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Workers and cattle in a slaughterhouse

A slaughterhouse or abattoir Listeni/ˈæbətwɑr/ or meatworks is a facility where animals are killed for consumption as food products. Slaughterhouses which process meat not intended for human consumption are sometimes referred to as Knacker's yards or Knackeries.

In the United States, around nine billion animals are slaughtered every year.[citation needed] (this includes about 150.4 million cattle, bison, sheep, hogs, and goats and 8.9 billion chickens, turkeys, ducks, etc.;[citation needed] in 2009, 13,450,000 long tons (13,670,000 t) of beef were consumed in the U.S. alone.[1] In Canada, 650 million animals are killed annually.[2] In the European Union, the annual figure is 300 million cattle, sheep, and pigs, and four billion (an unverified number) chickens.[citation needed]

Slaughtering animals on a large scale poses significant logistical problems and public health requirements.[citation needed] Public aversion to meat packing in many cultures influences the location of slaughterhouses. In addition, some religions stipulate certain conditions for the slaughter of animals.

There has been criticism of the methods of transport, preparation, herding, and killing within some slaughterhouses, and in particular of the speed with which the slaughter is sometimes conducted. Investigations by animal welfare and animal rights groups have indicated that in some cases animals are skinned or gutted while alive and conscious. In some cases animals are driven for hundreds of miles to slaughterhouses in conditions that often result in injuries and death en route.[3] Slaughtering animals is opposed by animal rights groups on ethical grounds.[4]


Typically 45–50% of the animal can be turned into edible products (meat). About 5-15% is waste, and the remaining 40–45% of the animal is turned into byproducts such as leather, soaps, candles (tallow), and adhesives.[citation needed]


In the slaughterhouse, Lovis Corinth, 1893.

Early maps of London show numerous stockyards in the periphery of the city, where slaughter occurred in the open air. A term for such open-air slaughterhouse is a shambles. There are streets named "The Shambles" in some English towns (e.g. Worcester, York) which got their name from having been the site on which butchers killed and prepared animals for consumption .[citation needed]

In her article "A Social History of the Slaughterhouse,"[5] Amy Fitzgerald argues that the slaughterhouse as a "unique institution" emerged in the eighteenth century. Prior to this, animals were “slaughtered for consumption in diverse places” (59). In the eighteenth and nineteenth centuries, a combination of health and social concerns led “reformers” to call for the isolation and sequester of animal slaughter. These reformers were concerned with the hygene and disease as well as the effect the killing would have both on the butchers and the observers, which one critic of the time claimed “educate[d] the men in the practice of violence and cruelty, so that they seem to have no restraint on the use of it.” As a result of this tension, meat markets within the city were closed and abattoirs built outside city limits. In 1747, an ordinance in the United States “forbade people from slaughtering cattle at their home." An additional motivation for eliminating private slaughter was to allow for the careful regulation of the “morally dangerous” task of putting animals to death (60)

This new demand for concealment and regulation, combined with a continued demand for meat led to the primacy of the “slaughterhouse” as a unique site for the killing of animals for meat(59). Technical innovations catapulted the growth of the meat industry. The invention of the refrigerator car as well as expansion of the railroad allowed for feasible, safe transportation of meat (and later enabling the isolation of slaughterhouses outside of population centers). Additionally, Meat-packing millionaire [Philip Armour]’s invention of the “disassembly line” greatly increased the productivity and profit margin of industrial meatpacking businesses: “according to some, animal slaughtering became the first mass-production industry in the United States, from which Henry Ford partially adapted his conception of assembly-line production. The industry continued to expand during this period as a result of increasing demand and increased distribution possibilities” (61). This expansion has been accompanied by increased concern about the physical and mental conditions of the workers along with contreversy over the ethical and environmental implications of slaughtering animals for meat. [5]


In the latter part of the 20th century, the layout and design of most U.S. slaughterhouses was influenced by the work of Dr. Temple Grandin.[6] She suggested that reducing the stress of animals being led to slaughter may help slaughterhouse operators improve efficiency and profit.[7] In particular she applied an understanding of animal psychology to design pens and corrals which funnel a herd of animals arriving at a slaughterhouse into a single file ready for slaughter. Her corrals employ long sweeping curves[8][9][10] so that each animal is prevented from seeing what lies ahead and just concentrates on the hind quarters of the animal in front of it. This design – along with the design elements of solid sides, solid crowd gate, and reduced noise at the end point – work together to encourage animals forward in the chute and to not reverse direction.[11]

As of 2011 Grandin claimed to have designed over 54% of the slaughterhouses in the United States as well as many others around the world.[citation needed]

Mobile design[edit]

By 2010 a mobile facility the Modular Harvest System had received USDA approval. It can be moved from ranch to ranch. It consists of three trailers, one for slaughtering, one for consumable body parts and one for other body parts. Preparation of individual cuts is done at a butchery or other meat preparation facility.[12]


A row of hanging carcases.

