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Factory farming involves raising livestock in confinement at high stocking density, where a farm operates as a business — a practice typical in industrial farming by agribusinesses. The main products of this industry are meat, milk and eggs for human consumption. There have been issues regarding whether factory farming is sustainable and ethical.
Confinement at high stocking density is one part of a systematic effort to produce the highest output at the lowest cost by relying on economies of scale, modern machinery, biotechnology, and global trade. Confinement at high stocking density requires antibiotics and pesticides to mitigate the spread of disease and pestilence exacerbated by these crowded living conditions. In addition, antibiotics are used to stimulate livestock growth by killing intestinal bacteria. There are differences in the way factory farming techniques are practiced around the world. There is a continuing debate over the benefits, risks and ethical questions of factory farming. The issues include the efficiency of food production; animal welfare; whether it is essential for feeding the growing global population; the environmental impact and the health risks.
People adopted more intensive methods between the 15th and 19th century. With this growth in production best characterized by the Agricultural Revolution, where improvements in farming techniques allowed for significantly improved yields, and supported the urbanization of the population during the Industrial Revolution.
Innovations in agriculture beginning in the late 19th century paralleled developments in mass production in other industries. The identification of nitrogen and phosphorus as critical factors in plant growth led to the manufacture of synthetic fertilizers, making possible more intensive types of agriculture.
The first animals to be factory farmed were chickens. The discovery of vitamins and their role in animal nutrition, in the first two decades of the 20th century, led to vitamin supplements, which allowed chickens to be raised indoors. The discovery of antibiotics and vaccines facilitated raising livestock in larger numbers by reducing disease. Chemicals developed for use in World War II gave rise to synthetic pesticides. Developments in shipping networks and technology have made long-distance distribution of agricultural produce feasible.
According to the BBC, factory farming in Britain began in 1947 when a new Agriculture Act granted subsidies to farmers to encourage greater output by introducing new technology, in order to reduce Britain's reliance on imported meat. The United Nations writes that "intensification of animal production was seen as a way of providing food security."
In 1960s North America, pigs and cows began to be raised on factory farms. This practice then spread to Western Europe. In Britain, the agriculture correspondent of The Guardian wrote in 1964:
Advocates of factory farming claim that factory farming has led to the betterment of housing, nutrition, and disease control over the last twenty years. From its American and West European heartland factory farming became globalised in the later years of the 20th century and is still expanding and replacing traditional practices of stock rearing in an increasing number of countries. In 1990 factory farming accounted for 30% of world meat production. By 2005 this had risen to 40%.
Nature of the practice
Agricultural production across the world doubled four times between 1820 and 1975 (1820 to 1920; 1920 to 1950; 1950 to 1965; and 1965 to 1975) to feed a global population of one billion human beings in 1800 and 6.5 billion in 2002.
During the same period, the number of people involved in farming dropped as the process became more automated. In the 1930s, 24 percent of the American population worked in agriculture compared to 1.5 percent in 2002; in 1940, each farm worker supplied 11 consumers, whereas in 2002, each worker supplied 90 consumers.
The number of farms has also decreased, and their ownerships are more concentrated. However, in the U.S. 766,350 producers participate in raising beef. The beef industry is segmented with the bulk of the producers participating in raising beef calves. Beef calves are generally raised in small herds, with over 90% of the herds having less than 100 head of cattle. Fewer producers participate in the finishing phase which often occurs in a feedlot, but nonetheless there are 82,170 feedlots in the United States. (NASS 2010; http://usda.mannlib.cornell.edu/usda/current/USCatSup/USCatSup-12-17-2010.pdf) The major concentration of the industry occurs at the slaughter and meat processing phase, with only four companies slaughtering and processing 81 percent of cows, 73 percent of sheep, 57 percent of pigs and 50 percent of chickens. This concentration at the slaughter phase is in large part due to regulator barriers that make it nearly impossible for small slaughter plants to be built, maintained or stay in business. Factory farming is no more beneficial to livestock producers than traditional farming because it contributes to the overproduction that drives down prices. Through “forward contracts” and “marketing agreements,” meatpackers are able to set the price of livestock long before they are ready for production. These strategies often cause farmers to lose money, as half of all U.S. family farming operations did in 2007. Many of the nation's livestock producers would like to market livestock directly to consumers but with limited USDA inspected slaughter facilities livestock grown locally can not typically be slaughtered and processed locally. In 1967, there were one million pig farms in America; as of 2002, there were 114,000, with 80 million pigs (out of 95 million) killed each year on factory farms as of 2002, according to the U.S. National Pork Producers Council. According to the Worldwatch Institute, 74 percent of the world's poultry, 43 percent of beef, and 68 percent of eggs are produced this way.
