Chickens roam the pasture at Alexandre Kids farm in northern California. (Photo Courtesy of Alexandre Kids)

Many of the largest U.S. sellers of organic eggs boast that their hens are vegetarian, and for an increasingly food-curious public, this may be great advertising.

A carton of Eggland’s Best advertises that the company uses “vegetarian fed hens.” Horizon promises that their eggs “come from hens that are fed a 100% organic, vegetarian diet.” Land O Lakes hens have a diet with no animal fat or by-products.

Yet for the chickens, who are natural omnivores that readily devour bugs and small animals when they’re available, the forced vegetarianism can be a disaster.

Chickens on an unsupplemented vegetarian diet typically fall short of an essential protein-based amino acid known as methionine, and without it, they fall ill. Worse, the birds will also turn on each other, pecking at each other in search of nutrients, and these incidents can escalate into a henhouse bloodbath, farmers say.

“They’re really like little raptors - they want meat,” said Blake Alexandre, the owner of a 30,000 chicken operation in far northern California that keeps its birds on pasture. “The idea that they ought to be vegetarians is ridiculous.”

“This is one of those problems caused by the fact that most Americans are so far removed from their food supply,” said Tracy Favre, a farmer and organic inspector who serves on the federal advisory board for organic products. “When I see eggs in the supermarket being advertised as vegetarian this and that, I cringe.”

Now the vegetarian diet for chickens is provoking one of the most contentious issues within the burgeoning world of organic food: How should farmers make sure that their vegetarian birds get enough methionine?

The market for organic eggs and chickens has been expanding rapidly, according to USDA figures. Tens of millions of organic chickens are raised in the U.S. a year, counting both those for laying eggs and those for eating.

The vast majority of those organic chickens are fed a ration of corn and soy beans that is supplemented with a synthetic version of methionine.

That might sound like a reasonable solution. But because this synthetic methionine is not from an organic source - or even a merely natural one - the federal organic program has been limiting how much farmers may feed their flocks. And those limits on artificial methionine, some farmers complain, have now been set so low that they harm the chickens.

“The birds are suffering,” said Ernie Peterson, owner of Cashton Farm Supply based near LaCrosse, Wisc., who testified on Tuesday to federal officials weighing a new policy.

“It’s not right that we are forcing this diet on them,” he said. “We have people who are supposed to worry about animal welfare. Where are they? This is cruelty.”

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Complicating the entire debate are the almost philosophical questions regarding how farmers ought to be treating and feeding chickens. How much space are farmers obligated to give them? How much access to the outdoors? What should they be eating?

Within the organic sphere, farmers are supposed to accommodate the "natural behaviors" of their animals, and such questions draw passionate responses.

In the ideal described by some in the organic movement, the most humane way to raise the chickens is on a pasture rather than in a cramped barn. On pasture, chickens can engage in their natural behavior of scratching at the ground and uncovering bugs - a potentially critical source of protein.

This method of raising chickens is rare, but advocates say the availability of pasture could help resolve the methionine deficit - the birds would get proteins from bugs.

Alexandre, for example, has 30,000 hens on 300 acres of lush green pasture. He has recently been conducting a methionine experiment with a few thousand of his birds - he stopped giving them their normal methionine ration. It’s too early to tell how the birds will fare, he said, but the early results have been encouraging. There has been no detectable change in their behavior or production, he said.

“They’re getting bugs, critters and creepy-crawlers out there,” Alexandre said. “We haven’t noticed any difference.”

But Alexandre’s farm is an exception. Most organic chicken operations have far less space for the birds, less opportunity to reach pasture, and far fewer opportunities to get those extra sources of protein.

Moreover, even if pastures could close the methionine gap, in many regions the weather is too cold for pastures to provide a year-round solution.

That has left organic farmers scrambling for sources. So far, they’ve explored Brazil nuts, insect larvae and fish meal.

What everyone agrees on is that decades ago, raising healthy chickens was easier. In the ‘40s and ‘50s, farmers fed chickens meat scraps, offal and blood and bone meal, they said.

But under current rules for “organic” food, animal feed cannot include mammalian parts, officials said.

Will Harris of White Oak Pastures, a Georgia farm that raises birds, has been experimenting with feeding them the larvae of black soldier flies. The intent, he said, is to more closely mimic what a natural chicken diet might be.

“Chickens are the furthest thing from vegetarians,” Harris said. “That advertising is ridiculous. It’s like people going to the zoo and saying they only want to see the vegetarian tiger.”