Just six companies control two-thirds of the nation’s meat production. It’s time to end their monopoly of our food supply.

The hogs screech as the barn fills with steam. Thousands jostle and shriek. It takes hours, but eventually they quiet and then collapse. By morning, their bodies cover the floor. Survivors snort and squeal weakly through the haze, until two workers, using captive-bolt guns, put them down. At the end, a John Deere track loader is brought in to scoop up carcasses and carry them off.

The video, shot in May on a hidden camera installed by animal rights group Direct Action Everywhere at a rural facility owned by Iowa Select Farms, captures what the meat industry calls “ventilation shutdown plus.” Under this protocol, workers herd animals into an insulated barn, turn off manure pit fans and the outside ventilation system, and then—the “plus”—pump in carbon dioxide and scalding steam. Overnight, temperatures exceed 140 degrees Fahrenheit, as toxic fumes rise and condense in the fog-choked air. The barn becomes a poison sauna. “Animals die,” according to the American Society for the Prevention of Cruelty to Animals, “from some combination of hyperthermia, carbon dioxide, and other gases that quickly accumulate in the barns.”