Europe has become increasingly skeptical of factory farming, after a series of diseases such as Bovine spongiform encephalopathy (BSE, "mad cow") and foot and mouth disease affected its agricultural industries, yet despite these outbreaks there are indications that the industrialized production of farm animals is set to increase globally. According to Denis Avery of the Hudson Institute, Asia increased its consumption of pork by 18 million tons in the 1990s. As of 1997, the world had a stock of 900 million pigs, which Avery predicts will rise to 2.5 billion pigs by 2050. He told the College of Natural Resources at the University of California, Berkeley that three billion pigs will thereafter be needed annually to meet demand.
Factory farms hold large numbers of animals, typically cows, pigs, turkeys, or chickens, often indoors, typically at high densities. The aim of the operation is to produce large quantities of meat, eggs, or milk at the lowest possible cost. Food is supplied in place, and a wide variety of artificial methods are employed to maintain animal health and improve production, such as the use of antimicrobial agents, vitamin supplements, and growth hormones. Physical restraints are used to control movement or actions regarded as undesirable. Breeding programs are used to produce animals more suited to the confined conditions and able to provide a consistent food product.
The distinctive characteristic of factory farms is the intense concentration of livestock. At one farm (Farm 2105) run by Carrolls Foods of North Carolina, the second-largest pig producer in the U.S., twenty pigs are kept per pen and each confinement building or "hog parlor" holds 25 pens. The company's chief executive officer, F.J. "Sonny" Faison, has said: "It's all a supply-and-demand price question … The meat business in this country is just about perfect, uncontrolled supply-and-demand free enterprise. And it continues to get more and more sophisticated, based on science. Only the least-cost producer survives in agriculture." Faison states:
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The large concentration of animals, animal waste, and the potential for dead animals in a small space poses ethical issues. It is recognized that some techniques used to sustain intensive agriculture can be cruel to animals. As awareness of the problems of intensive techniques has grown, there have been some efforts by governments and industry to remove inappropriate techniques.
In the UK, the Farm Animal Welfare Council was set up by the government to act as an independent advisor on animal welfare in 1979 and expresses its policy as five freedoms: from hunger & thirst; from discomfort; from pain, injury or disease; to express normal behavior; from fear and distress.
There are differences around the world as to which practices are accepted and there continue to be changes in regulations with animal welfare being a strong driver for increased regulation. For example, the EU is bringing in further regulation to set maximum stocking densities for meat chickens by 2010, where the UK Animal Welfare Minister commented, "The welfare of meat chickens is a major concern to people throughout the European Union. This agreement sends a strong message to the rest of the world that we care about animal welfare.”
Factory farming is greatly debated throughout Australia, with many people disagreeing with the methods and ways in which the animals in factory farms are treated. Animals are often under stress from being kept in confined spaces and will attack each other. In an effort to prevent injury leading to infection, their beaks, tails and teeth are removed. Many piglets will die of shock after having their teeth and tails removed. This is due to the fact that painkilling medicines are not used in these operations. Others say that factory farms are a great way to gain space, with animals such as chickens being kept in spaces smaller than an A4 page.