The slaughterhouse process differs by species and region and may be controlled by civil law as well as religious laws such as Kosher and Halal laws. A typical U.S. procedure follows:

  1. Cattle (mostly steers and heifers, some cows, and even fewer bulls) arrive via truck or rail from a ranch, farm, or feedlot.
  2. Place animals in holding pens.
  3. Incapacitate them by applying an electric shock of 300 volts and 2 amps to the back of the head, effectively stunning them,[13] or by use of a captive bolt pistol to the front of the cow's head (a pneumatic or cartridge-fired captive bolt). Swine can be rendered unconscious by CO2/inert gas stunning. (This step is prohibited under strict application of Halal and Kashrut codes.)
  4. Hang them upside down by both of their hind legs and place them on the processing line.
  5. Sever the carotid artery and jugular vein with a knife. The blood drains from the body, causing death through exsanguination.
  6. Remove the head and feet.
  7. Cut around the digestive tract to prevent fecal contamination later in the process.
  8. Remove the hide/skin by "down pullers", "side pullers" and "fisting" off the pelt (sheep and goats). Hides can also be removed by laying the carcase on a cradle and skinning with a knife.
  9. Remove internal organs and inspect them for parasites and signs of disease. Separate the viscera from the heart and lungs, referred to as the "pluck" for inspection. Also separate livers for inspection. Drop or remove tongues from the head, and send the head down the line on head hooks or head racks for inspection of the lymph nodes for signs of systemic disease.
  10. A government inspector inspects the carcass for safety. (This inspection is performed by the Food Safety Inspection Service in the U.S., and Canadian Food Inspection Agency in Canada.)
  11. Reduce levels of bacteria using interventions such as steam, hot water, and organic acids.
  12. Optionally electrically stimulate cattle and sheep (only) to improve meat tenderness.
  13. Chill carcases to prevent the growth of microorganisms and to reduce meat deterioration while the meat awaits distribution.
  14. Cut the chilled carcase into primal cuts, subprimals and/or leave intact as a "side" of meat. Beef and horse carcases are always split in half and then quartered, pork is split into sides only and goat/veal/mutton and lamb is left whole.
  15. The remaining carcase may be further processed to extract any residual traces of meat, usually termed advanced meat recovery or mechanically separated meat, for human or animal consumption.
  16. Materials such as bone, lard or tallow, are sent to a rendering plant. Also, lard and tallow can be used for the production of biodiesel or heating oil.
  17. The wastewater, consisting of blood and fecal matter, generated by the slaughtering process is sent to a waste water treatment plant.
  18. The meat is transported to distribution centers that then distribute to retail markets.

International variations[edit]

The standards and regulations governing slaughterhouses vary considerably around the world. In many countries the slaughter of animals is regulated by custom and tradition rather than by law. In the non-Western world, including the Arab world, the Indian sub-continent, etc., both forms of meat are available: one which is produced in modern mechanized slaughterhouses, and the other from local butcher shops.

In some communities[which?] animal slaughter may be controlled by religious laws, most notably halal for Muslims and kashrut for Jewish communities. These both require that the animals being slaughtered should be conscious at the point of death,[citation needed] and as such animals cannot be stunned prior to killing. This can cause conflicts with national regulations when a slaughterhouse adhering to the rules of religious preparation is located in some Western countries. In Islamic and Jewish law, captive bolts and other methods of pre-slaughter paralysis are generally not permissible, due to it being forbidden for an animal to be killed prior to slaughter. Various halal food authorities have more recently permitted the use of a recently developed fail-safe system of head-only stunning where the shock is less painful and non-fatal, and where it is possible to reverse the procedure and revive the animal after the shock.

In many societies,[which?] traditional cultural and religious aversion to slaughter led to prejudice against the people involved. In Japan, where the ban on slaughter of livestock for food[specify] was lifted only in the late 19th century, the newly found slaughter industry drew workers primarily from villages of burakumin, who traditionally worked in occupations relating to death (such as executioners and undertakers). In some parts of western Japan, prejudice faced by current and former residents of such areas (burakumin "hamlet people") is still a sensitive issue. Because of this, even the Japanese word for "slaughter" (屠殺 tosatsu) is deemed politically incorrect by some pressure groups as its inclusion of the kanji for "kill" (殺) supposedly portrays those who practice it in a negative manner.

Some countries[which?] have laws that exclude specific animal species or grades of animal from being slaughtered for human consumption, especially those that are taboo food. The former Indian Prime Minister Atal Bihari Vajpayee suggested in 2004 introducing legislation banning the slaughter of cows throughout India, as Hinduism holds cows as sacred and considers their slaughter unthinkable and offensive. This was often opposed on grounds of religious freedom. The slaughter of cows and the importation of beef into the nation of Nepal are strictly forbidden.


