Intensive animal farming

Intensive animal farming, industrial livestock production, and macro-farms, also known as factory farming, is a type of intensive agriculture used by the meat and dairy industry to maximize animal production while minimizing costs. To achieve this, agribusinesses keep livestock such as cattle, poultry, and fish at high stocking densities, at large scale, and using modern machinery, biotechnology, and pharmaceutics. The main products are meat, milk and eggs for human consumption.

While intensive animal farming can produce large amounts of animal products at a low cost with reduced human labor, it is controversial as it raises several ethical concerns, including animal welfare issues (confinement, mutilations, stress-induced aggression, breeding complications), harm to the environment and wildlife (greenhouse gases, deforestation, eutrophication), increased use of cropland to produce animal feed, public health risks (zoonotic diseases, pandemic risks, antibiotic resistance), and worker exploitation, particularly of undocumented workers. The animal agriculture industry has been accused of actively supporting disinformation campaigns and preventing policies to address climate change.

Industrial livestock production is important in most of the large meat-producing regions, such as Brazil, the United States, China, Argentina, Australia, New Zealand and the European Union, with expansion of megafarms or concentrated animal feeding operations.

Intensive animal farming is a relatively recent development in the history of agriculture, utilizing scientific discoveries and technological advances to enable changes in agricultural methods that increase production. Innovations from the late 19th century generally parallel developments in mass production in other industries in the latter part of the Industrial Revolution. 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.

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 era of 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 1966, the United States, United Kingdom and other industrialized nations, commenced factory farming of beef and dairy cattle and domestic pigs. As a result, farming became concentrated on fewer larger farms. For example, in 1967, there were one million pig farms in America; as of 2002, there were 114,000. In 1992, 28% of American pigs were raised on farms selling >5,000 pigs per year; as of 2022 this grew to 94.5%. From its American and West European heartland, intensive animal farming became globalized 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 intensive animal farming accounted for 30% of world meat production and by 2005, this had risen to 40%.

The aim is to produce large quantities of meat, eggs, or milk at the lowest possible cost. Food is supplied in place. Methods employed to maintain health and improve production may include the use of disinfectants, antimicrobial agents, anthelmintics, hormones and vaccines; protein, mineral and vitamin supplements; frequent health inspections; biosecurity; and climate-controlled facilities. Physical restraints, for example, fences or creeps, 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.

Industrial production was estimated to account for 39 percent of the sum of global production of these meats and 50 percent of total egg production. In the US, according to its National Pork Producers Council, 80 million of its 95 million pigs slaughtered each year are reared in industrial settings.