ANIMAL-RIGHTS activists have a sense of zeal that makes them compare themselves to abolitionists, suffragists and civil-rights marchers.
But even though millions of Americans have at least dabbled with vegetarianism, the activists are rarely taken seriously by food companies or federal regulators when they ask people nicely to stop eating meat or wearing leather or going to the circus.
And when some lash out, the whole movement is tainted by association. ''Guerrilla activism'' can be as relatively harmless as throwing red paint on women in fur coats, as risky as opening the cages in mink ranches or as violent as making death threats to a scientist who uses cats to study AIDS.
One group, the Animal Liberation Front, which advocates bombing and is believed to have burned down a horse slaughterhouse, is considered a domestic terrorist organization by the Federal Bureau of Investigation.
But last week, another group, People for the Ethical Treatment of Animals, managed to be taken seriously -- not by being violent but because of wanton violence on the other side. The group, known as PETA, has fought a long legal battle with Kentucky Fried Chicken, trying to push it to give its chickens larger cages, stop forcing the birds to grow so fast that their legs collapse and to gas them so they die painlessly before their throats are slit.
PETA released videotapes from a hidden camera planted by a member who worked undercover in a West Virginia slaughterhouse for eight months. Instead of recording the normal unpleasantries of factory farming, like chickens with their beaks burned off or unwanted male chicks ground up alive into fertilizer, it recorded wanton cruelty: workers stomping on live chickens, and flinging dozens into a wall. The investigator said his co-workers tore the head off a chicken to write graffiti, strangled a chicken with a latex glove, squeezed birds till they exploded and committed ''hundreds'' of other acts of cruelty.
This time, the corporate response was rapid. Yum Brands, the parent company of the KFC Corporation, called the tape appalling, sent in inspectors and told the plant, owned by the Pilgrim's Pride Corporation, to clean up its act or lose its contract. Pilgrim's Pride fired 11 workers and managers and said it would make everyone at its 25 plants sign promises to treat animals humanely. PETA said it wanted people involved to be prosecuted and asked Congress to change the Humane Methods of Slaughter Act to include poultry. It was supported by the Humane Society, which has eight million members and calls itself ''a mainstream voice for animals.''
Groups that do not consider themselves mainstream were pleasantly surprised by the corporate response.
Paul Shapiro, campaign director for Compassion Over Killing, said the usual response to undercover footage was denial. Recently, when one of his teams trespassed on a Maryland egg farm to film dying hens, he said, the farm claimed the footage was forged -- though his members had documented their presence at the site by filming a Global Positioning System indicator, a morning newspaper and some of the farm's mail.
Most Americans do not want to know too much about how their food is made, Mr. Shapiro said, so mere proof that animals are abused rarely makes the news. ''There has to be a criminal conviction, or consumer fraud or corporate hypocrisy, or a great personal story,'' he said. Fraud made the egg farm newsworthy, he said -- its eggs carried ''Animal Care Certified'' labels.
Even a journalist covering animal rights can struggle to be taken seriously. This one was kidded for exposing ''Kentucky Fried Chicken's Abu Ghraib.''
PETA is a champion at getting attention. Donna Marie Artuso, vice president of the National Association for Biomedical Research, which defends the use of animals in laboratories, said that Ingrid Newkirk, PETA's founder, had ''never condemned violent behavior by animal extremists.''
PETA is best known for its comic, sexualized approach to acts that it sees no humor in. It recruits nude supermodels for ''I'd Rather Go Naked Than Wear Fur'' billboards. Its GoVeg.com Web site has films of bikini-clad Playmates wrestling in tofu.
Ms. Newkirk says she want to cut through the silence that surrounds each animal's frightened life journey from egg to plate. ''I've stood on slaughter floors for chickens, for horses in Texas and for dogs in Taiwan,'' she said. ''They all smell the blood. They all have eyes as wide as saucers. They're all asking 'Why is this happening to me?' What we're asking is that they render them senseless first. Why is that such a challenging idea?''