USDA inspection of pig.

Most countries have laws in regard to the treatment of animals at slaughterhouses. In the United States, there is the Humane Slaughter Act of 1958, a law requiring that all swine, sheep, cattle, and horses be stunned unconscious with application of a stunning device by a trained person before being hoisted up on the line. There is some debate over the enforcement of this act. This act, like those in many countries, exempts slaughter in accordance to religious law, such as kosher shechita and dhabiha halal. Most strict interpretations of kashrut require that the animal be fully sensible when its carotid artery is cut.[citation needed]

The novel The Jungle detailed unsanitary conditions in slaughterhouses and the meatpacking industry during the 1800s. This led directly to an investigation commissioned directly by President Theodore Roosevelt, and to the passage of the Meat Inspection Act and the Pure Food and Drug Act of 1906, which established the Food and Drug Administration. A much larger body of regulation deals with the public health and worker safety regulation and inspection.

Animal welfare concerns[edit]

For her book Slaughterhouse, Gail Eisnitz, chief investigator for the Humane Farming Association (HFA),[14] interviewed slaughterhouse workers in the U.S. who say that, because of the speed with which they are required to work, animals are routinely skinned while apparently alive, and still blinking, kicking, and shrieking. Eisnitz argues that this is not only cruel to the animals, but also dangerous for the human workers, as cows weighing several thousands of pounds thrashing around in pain are likely to kick out and debilitate anyone working near them.[15]

According to the HFA, Eiznitz interviewed slaughterhouse workers representing over two million hours of experience, who, without exception, told her that they have beaten, strangled, boiled, and dismembered animals alive, or have failed to report those who do. The workers described the effects the violence has had on their personal lives, with several admitting to being physically abusive or taking to alcohol and other drugs.[16]

The HFA alleges that workers are required to kill up to 1,100 hogs an hour, and end up taking their frustration out on the animals.[16] Eisnitz interviewed one worker, who had worked in ten slaughterhouses, about pig production. He told her:

Hogs get stressed out pretty easy. If you prod them too much, they have heart attacks. If you get a hog in the chute that's had the shit prodded out of him and has a heart attack or refuses to move, you take a meat hook and hook it into his bunghole. You try to do this by clipping the hipbone. Then you drag him backwards. You're dragging these hogs alive, and a lot of times the meat hook rips out of the bunghole. I've seen hamsthighs — completely ripped open. I've also seen intestines come out. If the hog collapses near the front of the chute, you shove the meat hook into his cheek and drag him forward.[17]

Over the last few decades, some research has been done toward making slaughterhouses more humane; one well-known scientist in this field is Temple Grandin.


Historically, some doubted that fish could experience pain. However, laboratory experiments have shown that fish do react to painful stimuli (e.g. injections of bee venom) in a similar way to mammals.[18][19] The expansion of fish farming as well as animal welfare concerns in society has led to research into more humane and faster ways of killing fish.[20] In large-scale operations like fish farms, stunning fish with electricity or putting them into water saturated with nitrogen so that they cannot breathe, results in death more rapidly than just taking them out of the water. For sport fishing, it is recommended that fish be killed soon after catching them by hitting them on the head followed by bleeding out, or by stabbing the brain with a sharp object[21] (called pithing or ike jime in Japanese).

Major slaughterhouses[edit]

The largest slaughterhouse in the world is operated by the Smithfield Packing Company in Tar Heel, North Carolina. It is capable of butchering over 32,000 pigs a day. In the US, the majority of major meat packing plants are located in the Midwestern and High Plains regions.[citation needed] The Mina Slaughterhouse in the Kingdom of Saudi Arabia, operated by the Ministry of Public Works and Housing, has a capacity of 22,000 head of sheep per hour, equivalent to 300,000 head per day. During the Islamic Hajj religious festival period, it is the largest meat processing plant in the world employing 24,000 workers.

See also[edit]


