A gestation crate, also known as a sow stall, is a metal enclosure used in intensive pig farming, in which a female breeding pig (sow) may be kept during pregnancy, and in effect for most of her adult life. The enclosures measure 6.6 ft x 2.0 ft (2 m x 60 cm) and house sows that weigh up to 600 lbs (270 kg).
The floors of the crates are made of concrete, and are slatted to allow waste to be collected below. As the sows outgrow the crates, they must sleep on their chests, unable to turn around. A few days before giving birth, they are moved to farrowing crates, where they are able to lie down to nurse while being held apart from their piglets.
Pork producers argue that they are needed because sows who are housed together will fight. Animal advocates regard their use as one of the most inhumane features of intensive animal agriculture. 
Between 60 and 70 percent of sows are kept in crates during pregnancy in the United States. Each pregnancy lasts for three months, three weeks, and three days. Sows will have an average of 2.5 litters every year for three or four years, most of which is spent in the crates. They give birth to between five and eight litters before being slaughtered. As they grow larger, they no longer fit in the crates, and have to sleep on their chests, unable to turn around to lie on their sides as pigs usually do. The crates are usually placed side by side in rows of 20 sows, 100 rows per shed. The floors are slatted to allow excrement and other waste to fall into a pit below.
A few days before giving birth, sows are moved to farrowing crates, which are slightly wider so they can lie down to nurse. Crates have 18-in. (46-cm.) "troughs" on each side where the piglets can safely lie without being in danger of sow overlay (when the sow lies down on top of a piglet).
One European analysis reports that there no difference between piglet mortality rates in Sweden, where farrowing crates are banned, and Denmark, where they are used. More recently, comparisons of piglet mortality in farrowing crates when compared with pens of 5 square metres or more, has shown that while mortality due to crushing was higher in pens, this was balanced by the higher rates of mortality in farrowing crates through piglets born dead or being savaged by the sow. Some farrowing pens in Switzerland allowed for the possibility of confinement in a crate, until crates were disallowed in 2007. A comparison between these pens and those that did not allow the possibility for confinement revealed no difference in piglet mortality from any causes.
Piglet survival also depends on selection pressure. Groups of piglets bred for higher survival showed no difference in mortality when weaned in farrowing crates and outdoor systems.
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In the European Union, the crates are being phased out after the fourth week of pregnancy by 2013. They are banned in Sweden and in the UK, and will be banned in Denmark in 2014. They will be phased out in New Zealand by 2015.
In the United States, they have been banned in Florida since 2002, Arizona since 2006, and California since late 2008. A Rhode Island law banning the crates, passed in June 2012, takes effect in June 2013. They are also being phased out in Maine and Oregon. Smithfield Foods, the largest pork producer in the United States, said in January 2007 that it will phase out gestation crates from its 187 piggeries over the next ten years, because of concerns from its customers. In 2009 the company stated it would no longer be able to phase them out in 10 years due to recent low sales, but reversed the decision in 2011 after intense pressure from the Humane Society of the United States.
In February 2012 McDonalds announced that it would begin working with suppliers to phase out the use of gestation crates, in response to pressure from the Humane Society of the United States and other animal advocates. McDonald's purchases around one percent of all pork in the United States.
Welfare issues 
Animal welfare advocates regard the use of gestation crates as one of the most inhumane features of intensive animal production. Temple Grandin of Colorado State University's Department of Animal Science said in 2007: "... basically you’re asking a sow to live in an airline seat."
Pork producers argue that gestation crates are needed because sows who are housed together in pens will fight, injuring or killing their fellow penmates. According to the U.S. National Pork Producers Council, the American Veterinary Medical Association "recognize[s] gestation stalls and group housing systems as appropriate for providing for the well-being of sows during pregnancy." While the practice of immobilizing the animals in crates helps limit fighting, it also increases the animals' stress levels, causing other health problems. The American Association of Swine Veterinarians adopted a position statement in 2002 specifying five standards of sow welfare and concluding, "Current scientific literature indicates that individual gestation stalls meet each of the aforementioned, provided the appropriate level of stockmanship is administered."
There are other ways of reducing, but not eliminating, aggression besides gestation crates. These include eliminating overcrowding, not mixing pigs from different litters, providing straw or other bedding material, and providing sufficient food that not only meets nutritional needs but satisfies the appetite.
Many studies have shown that sows in crates exhibit behavior such as bar-biting, head weaving, and tongue rolling. They also show behavior that indicates learned helplessness, according to Morris, such as remaining passive when poked or when a bucket of water is thrown over them. A review by the Scientific Veterinary Council of the European Commission states that repetitive "stereotypical" behavior has been found in "every detailed study" of pigs in gestation crates, but not in any other housing systems examined. A 2004 literature review by animal scientists determined that sows in stalls exhibited more "stereotypical" behavior than sows in group housing, but that animals housed in stalls had lower injury rates and higher farrowing rates.
