As part of a campaign to put pressure on Walmart, Mercy for Animals, an animal rights organization, released harrowing video this week documenting what activists call the torture of pigs by workers at a Minnesota pork farm that supplies the retail chain.

The extremely graphic, distressing video, which also includes explicit language, was recorded by an activist who worked undercover at Rosewood Farm in Pipestone, Minn. The video shows workers slamming piglets into concrete floors until they die, castrating them without painkillers, and roughly beating and cursing at sows. But the more egregious abuse, activists say, is standard industry practice: keeping sows in restrictive gestation crates for their entire lives.

The activist who recorded the video, who did not want to give her name because she is working on another undercover investigation, told The Lede in a telephone interview, “They had thousands of sows that were confined into these tiny gestation crates that were barely larger than their own bodies.” She added that she often found the animals “screaming and banging their heads against the cages,” and “lying in their own excrement, unable to turn around.”

Luke Minion, the chief executive of Pipestone Systems, which owns the Rosewood Farm and others, said in an interview that he fired one employee and reassigned another as a result of the activists’ investigation. “There are things depicted on the video that are not defensible nor are they our policies,” Mr. Minion said. “We want to be better than what’s on that video.”

Mr. Minion, a trained veterinarian, also said that castrating piglets and docking their tails without anesthesia is normal procedure and defended the gestation crates, which he called “individual maternity pens.” The crates, he said, “are an appropriate option.” He added, “We who raise the livestock ought to be able to keep that choice.”

Mercy for Animals reported a worker at the farm to a local judge, who issued a search warrant at the plant, but the Pipestone County attorney declined to file charges after an investigation by the sheriff’s office.

Despite expressing concerns about the video evidence gathered by the activists, Walmart has yet to agree to a change in policy. “We think the animal handling in this video is unacceptable — we are currently conducting our own review of the situation,” said Danit Marquardt, a Walmart spokeswoman. She called gestation crates a more “complicated issue,” and said that Walmart is working toward “an industrywide model that is not only respectful of farmers and animals, but also meets our customers’ expectations for quality and animal safety.”

Matt Rice, Mercy for Animals’ director of investigations, told The Lede that the retail chain was targeted because “Walmart is the largest pork retailer in the country and they’re virtually alone in their continued support for gestation crates.” While Mr. Rice acknowledged that a “majority of pork producers” still use gestation crates, he insisted that their impact on the animals was brutal. After years in a cage that is just two feet wide, he said, pigs begin to “exhibit stereotypic neurotic behavior, such as biting the bars of their cages and smashing their heads against the bars.” The investigator at the Pipestone farm said the farm manager told her that the sows “go so crazy that they start eating their babies.”

In an angry statement calling Mercy for Animals “a front group for the Humane Society of the United States,” the National Pork Producers Council said America’s pork producers “don’t need questionable undercover videos produced by organizations with political agendas to remind them of their commitment to animal care.”

Similar undercover investigations have led to changes in factory-farming in the past. After the Humane Society released distressing video in 2010, showing caged pigs at a farm operated by Smithfield, the pork-producing giant recently acquired by a Chinese company, the company agreed to phase out the practice.

Nine states in the United States have banned the use of these pens, which are outlawed in the European Union, and about 60 companies – including McDonalds, Burger King and Costco – have begun to demand that suppliers stop using gestation crates.

Gov. Chris Christie recently vetoed a bill to ban the crates in New Jersey, a move that may be a sign that Mr. Christie has his eyes set on certain voters in a possible 2016 run for president, Politico reported this week.

As my colleague Natalie Angier reported, a study published in 2009 revealed signs of intelligence in pigs that make them seem more closely related to humans than we might otherwise think. The researchers found that domestic pigs “can quickly learn how mirrors work,” learn to follow a friend that is good at finding food – or ditch a follower trying to mooch – and, if offered, will gladly accept a drink while watching television.

The Mercy for Animals video was edited into a report narrated by the actor James Cromwell, who played the kindly farmer who rejects killing his pig in the film “Babe.” At the very end of the report, the actor suggests that viewers “can help stop animal abuse, by leaving pork off your plate and adopting a vegetarian diet.”

Jeff Johnson, an assistant professor of philosophy at St. Catherine University in St. Paul, has delved into the ethics of meat-eating for the Agriculture, Food and Human Values Society. In an interview this week with a Fox News station in Minneapolis, Mr. Johnson suggested that the practices shown in the Mercy for Animals video raised ethical questions for animal-loving consumers. “If we wouldn’t want these things done to our cats and our dogs,” he asked, “how can we be O.K. with them being done to pigs or cows or chickens?”