LITTLE ROCK — Animals rights groups on Wednesday called on Bentovnille-based Wal-Mart Stores Inc. and Springdale-based Tyson Foods to stop buying pork from suppliers the groups said keep pigs in cages so small they can barely move.

The group Mercy for Animals held a news conference in Little Rock to discuss Wal-Mart’s use of pork from suppliers such as Christensen Farms in Hanseka, Minn., where pigs are kept in "gestation crates," or cages barely larger than the animals.

Meanwhile, The Humane Society of the United States and SumOfUs.org issued a statement calling on Tyson Foods to stop the use of gestation crates in its pork supply chain.

Mercy for Animals spokeswoman Becca Frye said pigs are intelligent and social animals, but gestation crates prevent them from engaging in the most basic behaviors. Major food providers such as McDonald’s, Burger King, Wendy’s, Kroger and Whole Foods have demanded that their suppliers stop using gestation crates, but Wal-Mart has not, she said.

"This is blatant animal abuse that Wal-Mart should not be supporting," she said.

Frye showed reporters video footage which she said was obtained by an undercover operative who spent 10 weeks late last year and early this year working at Christensen Farms. The video showed pigs biting and beating their heads against the bars of their gestation crates, bleeding from open sores, being castrated and having their tails cut off without anesthetic, and being killed by workers who slammed them head-first into the floor.

Wal-Mart did not immediately return a call to its corporate headquarters Wednesday seeking comment.

Christensen Farms said in a statement Wednesday that the images in the video "are dated and are intentionally taken out of context."

The company said its procedures call for injured pigs to be treated under veterinary supervision. It denied that the video depicted any inhumane treatment.

"Christensen Farms’ animal welfare practices are fully consistent with industry standards for humane and ethical treatment of animals," said Laura Dalquist, a consulting veterinarian for the company.

The Humane Society of the United States and SumOfUs.org said in their statement that nearly 250,000 people have signed a petition calling on Tyson Foods to demand that its suppliers stop using gestation crates.

"Consumer citizens have sent a message that is loud and clear to Tyson’s that they don’t support forcing pigs to spend their lives crammed inside cages so small they can’t even turn around," said Taren Stinebricker-Kauffman, founder and executive director of SomOfUs.org.

Tyson spokesman Worth Sparkman said in an email Wednesday, "Tyson buys hogs from thousands of family farms, many of whom have individual sow housing, some of whom have group pen sow housing. Experts believe both housing systems are humane for the sows when managed properly."

Sparkman said the company is committed to humane animal treatment and has called on the hog farming industry to accelerate research into ways to improve housing and production practices.