Less cruel methods of factory farming are still preferable. For example, in the UK, de-beaking of chickens is deprecated, but it is recognized that it is a method of last resort, seen as better than allowing vicious fighting and ultimately cannibalism. Between 60 and 70 percent of six million breeding sows in the U.S. are confined during pregnancy, and for most of their adult lives, in 2 ft (0.61 m) by 7 ft (2.1 m) gestation crates. According to pork producers and many veterinarians, sows will fight if housed in pens. The largest pork producer in the U.S. said in January 2007 that it will phase out gestation crates by 2017. They are being phased out in the European Union, with a ban effective in 2013 after the fourth week of pregnancy. With the evolution of factory farming, there has been a growing awareness of the issues amongst the wider public, not least due to the efforts of animal rights and welfare campaigners. As a result gestation crates, one of the more contentious practices, are the subject of laws in the U.S., Europe and around the world to phase out their use as a result of pressure to adopt less confined practices.
Human health impact
According to the U.S. Centers for Disease Control and Prevention (CDC), farms on which animals are intensively reared can cause adverse health reactions in farm workers. Workers may develop acute and chronic lung disease, musculoskeletal injuries, and may catch infections that transmit from animals to human beings (such as tuberculosis).
Pesticides are used to control organisms which are considered harmful and they save farmers money by preventing product losses to pests. In the US, about a quarter of pesticides used are used in houses, yards, parks, golf courses, and swimming pools and about 70% are used in agriculture. However, pesticides can make their way into consumers' bodies which can cause health problems. One source of this is bioaccumulation in animals raised on factory farms.
The CDC writes that chemical, bacterial, and viral compounds from animal waste may travel in the soil and water. Residents near such farms report problems such as unpleasant smell, flies and adverse health effects.
The CDC has identified a number of pollutants associated with the discharge of animal waste into rivers and lakes, and into the air. The use of antibiotics may create antibiotic-resistant pathogens; parasites, bacteria, and viruses may be spread; ammonia, nitrogen, and phosphorus can reduce oxygen in surface waters and contaminate drinking water; pesticides and hormones may cause hormone-related changes in fish; animal feed and feathers may stunt the growth of desirable plants in surface waters and provide nutrients to disease-causing micro-organisms; trace elements such as arsenic and copper, which are harmful to human health, may contaminate surface waters.
In the European Union, growth hormones are banned on the basis that there is no way of determining a safe level. The UK has stated that in the event of the EU raising the ban at some future date, to comply with a precautionary approach, it would only consider the introduction of specific hormones, proven on a case by case basis. In 1998, the European Union banned feeding animals antibiotics that were found to be valuable for human health. Furthermore, in 2006 the European Union banned all drugs for livestock that were used for growth promotion purposes. As a result of these bans, the levels of antibiotic resistance in animal products and within the human population showed a decrease.
The various techniques of factory farming have been associated with a number of European incidents where public health has been threatened or large numbers of animals have had to be slaughtered to deal with disease. Where disease breaks out, it may spread more quickly, not only due to the concentrations of animals, but because modern approaches tend to distribute animals more widely. The international trade in animal products increases the risk of global transmission of virulent diseases such as swine fever, BSE, foot and mouth and bird flu.
In the United States, the use of antibiotics in livestock is still prevalent. The FDA reports that 80 percent of all antibiotics sold in 2009 were administered to livestock animals, and that many of these antibiotics are identical or closely related to drugs used for treating illnesses in humans. Consequently, many of these drugs are losing their effectiveness on humans, and the total healthcare costs associated with drug-resistant bacterial infections in the United States are between $16.6 billion and $26 billion annually.
Methicillin-resistant Staphylococcus aureus (MRSA) has been identified in pigs and humans raising concerns about the role of pigs as reservoirs of MRSA for human infection. One study found that 20% of pig farmers in the United States and Canada in 2007 harbored MRSA. A second study revealed that 81% of Dutch pig farms had pigs with MRSA and 39% of animals at slaughter carried the bug were all of the infections were resistant to tetracycline and many were resistant to other antimicrobials. A more recent study found that MRSA ST398 isolates were less susceptible to tiamulin, an antimicrobial used in agriculture, than other MRSA or methicillin susceptible S. aureus. Cases of MRSA have increased in livestock animals. CC398 is a new clone of MRSA that has emerged in animals and is found in intensively reared production animals (primarily pigs, but also cattle and poultry), where it can be transmitted to humans. Although dangerous to humans, CC398 is often asymptomatic in food-producing animals.
