They gathered last week outside supermarkets and shopping malls in Chicago, Minneapolis, Washington and other U.S. cities, carrying signs and posing for TV cameras in goofy-looking cow suits. A young woman in Manhattan dumped a bucket of milk onto a frozen sidewalk. A man in Madison, Wisconsin, dragged white plastic cartons stamped with the skull and crossbones up the steps of the state capitol. Two dozen demonstrators marched in front of Atlanta's Toco Hills shopping center with a banner that read stop the "frankenfood" -- save the cows.
What roused these '60s-style protesters was a quintessentially '90s issue: whether a genetically...