Paul Sundberg, a veterinarian and vice president of the U.S. National Pork Producers Council, told The Washington Post: "Farmers treat their animals well because that's just good business. The key to sow welfare isn't whether they are kept in individual crates or group housing, but whether the system used is well managed." Sundberg said: "[S]cience tells us that she [a sow] doesn't even seem to know that she can't turn ... She wants to eat and feel safe, and she can do that very well in individual stalls."
The Washington Post reports that researchers have not found sows in gestation crates to have elevated levels of stress hormones. The paper notes that this suggests their overall health is not compromised. Other researchers say the pigs' behavior does indicate chronic frustration. Sows in crates bite the bars, chew even when they have no food, and press their water bottles obsessively, all reportedly signs of boredom. The Post(uncited reference) writes that a report by veterinarians for the European Union concluded that abnormal behavior in sows "develop[s] when the animal is severely or chronically frustrated. Hence their development indicates that the animal is having difficulty in coping and its welfare is poor."
- Rollin, Bernard E. Farm Animal Welfare: Social, Bioethical, and Research Issues. Iowa State University Press, 1995, p. 76.
- Reun, P.D.; Dial G.D.; Polson, D.D.; and Marsh W.E. "Breeding and gestation facilities for swine: matching biology to facility design", Veterinary Clinics of North America: Food Animal Practice 8(3):475–502, 1992.
- An HSUS Report: Welfare Issues with Gestation Crates for Pregnant Sows, Humane Society of the United States.
- Kaufmann, Marc. "In Pig Farming, Growing Concern, Raising Sows in Crates Is Questioned", The Washington Post, June 2001. (archived from the original on 2011-07-24)
- Kaufmann, Marc. "Largest Pork Processor to Phase Out Crates", The Washington Post, January 26, 2007.
- Webster J. 1994. Animal Welfare: A Cool Eye Towards Eden (Oxford, UK: Blackwell Science Ltd, cited in An HSUS Report: Welfare Issues with Gestation Crates for Pregnant Sows, Humane Society of the United States.
- "Obtaining optimal reproductive efficiency" (pdf), Swine News, North Carolina State Cooperative Extension Service, February 2006, Volume 29, Number 1
- Kaufmann, Marc. "In Pig Farming, Growing Concern, Raising Sows in Crates Is Questioned", The Washington Post, June 2001.
- SVC (Scientific Veterinary Committee) (1997). The welfare of intensively kept pigs. Commission of the European Communities, Directorate-General for Agriculture, Brussels..
- Weber R., Keil NM, Fehr M, Horat R. (2007) Piglet mortality on farms using farrowing systems with or without crates. Animal Welfare 16, 277–279
- Weber R., Keil NM, Fehr M, Horat R. (2009) Factors affecting piglet mortality in loose farrowing systems on commercial farms. Livestock Science 124, 216–222.
- Baxter EM, Edwards SA, Sherwood L, Farish M, Jarvis S (2007) Breeding for improved pre-weaning piglet survival in alternative farrowing systems. Proceedings of the 41st congress of the International Society for Applied Ethology (Galindo F and Alvarez L, eds.), Merida, Mexico.
- Carman, Tim. Pork industry gives sows room to move, The Washington Post, May 29, 2012.
- "Sow crates to be phased out by 2015 - National - NZ Herald News". The New Zealand Herald (NZPA). 1 December 2010. Retrieved 1 December 2010.
- Marcelo, Philip (21 June 2012). "New R.I. law bans cutting dairy-cow tails, raising pigs and calves in crates".
- Centner, TJ (2009) Limitations on the confinement of food animals in the United States. Journal of Agricultural and Environmental Ethics online first 
- Walzer, Philip (9 December 2012). "Smithfield to end use of gestation crates by 2017". Retrieved 31 July 2012.
- Strom, Stephanie (13 February 2012). "McDonald's Vows to Help End Use of Sow Crates". The New York Times.
- Shapiro, Paul. Pork industry should phase out gestation crates (Guest View), Globe Gazette, January 10, 2007.
- "AASV Position Statement: Pregnant Sow Housing." Accessed 31 July 2012.
- SA Weaver and MC Morris, "Science, pigs and politics: an New Zealand perspective on the phase-out of sow stalls," Journal of Agricultural and Environmental Ethics 17 (2003), 51–66.
- Morris, Michael C. "Sow stalls and farrowing crates – ethically, scientifically and economically indefensible", Organic New Zealand, 62, no. 1, Jan/Feb 2003, 38–39.
- McGlone, J.J. et al. "Compilation of the Scientific Literature Comparing Housing Systems for Gestating Sows and Gilts Using Measures of Physiology, Behavior, Performance, and Health," Professional Animal Scientist April 2004 vol. 20 no. 2 105-117.
Further reading 
- https://www.avma.org/KB/Resources/Reports/Documents/sow_housing_tfr.pdf A comprehensive review of housing for pregnant sows]. Journal of the American Veterinary Medical Association, Vol. 227, No. 10, Nov. 15, 2005. Accessed Aug. 1, 2012.
- Smith, Lewis W. "Forum—Observing Swine Behavior To Lower Piglet Mortality", Agriculture Research Service, United States Department of Agriculture.