A 2011 study reported that according to a nationwide study nearly half of the meat and poultry sold in U.S. grocery stores—47 percent—was contaminated with S. aureus, and more than half of those bacteria—52 percent—were resistant to at least three classes of antibiotics. Although Staph should be killed with proper cooking, it may still pose a risk to consumers through improper food handling and cross-contamination in the kitchen. The senior author of the study said, "The fact that drug-resistant S. aureus was so prevalent, and likely came from the food animals themselves, is troubling, and demands attention to how antibiotics are used in food-animal production today."
In April 2009, lawmakers in the Mexican state of Veracruz accused large-scale hog and poultry operations of being breeding grounds of a pandemic swine flu, although they did not present scientific evidence to support their claim. A swine flu which quickly killed more than 100 infected persons in that area, appears to have begun in the vicinity of a Smithfield subsidiary pig CAFO (concentrated animal feeding operation).
Animal health and welfare
Confinement and overcrowding of animals results in a lack of exercise and natural locomotory behavior, which weakens their bones and muscles. An intensive poultry farm provides the optimum conditions for viral mutation and transmission – thousands of birds crowded together in a closed, warm, and dusty environment is highly conducive to the transmission of a contagious disease. Selecting generations of birds for their faster growth rates and higher meat yields has left birds’ immune systems less able to cope with infections and there is a high degree of genetic uniformity in the population, making the spread of disease more likely. Further intensification of the industry has been suggested by some as the solution to avian flu, on the rationale that keeping birds indoors will prevent contamination. However, this relies on perfect, fail-safe biosecurity – and such measures are near impossible to implement. Movement between farms by people, materials, and vehicles poses a threat and breaches in biosecurity are possible. Intensive farming may be creating highly virulent avian flu strains. With the frequent flow of goods within and between countries, the potential for disease spread is high. Confinement and overcrowding of animals' environment presents the risk of contamination of the meat from viruses and bacteria. Feedlot animals reside in crowded conditions and often spend their time standing in their own waste. A dairy farm with 2,500 cows may produce as much waste as a city of 411,000 people, and unlike a city in which human waste ends up at a sewage treatment plant, livestock waste is not treated. As a result, feedlot animals have the potential of exposure to various viruses and bacteria via the manure and urine in their environment. Furthermore, the animals often have residual manure on their bodies when they go to slaughter.
Confinement at high stocking density requires antibiotics and pesticides to mitigate the spread of disease and pestilence exacerbated by these crowded living conditions. In addition, antibiotics are used to stimulate livestock growth by killing intestinal bacteria. According to a February 2011 FDA report, nearly 29 million pounds of antimicrobials were sold in 2009 for both therapeutic and non-therapeutic use for all farm animal species. The Union of Concerned Scientists estimates that 70% of that amount is for non-therapeutic use.
Animal welfare impacts of factory farming can include:
- Close confinement systems (cages, crates) or lifetime confinement in indoor sheds
- Discomfort and injuries caused by inappropriate flooring and housing
- Restriction or prevention of normal exercise and most of natural foraging or exploratory behaviour
- Restriction or prevention of natural maternal nesting behaviour
- Lack of daylight or fresh air and poor air quality in animal sheds
- Social stress and injuries caused by overcrowding
- Health problems caused by extreme selective breeding and management for fast growth and high productivity
- Reduced lifetime (longevity) of breeding animals (dairy cows, breeding sows)
- Fast-spreading infections encouraged by crowding and stress in intensive conditions
- Debeaking (beak trimming or shortening) in the poultry and egg industry to avoid pecking in overcrowded quarters
- Forced and over feeding (by inserting tubes into the throats of ducks) in the production of foie gras
- The feeling of being reduced to a small cog in a machine.
