As part of its ongoing campaign to help end the use of commercial gestation crates -- a much maligned practice that involves the confinement of pregnant pigs for much of their life -- the Humane Society of the United States (HSUS) has announced plans to sue 51 such industrial-style operations for unreported releases of ammonia.

Ammonia is a potentially-dangerous pollutant and the EPA requires facilities to report releases of it amounting to more than 100 pounds within a 24-hour period. HSUS says the 51 facilities, located in top pork-producing states Iowa, North Carolina and Oklahoma, all release amounts that exceed this requirement.

The organization explains more in a release:

It was no surprise to find that many of those receiving notice are affiliated with the leaders and spokespersons of the National Pork Producers Council, a trade group that defends confining pigs in cramped gestation crates. The crates are so restrictive that the animals cannot even turn around in them. Each of these operations confines thousands, if not tens of thousands, of pigs—with the females typically in gestation crates— and emits hundreds of pounds of airborne ammonia per day. As a result, they regularly endanger communities, farm animals, wildlife and the environment.

HSUS told Pork Network that it determined which production sites to sue after "months of research" using "a simple and readily available mathematical equation to estimate the amount of ammonia being released from each of the facilities.” The equation can be found on the EPA and National Pork Producers Council websites, and figures in the number and types of animals at a facility and the waste-management methods employed.

However, director of environmental programs for the National Pork Board Allan Stokes countered to the publication that the equation is meant only as an aid for livestock producers, "not as a regulatory tool or an absolute determinant of whether a livestock operation in fact exceeded any regulatory reporting thresholds."

Stokes also said the equation doesn't account for any ammonia mitigation techniques that might be in place, and Pork Network notes that an HSUS representative admitted that no on-farm emissions tests have yet been conducted.

The Humane Society has been vocal in its mission to discourage organizations from getting pork from companies that use gestation crates. Many major food companies in recent months have pledged to take steps to eliminate them, including McDonald's, Kraft Foods and others.

Here are other major food companies that have pledged to ban the practice:

Photo by Flickr user S H Photos.

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  • McDonald's

    At the end of May, the country's leading hamburger chain by sales announced a plan to eliminate its suppliers' use of gestation crates by 2022.

  • Denny's

    On May 15, Denny's announced it would work with its suppliers to end the use of gestation crates for its pork products.

  • Safeway

    In May, Safeway -- the country's second-largest grocery chain -- said it plans to <a href="http://www.huffingtonpost.com/huff-wires/20120507/us-safeway-humane-pork/" target="_hplink">stop buying meat</a> from suppliers that use gestation crates.

  • Burger King

    On April 23, Burger King pledged to <a href="http://www.huffingtonpost.com/2012/04/25/burger-king-gestation-crates_n_1451703.html" target="_hplink">eliminate the use of pork from pigs raised in crates by 2017</a>. The company also pledged to offer entirely cage-free eggs by 2017.

  • Wendy's

    In March, Wendy's announced it would work with its U.S. and Canadian pork suppliers to <a href="http://www.huffingtonpost.com/2012/03/23/wendys-animal-treatment_n_1375724.html" target="_hplink">phase out the use of gestation crates</a>.

  • Compass Group

    Also in March, Compass Group announced it would <a href="http://www.bizjournals.com/charlotte/blog/going_green/2012/03/compass-group-will-end-contracts-with.html" target="_hplink">phase out the use of meat from pigs raised in gestation crates</a> by 2017. Compass Group runs dining operations at about 10,000 companies, hospitals, senior living centers, schools, colleges and universities, making it the largest food service company in the world.

  • McDonald's

    McDonald's also announced in February its <a href="http://www.huffingtonpost.com/2012/02/14/mcdonalds-gestation-crates_n_1275942.html" target="_hplink">plan to stop using meat from pig raised in the crates</a> by 2017.

  • Hormel, the maker of products like Spam, announced in February it <a href="http://www.huffingtonpost.com/2012/02/02/hormel-gestation-crates_n_1249707.html" target="_hplink">pledges to eliminate most gestation crates by 2017</a>.

  • Bon Appétit Management Company

    Also in February, Bon Appetit announced it would <a href="http://www.latimes.com/business/money/la-fi-mo-bon-appetit-gestation-crates-20120220,0,7675759.story" target="_hplink">stop buying pork from providers who use gestation cates</a>. Bon Appetit runs more than 400 cafes across 31 states.

  • Smithfield Foods

    Smithfield Foods, the world's largest pork producer, announced late last year it would <a href="http://www.huffingtonpost.com/2011/12/08/smithfield-gestation-crates_n_1136567.html" target="_hplink">end its practice of using gestation crates</a> for pregnant hogs by 2017.