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 × 2.0 ft (2 m × 60 cm) and house sows that weigh up to 900 lbs (408 kg).
The floors of the crates are made of concrete, and are slatted to allow waste to be collected below. A few days before giving birth, they are moved to farrowing crates, where they are able to lie down to nurse and the piglets have room on the sides to get away from the sow to sleep and play.
Opponents of gestation crates believe that they are unhealthy and constitute animal abuse, while proponents argue they are needed because sows, like most animals that live in groups, would develop a social hierarchy and fight between themselves.
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 is 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 and in Australia by 2017.
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 Colorado, Maine, Michigan, Ohio 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 ten 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.
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 limits fighting, it subsequently 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. Some studies have show that "sow behavior has been shown to differ among housing systems; often it seems to be the non-housing component (i.e., direction of bar, other substances present) of the system that is responsible for the behavior displayed by the sow."
Paul Sundberg, a veterinarian and vice president of the U.S. National Pork Board, 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. Some producers in Europe use a “free access” maternity pen configuration in which sows are in individual pens for the first four weeks of pregnancy but can “unlock” the stall by backing out and entering a common area. The producers observed that pregnant pigs will stay in the individual pens more than 90 percent of the time, and return to the same stall more than 90 percent of the time. 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."
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