Concentrating large numbers of animals in factory farms is a major contribution to global environmental degradation, through the need to grow feed (often by intensive methods using excessive fertiliser and pesticides), pollution of water, soil and air by agrochemicals and manure waste, and use of limited resources (water, energy).
Livestock production is also particularly water-intensive in indoor, intensive systems. Eight percent of global human water use goes towards animal production, including water used to irrigate feed crops.
Industrial production of pigs and poultry is an important source of GHG emissions and is predicted to become more so. On intensive pig farms, the animals are generally kept on concrete with slats or grates for the manure to drain through. The manure is usually stored in slurry form (slurry is a liquid mixture of urine and feces). During storage on farm, slurry emits methane and when manure is spread on fields it emits nitrous oxide and causes nitrogen pollution of land and water. Poultry manure from factory farms emits high levels of nitrous oxide and ammonia.
Organic pig meat production has a lower global warming potential per kg than does intensive pig meat production. The energy input for free-range poultry meat and eggs is higher than for factory-farmed poultry meat and eggs, but GHG emissions are lower.
Poultry farming also has a high impact on the environment due to extreme excrement production by the chickens, which they are then forced to live in for the remainder of their lives.
Environmental impacts of factory farming can include:
- Deforestation for animal feed production
- Unsustainable pressure on land for production of high-protein/high-energy animal feed
- Pesticide, herbicide and fertilizer manufacture and use for feed production
- Unsustainable use of water for feed-crops, including groundwater extraction
- Pollution of soil, water and air by nitrogen and phosphorus from fertiliser used for feed-crops and from manure
- Land degradation (reduced fertility, soil compaction, increased salinity, desertification)
- Loss of biodiversity due to eutrophication, acidification, pesticides and herbicides
- Worldwide reduction of genetic diversity of livestock and loss of traditional breeds
- Species extinctions due to livestock-related habitat destruction (especially feed-cropping)
Small farmers are often absorbed into factory farm operations, acting as contract growers for the industrial facilities. In the case of poultry contract growers, farmers are required to make costly investments in construction of sheds to house the birds, buy required feed and drugs - often settling for slim profit margins, or even losses. Factory farm workers also cite the repetitive actions and high line speeds that are features of the large-scale slaughtering and processing facilities that characterize the factory farming poultry sectors, as causing injuries and illness to workers. Forced labor is another problem encountered in factory farming system. Greenpeace’s report  described a set of poor labor conditions at Roncador Farm in Mato Grosso, where workers are responsible for maintaining more than 100,000 cattle and 4,000 ha (9,000 ac) of soybeans:
"Working 16 hours a day, seven days a week, the laborers were forced to live in plastic shanties with no beds or sanitary provision. Water for washing, cooking and drinking came from a cattle watering hole and was stored in barrels previously used for diesel oil and lubricants. There was no opportunity to leave the farm. Goods had to be bought from the farm shop at extortionate prices, putting laborers into ever-increasing debt, which they would never be able to pay off—a form of slavery known as debt bondage." Even with laborers knowing this consciously, they have no choice but to abide to what they have due to the fact of their move from home, and fear of losing everything they currently have.
While federal and state labor laws are intended to protect all workers equally, many violations of these laws occur in the factory farms of the United States. Many factory farm workers are undocumented immigrants that farming businesses find ideal to hire because they are less likely to complain about low wages and hazardous working conditions. Using undocumented workers allows companies to easily replace them when a worker dies or gets injured. These illegal workers can also be easily persuaded to drop unfair labor charges when companies threaten to go to authorities regarding illegal immigration status.
Farmed animals and the law
In the United States, farmed animals are excluded by half of all state animal cruelty laws including the federal Animal Welfare Act. The 28 hour law, enacted in 1873 and amended in 1994 states that when animals are being transported for slaughter, the vehicle must stop every 28 hours and the animals must be let out for exercise, food, and water. The United States Department of Agriculture claims that the law does not apply to birds. The Humane Methods of Livestock Slaughter Act is similarly limited. Originally passed in 1958, the Act requires that livestock be stunned into unconsciousness prior to slaughter. This Act also excludes birds, who make up more than 90 percent of the animals slaughtered for food, as well as rabbits and fish. Individual states all have their own animal cruelty statutes; however many states have a provision to exempt standard agricultural practices.
