% of supermarket chicken, the result of chicken butchering not being a sterile process. However, the same study also shows that the strain of ''E. coli'' found was always a non-lethal form, and no chicken had any of the pathenogenic O157:H7 serotype. Many of these chickens, furthermore, had relatively low levels of contamination. Feces tend to leak from the carcass until the evisceration stage, and the evisceration stage itself gives an opportunity for the interior of the carcass to receive intestinal bacteria. (The skin of the carcass does as well, but the skin presents a better barrier to bacteria and reaches higher temperatures during cooking.) Before 1950, this was contained largely by not eviscerating the carcass at the time of butchering, deferring this until the time of retail sale or in the home. This gave the intestinal bacteria less opportunity to colonize the edible meat. The development of the "ready-to-cook broiler" in the 1950s added convenience while introducing risk, under the assumption that end-to-end refrigeration and thorough cooking would provide adequate protection. ''E. coli'' can be killed by proper cooking times, but there is still some risk associated with it, and its near-ubiquity in commercially farmed chicken is troubling to some. Irradiation has been proposed as a means of sterilizing chicken meat after butchering. The aerobic bacteria found in poultry housing can include not only ''E. coli'', but ''Staphylococcus'', ''Pseudomona'', ''Micrococcus'' and others as well. These contaminants can contribute to dust that often causes issues with the respiratory systems of both the poultry and humans working in the environment. If bacterial levels in the poultry drinking water reach high levels, it can result in bacterial diarrhoea which can lead to blood poisoning should the bacteria spread from the damaged intestines. ''Salmonella'' too can be stressful on poultry production. How it causes disease has been investigated in some detail.


Avian influenza

There is also a risk that crowded conditions in chicken farms will allow
avian influenza Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds.United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmonizi ...
press release states: "Governments, local authorities and international agencies need to take a greatly increased role in combating the role of factory-farming, commerce in live poultry, and wildlife markets which provide ideal conditions for the virus to spread and mutate into a more dangerous form..."


Dermatitis

Several dermatitis conditions are significant in chickens especially gangrenous dermatitis. GD is caused by ''
Clostridium septicum ''Clostridium septicum'' is a gram positive, spore forming, obligate anaerobic bacterium. ''Clostridium septicum'' can cause gas gangrene, but unlike other Clostridium species like ''Clostridium perfringens'', no trauma is necessary at the si ...
'', ''Clostridium perfringens'' type A, '' Clostridium sordellii'', ''
Clostridium novyi ''Clostridium novyi'' (oedematiens) a Gram-positive, endospore- forming, obligate anaerobic bacteria of the class Clostridia. It is ubiquitous, being found in the soil and faeces. It is pathogenic, causing a wide variety of diseases in man and a ...
'', '' Staphylococcus aureus'', ''
Staphylococcus xylosus ''Staphylococcus xylosus'' is a species of bacteria belonging to the genus ''Staphylococcus''. It is a Gram-positive bacterium that forms clusters of cells. Like most staphylococcal species, it is coagulase-negative and exists as a commensal on ...
'', ''
Staphylococcus epidermidis ''Staphylococcus epidermidis'' is a Gram-positive bacterium, and one of over 40 species belonging to the genus ''Staphylococcus''. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiot ...
'', ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
'', ''
Pasteurella multocida ''Pasteurella multocida'' is a Gram-negative, nonmotile, penicillin-sensitive coccobacillus of the family Pasteurellaceae. Strains of the species are currently classified into five serogroups (A, B, D, E, F) based on capsular composition and ...
'', '' Pseudomonas aeruginosa'', ''
Enterococcus faecalis ''Enterococcus faecalis'' – formerly classified as part of the group D ''Streptococcus'' system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans. Like other species in the genus ''Enterococcus'', ''E ...
'', ''
Proteus In Greek mythology, Proteus (; Ancient Greek: Πρωτεύς, ''Prōteus'') is an early prophetic sea-god or god of rivers and oceanic bodies of water, one of several deities whom Homer calls the "Old Man of the Sea" ''(hálios gérôn)''. ...
'' spp., ''
Bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacill ...
'' spp., ''
Erysipelothrix rhusiopathiae ''Erysipelothrix rhusiopathiae'' is a Gram-positive, catalase-negative, rod-shaped, non-spore-forming, nonacid-fast, nonmotile bacterium. Distributed worldwide, ''E. rhusiopathiae'' is primarily considered an animal pathogen, causing the dise ...
'', and ''Gallibacterium anatis'' var. ''haemolytica''. Beemer et al. 1970 finds ''
Rhodotorula ''Rhodotorula'' is a genus of pigmented yeasts, part of the division Basidiomycota. It is readily identifiable by distinctive orange/red colonies when grown on Sabouraud's dextrose agar (SDA). This distinctive color is the result of pigments ...
mucilaginosa'' to cause a dermatitis in chickens easily confused with GD.


