?It?s probably going to mean the end of an era in Petaluma,? said Steve Mahrt of Petaluma Farms, an opponent of Proposition 2, which passed with 63 percent support on Nov. 4.

The measure requires most chickens, pigs and veal calves in California to have enough room to turn around freely, lie down, stand up and extend their limbs. The provisions don?t take effect until 2015.

But Mahrt and others in the egg industry said requiring more space per chicken means fewer eggs can be produced, raising the cost of doing business.

They argue that the language of the proposition is unclear, with no specific standards for how chickens must be contained.

?Nobody really knows what it means,? said Arnold Riebli, whose Sunrise Farms operation produces a million eggs a year.

?If the outcome is ?only cage-free,? we?re going out,? Riebli said.

He estimates it would take him $15-$20 million to convert to larger cages and twice that to change to a cage-free operation.

Mahrt, who produces organic eggs, said even his cage-free operation may be affected, if the state requires a certain amount of space per pen based on the number of chickens inside.

His ranch faces up to a two-thirds cut in production, Mahrt said.

However, Prop. 2 supporters, including the Humane Society of the United States, dispute that current cage-free operations would be affected.

?The opposition would have us believe that this means the birds must be able to simultaneously spread their wings,? the supporters? Web site?s ?Myths vs. Facts? section states. ?Even if such a synchronized ballet of wing-spreading were possible, it?s not required by Prop. 2.?

Riebli said despite popular support for the proposition, consumers favor eggs from caged-bird operations because of their lower price.

If California ranches can?t sell eggs for that price anymore, consumers will turn somewhere else, he said.

?There?s a big disconnect between what was voted on and how consumers spend their money,? Riebli said. Encouraging shoppers to buy local eggs ?is easy to say, but it doesn?t happen.?

Studies back that up, showing that 93 percent of eggs sold in California are from caged operations, Mahrt said.

Again, the measure?s supporters dispute farmers? fears, pointing to a similar change in regulations in Arizona, where a voter-approved initiative prompted veal producers throughout the nation to improve their animals? conditions.

Supporters are hoping for a similar shift in the egg industry, but Mahrt remains skeptical.

?It appears they want very limited egg production in California,? he said.

(Contact Corey Young at corey.young@arguscourier.com)