Regulation of factory farming
In the United States there is a growing movement to mitigate the worst abuses by regulating factory farming. In Ohio animal welfare organizations reached a negotiated settlement with farm organizations while in California Proposition 2, Standards for Confining Farm Animals, an initiated law was approved by voters in 2008. Regulations have been enacted in other states and plans are underway for referendum and lobbying campaigns in other states.
An action plan has been proposed by the USDA in February 2009, called the Utilization of Manure and Other Agricultural and Industrial Byproducts. This program’s goal is to protect the environment and human and animal health by using manure in a safe and effective manner. In order for this to happen, several actions need to be taken and these four components include : • Improving the Usability of Manure Nutrients through More Effective Animal Nutrition and Management • Maximizing the Value of Manure through Improved Collection, Storage, and Treatment Options • Utilizing Manure in Integrated Farming Systems to Improve Profitability and Protect Soil, Water, and Air Quality • Using Manure and Other Agricultural Byproducts as a Renewable Energy Source
In 2012 Australia's largest supermarket chain, Coles, announced that as of January 1, 2013, they will stop selling company branded pork and eggs from animals kept in factory farms. The nation's other dominant supermarket chain, Woolworths, has already begun phasing out factory farmed animal products. All of Woolworth's house brand eggs are now cage-free, and by mid-2013 all of their pork will come from farmers who operate stall-free farms.
Aspects of factory farming
- Low monetary cost — Intensive agriculture tends to produce food that can be sold at lower cost to consumers. This is achieved by reducing land costs, management costs, and feed costs through government subsidized agricultural methods. However, critic Michael Pollan argues, "Cheap industrial food, the organic movement has argued, only seems cheap, because the real costs are charged to the environment (in the form of water and air pollution and depletion of the soil); to the public purse (in the form of subsidies to conventional commodity producers); and to the public health (in the cost of diabetes, obesity and cardiovascular disease), not to mention to the welfare of the farm- and food-factory workers and the well-being of the animals.
- Standardization — Factory farming methods permit increased consistency and control over product output. However, this results in less genetic diversity among animals, and weakened immune systems.
- Efficiency — Animals in confinement can be supervised more closely than free-ranging animals, and diseased animals can be treated faster.
- Economic contribution — The high input costs of agricultural operations result in a large influx and distribution of capital to a rural area from distant buyers rather than simply recirculating existing capital. A single dairy cow contributes over US$1,300 to a local rural economy each year, each beef cow over US$800, meat turkey US$14, and so on. As Pennsylvania Secretary of Agriculture Dennis Wolff states, "Research estimates that the annual economic impact per cow is US$13,737. In addition, each US$1 million increase in Pennsylvania milk sales creates 23 new jobs. This tells us that dairy farms are good for the state's economy."
- Food safety — Reducing number and diversity of agricultural production facilities may or may not make oversight and regulation of food quality easier. However, crowding and filthy conditions can make diseases like E.coli easily transferred between animals. Overuse of antibiotics can also result in the development of drug-resistant "superbugs".
- Animal health — Larger farms may or may not require greater resources to maintain a high level of animal health. Larger farms can potentially employ expert employees who devote their working hours to assessing animal health, a task which would be cost-prohibitive for most small farms. Larger farms may or may not be more able to make regular use of veterinarians and the resources of state and federal agricultural extension services. Industrial agriculture generally provides more mechanisms for the use of antibiotics to prevent and treat diseases than non-industrial agriculture. However, being tightly confined with crates and chains can result in bruises and cuts among animals. Also, feeding corn to cattle results in many conditions like acidosis, liver abscesses,
- Diseases – Intensive farming may make the evolution and spread of harmful diseases easier. Many communicable animal diseases spread rapidly through densely spaced populations of animals and crowding makes genetic reassortment more likely. However small family farms are more likely to introduce bird diseases and more frequent association with people into the mix, as happened in the recent 2009 flu pandemic Some evidence suggests that antibiotic use in agriculture has contributed to antibiotic resistance in humans.