Efficiency

Farming of chickens on an industrial scale relies largely on high protein feeds derived from soybeans; in the European Union the soybean dominates the protein supply for animal feed, and the poultry industry is the largest consumer of such feed. Two kilograms of grain must be fed to poultry to produce 1 kg of weight gain, much less than that required for pork or beef. However, for every gram of protein consumed, chickens yield only 0.33 g of edible protein.


Economic factors

Changes in
commodity prices In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them. The price of a co ...
for poultry feed have a direct effect on the cost of doing business in the poultry industry. For instance, a significant rise in the price of corn in the United States can put significant economic pressure on large industrial chicken farming operations.


Waste management, manure

Poultry production requires regular control of excrement, and in many parts of the world, production operations, especially larger operations, need to comply with environmental regulations and protections. Different from mammalian excrement, in poultry (and all birds) urine and feces are excreted as a combined manure, and the result is both wetter and higher in concentrated nitrogen. Waste can be managed wet, dry or by some combination. Wet management is particularly used in battery egg laying operations, where the waste is sluiced out with constantly or occasionally flowing water. Water is also used to clean the floors around nesting sites that are separate from open runs. Dry management particularly refers to dry litter such as sawdust that is removed as needed. Dry can also include open pasture where manure is absorbed by the existing soil and vegetation, but needs to be monitored dillegently so as to not overwhelm the ground capacity and lead to runoff and other pollution problems. Both liquid sluicings and dry litter are used as organic fertilizers, but the wet bulk of liquids manure is harder to ship and is often limited to more local use, while the latter is easier to distribute in bulk and in commercial packaging.


Mortality

Mortality is a daily consideration for poultry farmers, and the carcasses must be disposed of in order to limit the spread of disease and the prevalence of pests. There are a variety of methods of disposal, the most common being burial,
compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...
ing,
incineration Incineration is a waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-energy facilities. Incineration and other high ...
, and rendering. Environmental concerns surrounding each of these methods deal with nutrient pollution into the surrounding soil and groundwater – because of these concerns, in many countries and US states the practice of burial in pits is heavily regulated or disallowed. Farmers may construct their own facilities for composting, or purchase equipment to begin incineration or storage for rendering. Composting offers a safe and practical use for the organic material, while proper management of a composting site limits odor and presence of pests. Incineration offers a swifter disposal method, but uses fuel energy and thus brings varying costs. Rendering has the advantage of being handled off site, and the use of freezers can eliminate the spread of pathogens in storage awaiting pickup. Government organizations, like the USDA, may offer financial assistance to farmers looking to begin utilizing environmentally friendly mortality solutions.


