Beneath them, conveyor belts whisk away excrement as 1.2 million eggs travel from hen to carton each day without touching a human hand.

California voters will decide next month whether this kind of operation shows factory farming at its most efficient - or the cruel practices of producers concerned only about the bottom line.

If approved Nov. 4, a ballot measure called Proposition 2 would prohibit ranchers from keeping chickens, veal calves and breeding pigs in pens or cages too small for the animal to move. It is the farthest-reaching measure dealing with farm-animal treatment ever put before voters in any state.

Ranchers would have to ensure that their animals can stand, turn around or stretch.

But since producers have voluntarily phased out the caging of newborn calves and breeding sows, debate over the measure has centered primarily on California's 19 million egg-laying chickens, 90 percent of which are housed in so-called battery cages like the ones at J.S. West.

The restrictions would take effect in 2015, with violations carrying a $1,000 fine.

Major egg producers oppose the initiative and insist the current method of mass production is the most efficient way to deliver inexpensive eggs. They warn that if voters approve Proposition 2, egg producers will move out of state or across the border.

'More expensive eggs'

"Even if I had money to make all of the changes, we would not be competitive with the rest of the nation," company president Jill Benson said. "Eggs would be outsourced. We don't have the consumers for more expensive eggs."

Opponents have raised nearly $7.5 million, including donations of $100,000 or more from at least 15 poultry producers. Two of the largest donors to the anti-initiative campaign face an unrelated federal inquiry into alleged egg price-fixing.

Supporters have raised nearly the same amount, including $3.8 million from the Humane Society. Individuals donated most of the rest.

Jennifer Fearing of the Yes on 2 campaign compared the chicken cages to spending "your entire life on an elevator with eight other people."

The California initiative would be the first in the United States to include battery cages used to house egg-laying hens, which are being phased out across the European Union because of cruelty concerns.

'What chickens want'

Supporters of Proposition 2 say it will give small egg-farming operations a better chance to compete. But large egg producers argue that the small farms cannot meet California's demand for an inexpensive source of protein. Even the large producers can meet only two-thirds of California's demand, Benson said.

State law already requires that animals in enclosed areas have adequate food and water, plus room to move freely.

"I do not perceive that there is suffering," said Julie Buckner, who heads Californians for SAFE Food, which is fighting the proposition.

Benson, the egg company president, said the health of their hens was of foremost concern to farmers.

"Ask them how they know our chickens are unhappy," Benson said. "They're making emotionally based decisions about what chickens want."

About 10 percent of California's eggs are produced by cage-free hens, and Benson's operation is no exception. Although specialty eggs are the largest-growing segment of the market, producers say demand for the more expensive cage-free eggs has not kept up with supply.