What Is Factory Farming?

Factory farming — or intensive animal farming — is the dominant method of food production globally. Understanding how it works is essential context for any discussion about food, ethics, or the environment.

What is factory farming?

Factory farming (officially called Concentrated Animal Feeding Operations, or CAFOs) refers to large-scale industrial facilities that raise animals at maximum density to minimise cost and maximise output. The system was developed in the post-World War II era, driven by the goal of making animal products cheap and abundant.

Chickens

Approximately 69 billion chickens are slaughtered globally each year. Broiler chickens (raised for meat) are bred for abnormally fast growth — reaching slaughter weight in 42 days, compared to 120 days for traditional breeds. Their bodies grow so rapidly that:

• Up to 30% develop chronic lameness
• Heart and lung problems are common due to disproportionate muscle growth
• They are densely packed — typical UK systems allow 33–38 kg/m² of space
• Lighting is manipulated to maximise feed conversion and growth

Pigs

Pigs are among the most intelligent animals on the planet — more cognitively complex than dogs. In factory farms:

• Breeding sows spend most of their lives in gestation crates — metal cages so small they cannot turn around. These are banned in the EU but still legal in most US states.
• Piglets have teeth clipped and tails docked — without anaesthetic — to prevent stress-induced aggression.
• Males are castrated (without anaesthetic in most countries) to prevent "boar taint."
• Pigs are slaughtered at 6 months, compared to a natural lifespan of 15+ years.

Cattle

Beef cattle spend part of their lives on pasture (where conditions are better) but are typically finished in feedlots — densely packed enclosures where they are fed grain to accelerate growth. Dairy cows are impregnated annually to maintain continuous milk production; calves are removed within hours of birth.

Dairy cows are kept pregnant for most of their short lives. They are slaughtered at 5–6 years old when yields decline. Their natural lifespan is 20 years.

Fish

Aquaculture now produces more fish than wild catch. Atlantic salmon farms, for example, keep fish at densities equivalent to a bathtub full of people — causing stress, disease, and high parasite (sea lice) loads. Mortality rates in salmon farms regularly exceed 20% annually.

The antibiotic crisis

Factory farming uses approximately 73% of the world's antibiotics— not primarily to treat disease, but as growth promoters and prophylactic measures to prevent the spread of disease in crowded conditions. This routine misuse is a leading driver of antibiotic-resistant bacteria (superbugs), which the WHO estimates could kill 10 million people per year by 2050.

Pandemics

The majority of new infectious diseases in humans are zoonotic — they originate in animals. Factory farms create ideal conditions for pathogen evolution: billions of genetically similar animals in close proximity, under immune stress. H5N1, H1N1, and many other influenza strains have emerged from factory farm conditions. Most epidemiologists consider another zoonotic pandemic originating in animal agriculture to be a matter of when, not if.

The legal framework

In most countries, animals used for food are explicitly excluded from the animal welfare laws that protect pets. "Standard agricultural practices" — including gestation crates, debeaking, and tail docking — are legal exemptions to anti-cruelty statutes. This creates a situation where the same actions that would be criminal if performed on a dog are entirely legal when performed on a pig or chicken.