Burger King yesterday became the first major U.S. fast-food chain to pledge that, by 2017, all of its eggs and pork will come from cage-free chickens and pigs.

The move by the hamburger chain helps it satisfy growing demand among customers for humanely produced fare and adds fuel to an industrywide shift to consider animal welfare when purchasing food supplies.

"There's no question in my mind, especially on the heels of pink slime and BPA, that everyone in the food world is very concerned about consumer reaction," said food industry analyst Phil Lempert, referring to the beef-based food additive and the chemical used in plastic bottles and canned food.

"Even if you're buying a burger, you want to buy it from someone you like and respect," said Lempert, who writes a daily industry newsletter. "It's proven that consumers are willing to pay a little bit more for fairness, whether it's to humans or animals."

Conventionally raised eggs come from hens confined in "battery cages," which give them roughly the same space as a sheet of standard notebook paper. Most pork comes from sows confined during their four-month pregnancies in narrow crates.

The hens would still be housed in a barn, but they would have room to roam and perches and nesting boxes. Sows are also held indoors, but they would not be confined in the cramped crates while they are pregnant. -- AP

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