Intensive animal farming, also called factory farming, is a method used by the meat and dairy industry to produce large amounts of animal products, such as meat, milk, and eggs, while keeping costs low. To do this, large farms raise animals like cows, chickens, and fish in very high numbers, using modern machines, technology, and medicines. These farms focus on efficiency and scale to meet the demand for food.
This type of farming can create large quantities of food at a low cost, but it is controversial. It raises concerns about how animals are treated, including keeping them in small spaces, performing painful procedures, and causing stress. It also harms the environment by increasing pollution, cutting down forests, and polluting water. Farming for animal products uses a lot of farmland to grow feed for animals. There are also risks to public health, such as diseases that spread from animals to people, the chance of major disease outbreaks, and germs that become resistant to medicines. Workers, especially those without legal documents, may also face unfair treatment. The animal agriculture industry has been criticized for spreading false information and blocking efforts to reduce climate change.
Industrial livestock farming is a major part of meat production in many large countries, including Brazil, the United States, China, Argentina, Australia, New Zealand, and the European Union. These areas are seeing growth in large farms or concentrated feeding operations.
History
Intensive animal farming is a new way of farming that started not long ago, using scientific discoveries and technology to change how food is produced. Innovations in the late 1800s were similar to changes in other industries during the Industrial Revolution. In the early 1900s, scientists learned about vitamins and how they help animals grow, which led to the use of vitamin supplements and allowed chickens to be raised indoors. The discovery of antibiotics and vaccines helped farmers raise more animals by reducing illness. Chemicals made during World War II were later used to create synthetic pesticides. Improvements in transportation and technology made it possible to move agricultural products long distances.
Between 1820 and 1975, global agricultural production increased four times to support a growing population, which rose from one billion people in 1800 to 6.5 billion in 2002. During this time, fewer people worked in farming because the process became more automated. In the 1930s, 24% of Americans worked in agriculture, but by 2002, only 1.5% did. In 1940, one farm worker fed 11 people, but by 2002, one worker fed 90 people.
In Britain, factory farming began in 1947 after a new law gave farmers money to use new technology and increase production, reducing the country’s need for imported meat. The United Nations stated that increasing animal farming helped provide more food for people. In 1966, the United States, United Kingdom, and other industrialized nations started factory farming for beef, dairy, and pigs. This led to fewer, larger farms. For example, in 1967, there were one million pig farms in America, but by 2002, there were 114,000. In 1992, 28% of American pigs were raised on farms that sold more than 5,000 pigs yearly, and by 2022, this increased to 94.5%. Starting in the 1990s, intensive animal farming spread worldwide, replacing traditional farming methods. In 1990, it produced 30% of the world’s meat, and by 2005, this rose to 40%.
Process
The goal is to create large amounts of meat, eggs, or milk at the lowest cost. Food is made and provided where it is needed. To keep animals healthy and improve production, methods such as cleaning with disinfectants, using medicines to fight germs, giving vaccines, adding nutrients like protein and vitamins, checking health often, keeping areas safe from germs, and using buildings with controlled temperature and air are used. Physical barriers, such as fences or enclosures, are used to stop animals from moving or acting in ways that are not wanted. Breeding programs are used to create animals that can survive well in confined spaces and produce food consistently.
Industrial farming is estimated to provide 39% of the total global production of these meats and 50% of all eggs produced. In the United States, 80 million out of 95 million pigs slaughtered each year are raised in industrial farms, according to the National Pork Producers Council.
Most of the industry’s focus happens during the slaughter and meat processing stages. Four major companies are responsible for processing 81% of cows, 73% of sheep, 57% of pigs, and 50% of chickens. This high concentration may be partly because rules make it hard for small slaughter plants to operate. Factory farming might not help small farmers more than traditional farming, as it may lead to too much production, which lowers prices. Meat companies often set prices for animals through agreements made before the animals are ready for sale. These practices can cause farmers to lose money, as half of all U.S. family farms did in 2007.
Many farmers want to sell animals directly to customers, but there are few USDA-inspected facilities where animals can be slaughtered and processed locally.
Small farmers are often part of factory farms, working as contract growers for large operations. In poultry farming, for example, farmers must pay for expensive buildings to house birds, buy feed and medicine, and often earn very little profit or even lose money.