Predation

In North American production the most common predators are: * the
coyote The coyote (''Canis latrans'') is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological n ...
* foxes, especially the red fox * the
bobcat The bobcat (''Lynx rufus''), also known as the red lynx, is a medium-sized cat native to North America. It ranges from southern Canada through most of the contiguous United States to Oaxaca in Mexico. It is listed as Least Concern on the I ...
* mustelids **
weasel Weasels are mammals of the genus ''Mustela'' of the family Mustelidae. The genus ''Mustela'' includes the least weasels, polecats, stoats, ferrets and European mink. Members of this genus are small, active predators, with long and slend ...
s, especially the least weasel and long-tailed weasel *
birds of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators h ...
** hawks, especially the red-tailed, red-shouldered, and
Cooper's hawk Cooper's hawk (''Accipiter cooperii'') is a medium-sized hawk native to the North American continent and found from southern Canada to Mexico. This species is a member of the genus ''Accipiter'', sometimes referred to as true hawks, which are f ...
** owls, especially the great horned owl * the
raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of ...
* the Virginia opossum * skunks * rodents * snakes, especially the
rat snake Rat snakes are members – along with kingsnakes, milk snakes, vine snakes and indigo snakes – of the subfamily Colubrinae of the family Colubridae. They are medium to large constrictors and are found throughout much of the Northern Hem ...
*
pet dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. D ...
s and
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
s


Worker health and safety

Poultry workers experience substantially higher rates of illness and injury than manufacturing workers do on average. For the year 2013, there were an estimated 1.59 cases of occupation-related illness per 100 full-time U.S. meat and poultry workers, compared to .36 for manufacturing workers overall. Injuries are associated with repetitive movements, awkward postures, and cold temperatures. High rates of
carpal tunnel syndrome Carpal tunnel syndrome (CTS) is the collection of symptoms and signs associated with median neuropathy at the carpal tunnel. Most CTS is related to idiopathic compression of the median nerve as it travels through the wrist at the carpal tunn ...
and other muscular and skeletal disorders are reported. Disinfectant chemicals and infectious bacteria are causes of respiratory illnesses, allergic reactions,
diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin wi ...
, and skin infections. Poultry housing has been shown to have adverse effects on the respiratory health of workers, ranging from a cough to
chronic bronchitis Bronchitis is inflammation of the bronchi (large and medium-sized airways) in the lungs that causes coughing. Bronchitis usually begins as an infection in the nose, ears, throat, or sinuses. The infection then makes its way down to the bronchi. ...
. Workers are exposed to concentrated airborne particulate matter (PM) and endotoxins (a harmful waste product of bacteria). In a conventional hen house a conveyor belt beneath the cages removes the manure. In a cage-free aviary system the manure coats the ground, resulting in the build-up of dust and bacteria over time. Eggs are often laid on the ground or under cages in the aviary housing, causing workers to come close to the floor and force dust and bacteria into the air, which they then inhale during egg collection. Oxfam America reports that huge industrialized poultry operations are under such pressure to maximize profits that workers are denied access to toilets.


World chicken population

The Food and Agriculture Organization of the
United Nations The United Nations (UN) is an intergovernmental organization whose stated purposes are to maintain international peace and security, develop friendly relations among nations, achieve international cooperation, and be a centre for harmonizi ...
estimated that in 2002 there were nearly sixteen billion chickens in the world. In 2008, the top countries with the highest number of chickens in the world was led by China with the largest at approx 4.6 billion, followed by USA with approx over 2 billion and then followed by Indonesia, Brazil and Mexico. In 2019, China had over 5.14 billion chickens, a higher amount than any other country in the world, followed by Indonesia with approx 3.7 billion chickens. The countries with the next-highest amounts were USA, Brazil, Pakistan, Iran, India, Mexico, Russia and Myanmar respectively. In 1950, the average American consumed 20 pounds (9 kg) of chicken per year, but 92.2 pounds (41.9 kg) in 2017. Additionally, in 1980 most chickens were sold whole, but by 2000 almost 90 percent of chickens were sold after being butchered into parts.


See also

* Chicken harvester * Environmental issues with agriculture * Henopause * Hy-Line International * Poultry farming in the United States


References


External links

* {{Authority control Animal husbandry Chickens Ducks Geese Livestock