- Pollution — Large quantities and concentrations of waste are produced. Lakes, rivers, and groundwater are at risk when animal waste is improperly recycled. Pollutant gases are also emitted. Concentrations of animals can produce unacceptable levels of foul smells as opposed to the tolerable odours of the countryside. In less intensive conditions, natural processes can break down potential pollutants. Large farms can maintain and operate sophisticated systems to control waste products. Smaller farms may or may not be less able to invest in the same standards of pollution control.
- Ethics — Cruelty to animals: Crowding, drugging, and performing surgery on animals. On some farms, chicks may be debeaked when very young, causing pain and shock. Confining hens and pigs in crates no larger than the animal itself may lead to physical problems such as osteoporosis and joint pain, and psychological problems including boredom, depression, and frustration, as shown by repetitive or self-destructive actions. Animal treatment is subject to welfare legislation, though there is not consensus on what is acceptable, and there is virtually no oversight by authorities.
- Destruction of biodiversity — A tendency towards using a monoculture of single adapted breeds in factory farming, both in arable and animal farming, gives uniform product designed for high yields, at the risk of increased susceptibility to disease. The loss of locally adapted breeds reduces the resilience of the agricultural system. The issue is not limited to factory farming and historically the problem is reflected in the rapid adoption of one or two strains of crops across a wide area as seen in the Irish potato famine of 1845 and the Bengal rice famine in 1942. The loss of the gene pool of domesticated animals limits the ability to adapt to future problems.
- Battery cage
- Cattle Health Initiative
- Concentrated Animal Feeding Operations
- Controlled-atmosphere killing
- Environmental vegetarianism
- Farm Sanctuary
- Food systems
- Gestation crate
- Humane Slaughter Act
- Intensive pig farming
- List of foodborne illness outbreaks
- Small-scale agriculture
- System of Rice Intensification
- Sources discussing "intensive farming", "intensive agriculture" or "factory farming":
- Fraser, David. Animal welfare and the intensification of animal production: An alternative interpretation, Food and Agriculture Organization of the United Nations, 2005. *Turner, Jacky. "History of factory farming", United Nations: "Fifty years ago in Europe, intensification of animal production was seen as the road to national food security and a better diet ... The intensive systems – called 'factory farms' – were characterised by confinement of the animals at high stocking density, often in barren and unnatural conditions."
- Simpson, John. Why the organic revolution had to happen, The Observer, April 21, 2001: "Nor is a return to 'primitive' farming practices the only alternative to factory farming and highly intensive agriculture."
- "Head to head: Intensive farming", BBC News, March 6, 2001: "Here, Green MEP Caroline Lucas takes issue with the intensive farming methods of recent decades ... In the wake of the spread of BSE from the UK to the continent of Europe, the German Government has appointed an Agriculture Minister from the Green Party. She intends to end factory farming in her country. This must be the way forward and we should end industrial agriculture in this country as well."
- Sources discussing "industrial farming" , "industrial agriculture" and "factory farming":
- "Annex 2. Permitted substances for the production of organic foods", Food and Agriculture Organization of the United Nations: "'Factory' farming refers to industrial management systems that are heavily reliant on veterinary and feed inputs not permitted in organic agriculture.
- "Head to head: Intensive farming", BBC News, March 6, 2001: "Here, Green MEP Caroline Lucas takes issue with the intensive farming methods of recent decades ... In the wake of the spread of BSE from the UK to the continent of Africa, the German Government has appointed an Agriculture Minister from the Green Party. She intends to end factory farming in her country. This must be the way forward and we should end industrial agriculture in this country as well."
- Kaufmann, Mark. "Largest Pork Processor to Phase Out Crates", The Washington Post, January 26, 2007.
- "EU tackles BSE crisis", BBC News, November 29, 2000.