In the United States, a major type of facility for raising large numbers of animals is the concentrated animal feeding operation (CAFO). Studies show that many workers in CAFOs receive little or no training about job dangers or safety. Workers who do not speak English well are less likely to get training, which is often only given in English. This leads some workers to not see their jobs as dangerous, causing them to not use protective equipment properly and increasing the risk of accidents. These workers are also less likely to report unsafe conditions or injuries.
Types
Intensive farms keep large numbers of animals, such as cows, pigs, turkeys, geese, and chickens, often indoors in high numbers. This type of farming is common in developed countries. In 2002–2003, the United Nations' Food and Agriculture Organization (FAO) estimated that 7% of global beef and veal, 0.8% of sheep and goat meat, 42% of pork, and 67% of poultry meat came from industrial production.
A major change in poultry farming during the 20th century was the discovery of vitamin D. This allowed chickens to be kept indoors all year round. Before this, chickens struggled during winter because they needed sunlight, which made egg production and meat production difficult outside of certain seasons. Year-round farming reduced costs, especially for broiler chickens.
Egg production also improved through scientific breeding. Early attempts, like those at the Maine Experiment Station, failed, but Professor Dryden at the Oregon Experiment Station later succeeded in increasing egg output.
As farming methods improved, fewer workers were needed. In the 1930s through the early 1950s, one American farm family could manage 1,500 hens. By the late 1950s, egg prices had dropped so much that farmers often kept three times as many hens, using cages designed for three birds instead of one or changing housing to hold more birds. Later, egg prices fell further, leading many farmers to leave the industry. This drop in prices made chicken and eggs more affordable, reducing their status as luxury foods.
Robert Plamondon noted that Rex Farms, the last family chicken farm in his area of Oregon, had 30,000 hens and operated into the 1990s. Today, modern egg farms typically house about 125,000 hens.
The egg and poultry industries became vertically integrated later, after major technological changes, such as modern broiler rearing techniques, the use of Cornish Cross broilers, and laying cages.
By the late 1950s, poultry farming had changed greatly. Large farms and packing plants could raise tens of thousands of birds. Chickens were sent to slaughterhouses, where they were processed into frozen or fresh products for sale. Today, meat-type chickens reach market weight in six to seven weeks, compared to three times as long fifty years ago. This is due to genetic improvements and better nutrition, not the use of growth hormones, which are banned in the U.S. and many other countries. Concerns about red meat’s cholesterol content in the 1980s and 1990s led to increased chicken consumption.
Today, eggs are produced on large farms with controlled environments. Chickens are exposed to artificial light to encourage year-round egg production. In the U.S., forced molting is common, where changes in light and food access cause hens to molt, increasing egg size and output. This practice is controversial and banned in the European Union.
On average, a chicken lays one egg per day, though this varies by breed and season. In 1900, the average was 83 eggs per hen per year. By 2000, this had risen to over 300. In the U.S., laying hens are typically slaughtered after their second egg-laying season. In Europe, they are usually slaughtered after one season. Hens begin laying eggs at about 18–20 weeks old. Male egg-type chickens have little value and are often killed shortly after hatching. Old hens also have little commercial value. As a result, traditional sources of poultry meat, such as spring chickens and stewing hens, have been replaced by meat-type broiler chickens.
Intensive piggeries, also called hog lots, are a type of concentrated animal feeding operation (CAFO) focused on raising pigs until they reach slaughter weight. Grower pigs are kept indoors in group housing or straw-lined sheds, while pregnant sows are confined in gestation crates and give birth in farrowing crates.
The use of gestation crates has lowered costs but raised animal welfare concerns. Countries like the U.S. and Canada widely use these crates, while the UK and some U.S. states, such as Florida and Arizona, have banned them.
Intensive piggeries are large, warehouse-like buildings. Indoor systems allow farmers to monitor pigs closely, reducing deaths and increasing productivity. Buildings are ventilated and temperature-controlled. Pigs lack sweat glands and cannot cool themselves, making them vulnerable to heat stress. Intensive systems prevent pigs from wallowing in mud, their natural cooling method, and instead use ventilation or drip water systems to control temperature.
