Eggs are about to get more expensive, as California moves to make sure hen houses are roomy enough to allow the birds to lay down, stand up, extend their wings and dance around.

Farmers nationwide who want to continue selling to the most populous U.S. state are moving to comply with a new law, taking effect next month, that requires the larger cages. They either must build more hen houses, or house fewer birds in the ones they have, raising their costs.

Wholesale egg prices already average a record $2.27 a dozen nationally, up 34 percent from a year earlier. With the new law, the price Californians pay may jump as much as 20 percent for shell eggs in three to six months, according to Dermot J. Hayes, an agribusiness professor at Iowa State University in Ames. The rest of the country will probably follow suit, he said.

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