Pink slime, the ammonia-treated filler substance made with beef scraps, was once reserved for dog food before corrupted regulators changed the rules. But a recent media firestorm has reignited the controversy, leaving many people asking why the U.S. Department of Agriculture (USDA) does not require groceries, school cafeterias, or restaurants to disclose which products contain the mystery meat. Now with the battle over whether to require companies to disclose which food products contain this substance, it’s worth taking another look at how the pink slime industry is again flexing its lobbying muscle.