Pigs are naturally omnivorous and are fed a mix of grains and protein sources, such as soybeans or meat and bone meal. Large farms may be near farmland where feed crops are grown, or they rely on the grains industry. Feed is either purchased pre-mixed or prepared on-site. In intensive systems, pigs are kept in individual stalls, allowing precise feed allocation and medication through feed. This helps manage disease spread, which is faster in close quarters. Preventive treatments, such as antibiotics, vitamins, and hormones, are often used to promote growth and health.
Indoor systems, especially stalls and pens, make waste collection easier. Manure is managed through lagoons or other waste systems, though odor remains a challenge.
Piglets often undergo procedures like castration, tail docking, teeth clipping, and ear notching to prevent injuries and aid identification. These are usually done without painkillers. Weak piglets may be killed shortly after birth.
Piglets are typically weaned from their mothers between two and five weeks old and moved to sheds. Grower pigs, which make up most of the herd, are housed in batch pens. During pregnancy, sows are often kept in stalls to control feeding and growth, and to prevent aggression like tail biting.
Regulation
In many areas, the way animals are raised in large numbers is controlled to protect the environment. In the United States, a type of large animal farming called a Concentrated Animal Feeding Operation (CAFO) must get a permit and follow a plan to manage waste, nutrients, and other materials. These rules are part of the federal Clean Water Act. Some information about how well these rules are followed is available. In 2000, the U.S. Environmental Protection Agency shared data about how 32 industries, including farming, performed environmentally over 5 years. This data mostly came from checking CAFOs. The checks and actions taken were mostly under the Clean Water Act, but also under the Clean Air Act and the Resource Conservation and Recovery Act. Among the 32 industries, farming was among the top seven for good environmental performance over 5 years and was one of the top two in the final year. Good performance means fewer problems found during checks. The ratios of problems found to total checks for farming were 0.05 over 5 years and 0.01 in the final year. In the final year, farming was also one of the top two industries with the fewest violations. In Canada, large-scale farming is regulated by provinces, and the names for these operations vary by province. Examples include Intensive Livestock Operations (Saskatchewan), Confined Feeding Operations (Alberta), Feedlots (British Columbia), High-density Permanent Outdoor Confinement Areas (Ontario), and Feedlots or Parcs d'Engraissement (Manitoba). Like other farming, large-scale animal farming in Canada must follow rules from both the federal government and provinces.
In the United States, half of all state animal cruelty laws do not cover farmed animals, including the federal Animal Welfare Act. A law from 1873, updated in 1994, requires that animals being transported for slaughter must be let out every 28 hours for food, water, and exercise. The U.S. Department of Agriculture says this rule does not apply to birds. A similar rule, the Humane Slaughter Act, passed in 1958, requires that animals be made unconscious before slaughter. This rule also excludes birds, rabbits, and fish, which make up most of the animals slaughtered for food. Each state has its own animal cruelty laws, but many also have "right-to-farm" laws that allow farming practices that might otherwise be considered cruel.
In the United States, efforts to regulate farms focus on large operations because they affect more animals and the environment. In New York State, many farms are not considered CAFOs because they have fewer than 300 cows. These farms are not regulated as strictly as CAFOs, which could lead to pollution and nutrient runoff. The EPA website shows that in New York's Bay watershed, there are 247 animal feeding operations, but only 68 have permits under the State Pollutant Discharge Elimination System (SPDES).
In Ohio, animal welfare groups reached an agreement with farming groups. In California, voters approved Proposition 2 in 2008, which sets rules for how farm animals can be kept. Other states have passed similar rules, and plans are being made in other states to create laws or ask voters to approve changes.
In 2009, the USDA proposed a plan called the Utilization of Manure and Other Agricultural and Industrial Byproducts. The goal is to protect the environment and health by using manure safely. This plan includes four steps:
– Improving how manure nutrients are used through better animal care and feeding.
– Making manure more useful by improving how it is collected, stored, and treated.
– Using manure in farming systems to help farms earn money and protect soil, water, and air.
– Using manure and other farming waste to create renewable energy.
