Egg farmers and the Humane Society of the United States on Monday announced proposed federal legislation that eventually would require larger cages for laying hens.

The legislation, H.R. 3798, would increase the size of the typical cage within 18 years from 67 square inches to 144 square inches for brown hens — and slightly less for white hens. In California, farmers would have to meet that higher standard in 2015, based on a state initiative that voters approved in 2008.

The Humane Society and the national United Egg Producers agreed last summer to seek the law.

Arnie Riebli, a Petaluma egg producer and president of the Association of California Egg Farmers, said his group supports the proposal, but other farm organizations likely will oppose the federal government regulating such animal welfare practices.

Farmers need to grasp that younger Americans have different attitudes about how their food is produced, he said.

"Either you change with it or you become a dinosaur," Riebli said.