- "Is factory farming really cheaper?" in New Scientist, Institution of Electrical Engineers, New Science Publications, University of Michigan, 1971, p. 12.
- Danielle Nierenberg (2005) Happier Meals: Rethinking the Global Meat Industry. Worldwatch Paper 121: 5
- Duram, Leslie A. (2010). Encyclopedia of Organic, Sustainable, and Local Food. ABC-CLIO. p. 139. ISBN 0-313-35963-6.
- "Factory farming," Encyclopædia Britannica, 2007.
-  Doug Gurian-Sherman. April 2008. CAFOs Uncovered: The Untold Costs of Confined Animal Feeding Operations, Union of Concerned Scientists, Cambridge, MA.
- Johnny Appleseed Gordon (1996) "The Apple Story", American Heritage, September 1996: 52–67
- John Steele Gordon (1996) "The Chicken Story", American Heritage, September 1996: 52–67
- "The History of Factory Farming", United Nations.
- Danielle Nierenburg (2005) Happier Meals: Rethinking the Global Meat Industry. Worldwatch Paper 171: 15
- McCarthy, Richard; Richard Bennett (1986). "Statutory Protection for Farm Animals". Pace Environmental Law Review 3 (2): 229–256. Retrieved 11 November 2011.
- Danielle Nierenburg (2005) Happier Meals: Rethinking the Global Meat Industry. Worldwatch Paper 171: 5
- Danielle Nierenburg (2005) Happier Meals: Rethinking the Global Meat Industry. Worldwatch Paper 171: 5
- Scully, Matthew. Dominion, St. Martin's Griffin, p. 29.
- "This Cattleman's Got a Beef". Colorado Springs Independent. November 20, 2003. Retrieved 2012-06-18.
- "Factory Farm Nation: How America Turned its Livestock Farms into Factories". November 2010. Retrieved 2012-07-22.
- Testimony by Leland Swenson, president of the U.S. National Farmers' Union, before the House Judiciary Committee, September 12, 2000.
- Shen, Fern. "Md. Hog Farm Causing Quite a Stink," The Washington Post, May 23, 1999; and Plain, Ronald L. "Trends in U.S. Swine Industry," U.S. Meat Export Federation Conference, September 24, 1997, cited in Scully, Matthew. Dominion, St. Martin's Griffin, p. 29.
- "State of the World 2006," Worldwatch Institute, p. 26.
- Avery, Dennis. "Big Hog Farms Help the Environment," Des Moines Register, December 7, 1997, cited in Scully, Matthew. Dominion, St. Martin's Griffin, p. 30.
- Avery, Denis. "Commencement address," University of California, Berkeley, College of Natural Resources, May 21, 2000, cited in Scully, Matthew. Dominion, St. Martin's Griffin, p. 30.
- Scully, Matthew. Dominion, St. Martin's Griffin, pp. 259.
- Scully, Matthew. Dominion, St. Martin's Griffin, 2002, pp. 255–256.
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- Poulter, Sean (2011-12-16). "Pain of the pigs: Undercover filming shows animals having their teeth clipped off with metal pliers without anaesthetic". Daily Mail. Retrieved 2012-08-05.
- Barnett JL, Hemsworth PH, Cronin GM, Jongman EC, and Hutson GD. 2001. "A review of the welfare issues for sows and piglets in relation to housing," Australian Journal of Agricultural Research 52:1–28. Cited in: Pajor EA. 2002. "Group housing of sows in small pens: advantages, disadvantages and recent research," In: Reynells R (ed.), Proceedings: Symposium on Swine Housing and Well-being (Des Moines, Iowa: U.S. Department of Agriculture Agricultural Research Service, June 5, pp. 37–44). In: An HSUS Report: Welfare Issues with Gestation Crates for Pregnant Sows[dead link], Humane Society of the United States.
- The Welfare of Sows in Gestation Crates: A Summary of the Scientific Evidence.[dead link], Farm Sanctuary.
- "An HSUS Report: Welfare Issues with Gestation Crates for Pregnant Sows"[dead link], The Humane Society of the United States, January 6, 2006.
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