In 2012, Australia's largest supermarket, Coles, said it would stop selling its own brand of pork and eggs from animals raised in factory farms starting in 2013. Another major supermarket, Woolworths, already began removing factory-farmed products. All of Woolworths' brand eggs are now cage-free, and by mid-2013, all its pork would come from farms that do not use stalls for animals.
In June 2021, the European Commission announced plans to ban cages for certain animals, including egg-laying hens, female breeding pigs, calves raised for veal, rabbits, ducks, and geese, by 2027.
Political influence and lobbying
In 2026, the UK government suggested changes to national planning rules to help build large farms that raise many animals. According to The Guardian, these changes were influenced by the British Poultry Council. Some groups said the changes might harm water quality, increase air pollution, and affect rural areas.
Animal welfare
In the United Kingdom, the Farm Animal Welfare Council was created by the government in 1979 to provide independent advice on animal welfare. It outlines five key principles for animal care: protection from hunger and thirst, discomfort, pain, injury, or disease; the ability to perform natural behaviors; and freedom from fear and distress.
Animal welfare standards vary globally, and rules continue to change as concerns about animal well-being grow. For example, the European Union is introducing new rules to limit how many meat chickens can be kept in a space, aiming to improve their living conditions. A UK minister stated, "The welfare of meat chickens is a major concern across the European Union. This agreement shows our commitment to animal welfare worldwide."
In Australia, factory farming methods are widely debated. Animals in these systems often live in small, crowded spaces, leading to stress and aggression. To reduce injuries, some animals have their beaks, tails, or teeth removed without pain relief. This can cause harm, with some piglets dying from shock after these procedures. Chickens in factory farms are sometimes kept in spaces smaller than an A4 sheet of paper.
Large-scale chicken production often uses fast, assembly-line processes. In the UK, removing chickens' beaks is not preferred but may be used to prevent serious fights and cannibalism among birds. In the United States, between 60% and 70% of six million breeding sows are kept in small gestation crates (2 by 7 feet) during pregnancy and most of their adult lives. Pork producers and veterinarians note that sows may fight if kept in larger pens. A major U.S. pork company announced in 2007 it would stop using gestation crates by 2017. The European Union banned gestation crates in 2013, effective after the fourth week of pregnancy.
As factory farming expands, more people are becoming aware of its issues, partly due to efforts by animal rights groups. Laws in the U.S., Europe, and other regions now aim to reduce the use of gestation crates and promote less confined farming practices.
In the United States, over 20 million chickens, 330,000 pigs, and 166,000 cattle die during transport to slaughterhouses each year. Some 800,000 pigs arrive unable to walk, often due to extreme temperatures or injuries.
Between 2011 and 2014, protests under the theme "We Are Fed Up!" in Berlin gathered 15,000 to 30,000 people annually to oppose industrial livestock farming. Global organizations have raised concerns about factory farming due to environmental, ethical, and health issues. These groups target farming practices, funding, and major meat producers. Key actions include "Animal Rights Day" in cities like Milan and Mexico City, the Global Day of Action to Stop World Bank Factory Farm Finance, and legal challenges against factory farms in the Global South.
Human health impact
According to the U.S. Centers for Disease Control and Prevention (CDC), farms where animals are kept in large numbers can cause health problems for workers. These workers may develop short-term or long-term lung diseases, injuries to muscles and bones, and infections that spread from animals to people, such as tuberculosis. People who live near these farms may also face risks, including breathing problems, a type of bacteria called MRSA, a disease called Q fever, and stress.
The CDC explains that harmful substances from animal waste, such as chemicals, bacteria, and viruses, can move through soil and water. People living near these farms often report issues like bad smells, insect problems, and health problems. The CDC has found that waste from animals can pollute rivers, lakes, and the air. Using antibiotics in animals may create germs that are hard to treat with medicines. Also, waste from animals can release harmful chemicals that lower oxygen in water, pollute drinking water, and affect fish and plants. Pesticides and hormones used on farms may change fish behavior, and materials like animal feed can harm plants and help disease-causing germs grow. Harmful substances like arsenic and copper from animal waste can also pollute water.
Pesticides are used to kill harmful insects and protect crops from damage. In the United States, about 25% of pesticides are used in homes, parks, and other non-farm areas, while 70% are used in farming. However, pesticides can enter people’s bodies and cause health issues. One way this happens is through the build-up of pesticides in animals raised on large farms.
