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Slaughterhouses: What are they and how are animals killed in them?

Photo: Jo-Anne McArthur / We Animals Media

Every year billions of animals all over the world are transported to slaughterhouses, where the last hours of their lives are filled with suffering, surrounded by the fearful calls of hundreds of other animals facing the same fate. These facilities embody how our modern food systems prioritize speed and profit over the welfare of both animals and workers. The environment in slaughterhouses leads to cruelty against the animals, who face rampant abuse and mishandling as workers rush to keep up with the production line, risking injury to themselves in the process.

What is a slaughterhouse?

A slaughterhouse is where farmed animals go to be killed and have their bodies processed into food and other products. Every year billions of live animals enter slaughterhouses across the U.S. only to leave as cuts of meat or whole carcasses on refrigerator trucks, and as byproducts such as bones, blood, and inedible tissue that will end up as trash or be turned into glue or pet food.

Though a tiny minority of animals raised for their meat spend their lives prior to slaughter on farms that prioritize welfare considerations, and their lives may contain less suffering than the animals that live on factory farms, they end up going to the same slaughterhouses. This means that the ends of their lives are defined by the same immense suffering that characterizes the final moments of the animals who lived most of their lives on factory farms.

How does a slaughterhouse work?

The process that happens to an animal once they’ve reached the slaughterhouse varies based on the species of animal being slaughtered. However, the process will generally start with the animals arriving on trucks. Once they’ve arrived, they will be housed in holding pens, usually for no longer than a day. During this time they are usually offered water but no food, so that they have empty stomachs during processing. Slaughterhouses usually run 24 hours a day, meaning that while in the pens the animals are listening to those who arrived the day before being slaughtered.

Once they are driven out of their pens and into the slaughterhouse, the animals are stunned. However, one study that evaluated the efficacy of different stunning techniques in cattle and pigs found that none of the methods examined resulted in complete stunning 100 percent of the time. The captive bolt gun, which aims to stun using blunt force trauma, performed the worst and failed to adequately stun in 13.5 percent of cases.1

Once the animals have been stunned, they are typically hung by their legs to go through the actual slaughter process. This includes being drained of their blood, having their feathers, hair, or hide removed, decapitation, removing the organs, and cutting the carcass into pieces.

How are animals killed in a slaughterhouse?

Due to the frequent failure of pre-slaughter stunning to actually render animals unconscious, many of the animals are still conscious when they are dealt the killing blow, and remain conscious until they finally expire. The method most commonly used to kill animals at a slaughterhouse is to slit their throats. However, this process happens so quickly that mistakes are common, and animals often have not yet died when their bodies are plunged into a vat of boiling water to remove their hair or feathers.

Are slaughterhouses cruel?

Cruelty is inherent to slaughterhouses. One cannot kill other living beings on an industrial scale without cruelty. However, the animals are not the only victims of slaughterhouses; the workers also experience inhumane treatment.

Animal welfare

Forced fasting

Animals are frequently fasted immediately prior to slaughter so that when they are killed they do not have anything in their stomach or intestines, thus reducing the chance that the carcass of the animal will be contaminated during processing.

Inhumane transportation

Though there are very limited, inadequate, and underenforced legal protections for animals being transported to slaughter, animals are still often subject to hunger, thirst, fear, and stress on their way to the slaughterhouse. The conditions of transport often result in injuries such as bruising and broken bones and can even lead to death.

Animals are brutally abused inside slaughterhouses

There have been repeated reports of animal abuse within slaughterhouses. Cows that have fallen and can’t get back up again are dragged with chains and pushed across concrete floors with forklifts. These methods of compelling a cow to move are likely to result in severe and painful injuries, including torn skin, bruised muscle, and nerve damage.


Electrocution is used as a standard practice in slaughterhouses for killing a variety of animals including chickens and fish. In slaughterhouses handling fish, investigations have revealed that the fish are electrocuted to immobilize them and make handling and killing them easier, despite the fact that no evidence suggests that this prevents the fish from feeling any pain.

