An animal rights group Tuesday released an undercover video taken at a major Minnesota hog producer, Christensen Farms, heating up a growing national debate over housing conditions for pregnant pigs.

The video shot by Mercy for Animals at Christensen Farms' hog barn in Hanska, a south-central Minnesota town, shows sows in gestation crates, a commonly used pen in the hog industry.

The video was specifically aimed at getting one of Christensen's major customers, Costco, to end the use of gestation crates in its supply system, and on Tuesday Costco sent a missive to its suppliers encouraging them to phase out gestation crates by 2022.

Mercy for Animals commended Costco for its action, though a Costco spokesman said the timing of the letter was not predicated by the video.

Groups championing humane treatment of animals say gestation pens leave pigs with very little room to move. Pork producers say the crates, standard equipment for at least two decades, keep sows from fighting each other.

But pressure from animal rights groups -- often accompanied by undercover videos -- has helped prompt many major restaurant chains and food companies to call for a phase-out of gestation crates, particularly over the past year.

Matt Rice, Mercy for Animals' investigations director, said the Christensen Farms video shows "abuse and cruelty." But in a news release, Sleepy Eye, Minn.-based Christensen said the video depicts no exceptions to the company's -- or the pork industry's -- standards for humane treatment.

"We are committed to taking proper care of our animals," CEO Robert Christensen said in the statement. "Over the years, we have continually challenged ourselves to improve our operational procedures involving the humane and ethical treatment of animals."

Christensen says on its website that it is the largest family-owned swine producer in the country, with 1,200 employees and hog operations in six states. With 162,500 sows, the firm alone would place fifth in Successful Farming's 2011 ranking of the nation's "pork powerhouses."

Details of the video

The video was shot by a Christensen worker over 10 weeks ending in March. Narrated by celebrity and animal rights advocate Bob Barker, the video also shows piglets getting their tails and testicles removed without painkillers, a standard industry practice. Piglets otherwise commonly bite the tails off other piglets.

The video also depicts the practice of killing sick or weak pigs by slamming their heads against the floor. While "manual blunt force trauma" is accepted by the American Association of Swine Veterinarians, Christensen says that earlier this year it adopted carbon dioxide-based euthanasia for sick piglets.

"We are in the process of switching, and while lots of farms have switched, this particular farm has not," said Brian Foster, a spokesman for Christensen.

The video marks the second surreptitious recording in Minnesota by Mercy for Animals within the past year. In November, the group released a video of conditions in hen houses owned by Litchfield, Minn.-based Sparboe Farms, one of the nation's largest egg producers.

After the video came out, McDonald's and Minneapolis-based Target, a major grocery, quickly dropped Sparboe as a supplier. The video showed a worker swinging a hen by a chain -- as well as hen housing that's common in the egg industry.

As with hen cages, animal rights advocates argue that sow housing is too cramped. In gestation crates, sows "can't turn around and can barely take a step forward," Rice said. "Animals with legs should be given the freedom to walk and exercise."

Brian Buhr, a University of Minnesota economics professor, said the gestation crate system was developed to protect pregnant pigs from each other.

"Sows tend to be hierarchical and will fight during gestation," he said. "It's like most animals -- if you pen two dogs together they'll fight for territory and space, and it's the same for swine."

Animal rights groups have fought against gestation crates for years, and more recently the issue has been taken up by some consumers. The issue has increasingly caught the eye of food companies.

In February, McDonald's said it would begin working with its pork suppliers, including Minnetonka-based Cargill, to phase out gestation crates. The fast-food giant's announcement was followed by similar pledges from other restaurant chains.

Cargill's operations are already 50 percent gestation-crate free, according to the Humane Society of the United States. Austin, Minn.-based Hormel Foods announced earlier this year that it would phase out gestation crates at its company-owned operations by 2017.

However, the switch from gestation crates to group hog housing will entail a substantial industry investment that would raise pork prices for consumers, according to a 2010 paper written by Buhr and funded by the National Pork Board.

Nine U.S. states have passed laws prohibiting gestation crates, though none of them is among the nation's biggest hog producers. Meanwhile, Iowa and Utah earlier this year criminalized the taking of undercover animal videos. A so-called "ag-gag" bill was introduced in Minnesota in 2011, but failed.

Mike Hughlett • 612-673-7003