In what animal-welfare advocates are describing as a "historic advance," Burger King, the world's second-largest hamburger chain, said Tuesday that it would begin buying eggs and pork from suppliers that did not confine their animals in cages and crates.

The company said that it would also favor suppliers of chickens that use gas, or "controlled-atmospheric stunning," rather than electric shocks, to knock birds unconscious before slaughter. It is considered a more humane method, though only a few slaughterhouses use it.

Source