Cattle prods are used to make animals move

Cattle prods are electrified sticks often used to make cattle move in the desired direction. They can be used in ways classified as gentle, intense, or rough. When used roughly, they have the capability to damage a cow.2

Conditions in slaughterhouses are terrible

In slaughterhouses, workers are expected to slaughter and process animals with extremely fast line speeds. For some species, line speeds can exceed 1,000 animals slaughtered every hour, or more than 16 animals per minute. These line speeds put the animals at greater risk of not being stunned correctly and increase the likelihood that they will be handled roughly, while also increasing the chance of workers being hurt.

Worker exploitation

While working in slaughterhouses, laborers face extremely dangerous conditions. Due to the high turnover rate in slaughterhouse workforces, which can reach 100 percent annually, many employers seek out undocumented workers to replace the staff they lose. An estimated 38 percent of slaughterhouse and processing workers within the meat industry were born outside the United States.3

According to an account from a former slaughterhouse quality control manager, the dangers of working within the field are severe. Even if animals are stunned they can spasm and kick line staff. The workers herding the cattle into the slaughterhouse are also at risk of severe injury due to the sheer size of the cows being slaughtered and their fear. She also recounts the mental impact of working at a factory farm and the nightmares that plagued her sleep.

How many slaughterhouses are there in the world?

There are thousands of slaughterhouses processing farmed animals into meat and other products all over the world. In India alone there were an estimated 3600 slaughterhouses in 2017.

Due to the large variation in government regulation of slaughterhouses worldwide and the varying types, sizes, and record-keeping practices of slaughterhouses themselves, it is virtually impossible to ascertain exactly how many slaughterhouses there are on a global scale. Thanks to data from the Food and Agriculture Organization of the United Nations (FAO), we do know how many animals are slaughtered. In 2020, more than 73 billion (73,162,794,213) cows, chickens, pigs, and sheep were slaughtered around the world. When broken down by animal, China is responsible for the greatest number of cows, pigs, sheep, and fish slaughtered, and the United States is responsible for the greatest number of chickens killed for food.

How many slaughterhouses are there in the U.S. today?

At the beginning of 2022, 905 slaughterhouses processing red meat operated under federal inspection guidelines. This is an increase from 2021 when 858 slaughterhouses were operating at the beginning of the year. These numbers do not include facilities that killed only fish or birds such as chickens and turkeys.

In 2021, just 12 of the slaughterhouses that killed cattle were responsible for 50 percent of the total cattle killed. Of the plants slaughtering pigs, just the 14 largest slaughtered 58 percent of all pigs killed.

In 2018 there were 2,979 slaughter and processing facilities handling chickens, turkeys, and other birds. These facilities processed over 40 billion pounds of chicken meat.

Which state kills the most animals for meat?

In 2021, Nebraska was responsible for killing 7,093,400 animals for red meat—i.e., mammals that are killed for food. Though Nebraska was recorded as responsible for the greatest number of animals killed, Iowa slaughtered and processed the largest quantity of animals by weight, with a devastating 8.8 billion pounds of meat processed in 2021.


Billions of animals go through slaughterhouses every year. If they are lucky, they are successfully stunned before their bodies are deconstructed into the muscle and sinew that become our burgers and steak. Those that aren’t lucky endure suffering as they are hoisted up by their feet, their necks are cut, and the processing of their body begins. The worst part is that this suffering doesn’t have to happen. By choosing to eliminate meat from our plates we can take a stand against this kind of animal suffering. Farm Forward recommends eating conscientiously, as few animals as possible, ideally none.



M. von Wenzlawowicz, K. von Holleben, and E. Eser,  “Identifying Reasons for Stun Failures in Slaughterhouses for Cattle and Pigs: A Field Study,” Animal Welfare 21, Supplement 2 (June, 2012): 51–60,


Stella Maris Huertas, Rick E. A. M. Kempener, and Frank J. C. M. Van Eerdenberg, “Relationships Between Methods of Loading and Unloading, Carcass Bruising, and Animal Welfare in the Transportation of Extensively Reared Beef Cattle,” Animals 8, no. 7 (2018),


Angela Stuesse and Nathan T. Dollar, “Who are America’s meat and poultry workers?,” Economic Policy Institute, September 24, 2020,