  1. ^ "U.S. Beef and Cattle Industry", United States Department of Agriculture, cited in Torres, Bob. Making a Killing. AK Press, 2007, p. 45.
  2. ^ "Slaughterhouses", Global Action Network. Retrieved March 18, 2008.
  3. ^ See, for example, Vansickle, J. "Quality Assurance Program Launched," National Hog Farmer, February 15, 2002, which reports that each year 420,000 pigs are crippled and 170,000 killed during transport to slaughterhouses, cited in Williams, Erin E. and DeMello, Margo. Why Animals Matter. Prometheus Books, 2007, p. 49.
  4. ^ Hansen, Marci, "Animal Rights" in Sherrod, Lonnie R. (ed.), Youth Activism: An International Encyclopedia, Volume 1 (Greenwood Publishing, 2006), pp. 70–1.
  5. ^ a b
  6. ^ Grandin, T. "Best Practices for Animal Handling and Stunning"", Meat & Poultry, April 2000, p.76.
  7. ^ Grandin, T. and Deesing, M. "Humane Livestock Handling" 2008. Storey Publishing, North Adams, MA, USA.
  8. ^ [Temple] (September 2011). "Directions for laying out curved cattle handling facilities for ranches, feedlots, and properties". Dr. Temple Grandin's Web Page. Dr. Temple Grandin. Retrieved 2012-12-10.  "Round crowd pens and curved single file chutes work better than straight ones, but they must be laid out correctly. A curved chute works more efficiently than a straight one because it prevents cattle from seeing people and other activities at the end of the chute." "A round crowd pen will work better than a straight crowd pen because, as cattle go around a 180° turn, they think they are going back to where they came from "
  9. ^ [Temple] (July 2011). "Sample Designs of Cattle Races and Corrals". Dr. Temple Grandin's Web Page. Dr. Temple Grandin. Retrieved 2012-12-10.  Why does a curved chute and round crowd pen work better than a straight one? As the animals go around the curve, they think they are going back to where they came from. The animals can not see people and other moving objects at the end of the chute. It takes advantage of the natural circling behaviour of cattle and sheep.
  10. ^ [Temple] (1993). "Teaching Principles of Behavior and Equipment Design for Handling Livestock". J. Anim. Sci. J. Anim. Sci. Retrieved 2012-12-10.  Some of the design principles that are taught are the use of solid sides on chutes and crowd pens to prevent animals from seeing out with their wide-angle vision and layout of curved chutes and round crowd pens. A circular crowd pen and a curved chute reduced the time spent moving cattle by up to 50% (Vowles and Hollier, 1982 [Vowles, W. J., and T. J. Hollier. 1982. The influence of yard design on the movement of animals. Proc. Aust. Soc. Anim. Prod. 14:597]).
  11. ^ [Temple] (July 2010). "Improving the Movement of Cattle, Pigs, and Sheep during handling on farms, ranches, and slaughter plants". Dr Temple Grandin. Retrieved 2012-12-10.  Cattle will move more easily through a curved race. Solid sides which prevent the cattle from seeing people and other distractions outside the fence should be installed on the chutes (races) and the crowd pen which leads up to the single file chute. The use of solid sides is especially important in slaughter plants, truck loading ramps, and other places where there is lots of activity outside the fence. Solid sides are essential in slaughter plants to block the animal's view of people and equipment. A curved chute (race) with solid sides at a ranch facility. It works better than a straight chute because cattle think they are going back to where they came from. The outer fence is solid to prevent the cattle from seeing distractions outside the fence... The facility must be located in a pasture that has no nearby equipment, moving vehicles or extra people, or put inside a building that has solid side walls. In many facilities, adding solid fences will improve animal movement... Solid sides in these areas help prevent cattle from becoming agitated when they see activity outside the fence -- such as people. Cattle tend to be calmer in a chute with solid sides. Cattle move more easily through the curved race system because they can not see people and other distractions ahead.
  12. ^ Muhlke, Christine (23 May 2010). "FIELD REPORT; A Movable Beast". The New York Times. p. 22. 
  13. ^ "Guidelines for the Slaughter of Animals".  USDA
  14. ^ Humane Farming Association Website
  15. ^ Eisnitz, Gail A. Slaughterhouse. Prometheus Books, 1997, cited in Torres, Bob. Making a Killing. AK Press, 2007, p. 46.
  16. ^ a b "HFA Exposé Uncovers Federal Crimes", Humane Farming Association. Retrieved March 8, 2008.
  17. ^ Eisnitz, p. 82, cites in Torres, Bob. Making a Killing. AK Press, 2007, p. 47.
  18. ^ Sneddon, LU (2009). "Pain perception in fish: indicators and endpoints.". ILAR Journal 50 (4): 38–42. PMID 19949250. 
  19. ^ Oidtmann, B; Hoffman RW (Jul–Aug 2001). "Pain and suffering in fish". Berliner und Münchener tierärztliche Wochenschrift 114 (7-8): 277–82. PMID 11505801. 
  20. ^ Lund, V; Mejdell CM, Röcklinsberg H, Anthony R, Håstein T (2007-05-04). "Expanding the moral circle: farmed fish as objects of moral concern.". Diseases of aquatic organisms 72 (2): 109–118. doi:10.3354/dao075109. PMID 17578250. 
  21. ^ Davie, PS; Kopf RK (August 2006). "Physiology, behaviour and welfare of fish during recreational fishing and after release.". New Zealand veterinary journal 54 (4): 161–172. doi:10.1080/00480169.2006.36690. PMID 16915337. 

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