This photo, provided by Fort Recovery Equity, Inc. shows chickens inside a new open cage chicken facility in Fort Recovery, Ohio. on Sept. 11, 2007. In the background are the nest boxes covered by red plastic flaps to give the chickens a dark area that encourages egg-laying. (AP Photo/Fort Recovery Equity, Inc.) (Jerry Knapke - AP)

Three months earlier, the same barn housed nearly four times as many chickens, but they were confined to small wire cages stacked on top of each other.

Egg farms are increasing their production of cage-free eggs, spending hundreds of thousands of dollars to convert barns by tearing out cages, installing new floors, reconfiguring feed and water lines, and changing ventilation systems.

"It's a growing market," said Jerry Knapke, operations manager for Fort Recovery Equity, the nation's ninth-largest egg producer. "We see a slow, steady growth."

Knapke doesn't expect cage-free to ever make up the majority of eggs produced in the U.S. However, he projects that 5 percent of the 6.5 million birds raised by the company's 60 contract farms will be cage-free within the next six months.