In the European Union, growth hormones are not allowed because it is hard to determine safe levels. The United Kingdom says it would only consider using specific hormones if proven safe in the future. In 1998, the EU banned giving animals antibiotics that are important for human health. In 2006, the EU also banned using drugs in animals for growth purposes. These actions helped reduce the spread of germs that are hard to treat with medicines.
In the United States, antibiotics are still widely used in animals. The FDA reports that 80% of all antibiotics sold in 2009 were given to livestock. Many of these antibiotics are similar to those used to treat people. This use has made some medicines less effective for humans, and the cost of treating drug-resistant infections in the U.S. is between $16.6 billion and $26 billion each year.
Diseases that spread from animals to humans, such as the coronavirus that caused the COVID-19 pandemic, are becoming more common because of changes in the environment caused by large-scale farming. Activities like cutting down forests, building roads, and growing cities bring people closer to animals they rarely meet. This increases the chance of diseases spreading from animals to humans. The international trade of animal products also raises the risk of diseases like swine fever, BSE, foot-and-mouth disease, and bird flu spreading worldwide.
Large-scale farming can make it easier for harmful diseases to develop and spread. Many diseases spread quickly among animals that are kept close together, and crowding increases the chance of genetic changes in germs. However, small family farms may be more likely to introduce bird diseases into human populations, as seen during the 2009 flu outbreak.
MRSA, a type of bacteria that is hard to treat, has been found in pigs and humans, raising concerns about pigs spreading this infection. A study found that 20% of pig farmers in the U.S. and Canada had MRSA in 2007. Another study showed that 81% of pig farms in the Netherlands had MRSA in pigs, and 39% of pigs at slaughter had the bacteria. These germs were often resistant to certain medicines. A recent study found that a specific type of MRSA, called CC398, is less affected by a medicine used in farming. This type of MRSA has spread to animals raised in large numbers, such as pigs, cows, and chickens, and can infect humans. Although dangerous, CC398 often does not cause symptoms in animals used for food.
A 2011 study found that nearly half of meat and poultry sold in U.S. grocery stores had a type of bacteria called S. aureus, and more than half of these bacteria were resistant to at least three types of antibiotics. Even though cooking can kill this bacteria, improper food handling and kitchen practices may still put people at risk. The lead researcher of the study said the high levels of drug-resistant S. aureus in food animals are concerning and highlight the need to carefully manage antibiotic use in farming.
In April 2009, lawmakers in the Mexican state of Veracruz claimed that large pig and chicken farms were linked to a swine flu outbreak that killed more than 100 people. They did not provide scientific proof for this claim. The flu outbreak appeared to start near a pig farm owned by a company called Smithfield.
Environmental impact
Making meat and other animal products causes a lot of harm to the environment, increases global warming, and reduces the variety of plants and animals compared to making food from plants. However, compared to farming animals on large areas of land, factory farming uses less land and produces fewer greenhouse gases for the same amount of food.
The environmental impacts of factory farming include:
– Cutting down forests to grow food for animals.
– Using too much land to grow high-protein and high-energy food for animals.
– Making and using chemicals like pesticides and fertilizers to grow animal feed.
– Using too much water to grow crops that feed animals, including taking water from underground.
– Polluting soil, water, and air with nitrogen and phosphorus from fertilizers and animal waste.
– Losing different types of plants and animals because of too much nitrogen, acid, pesticides, and herbicides.
– Fewer different types of farm animals and losing traditional breeds around the world.
– Animals going extinct because farming takes over their homes, especially when growing crops to feed animals.
Studies show that chicken raised in intensive farms has the least environmental harm, while beef from grass-fed cows has the most. People who care about animals say that factory farming is more efficient, making meat cheaper and leading to more people wanting to buy it.
Intensive farming creates a lot of waste that pollutes the air, soil, and water. On pig farms with many animals, they are usually kept on concrete floors with slats so waste can drain away. The waste is stored as slurry, which is a mix of urine and feces in liquid form. When stored, slurry releases methane gas, and when spread on fields, it releases nitrous oxide and pollutes land and water with nitrogen. A lot of waste is created. Air and groundwater can be harmed if animal waste is not handled properly.