Even before the recent salmonella outbreak, America’s egg industry was struggling to fend off another threat: allegations that it was cruel to chickens.

Egg producers are alarmed at efforts to ban small cages for hens, a movement that has gained momentum in an increasing number of states.

The 550 million eggs recalled in connection with the salmonella contamination came from hens housed in industrial-style “battery cages,” in which birds are crammed against one another in a long battery of wire enclosures.

The cages are common throughout the industry but have been targeted by animal-welfare groups as inhumane and unsanitary. But major egg producers say switching to cage-free methods will do little to improve safety and will add to the cost of a dozen eggs by 25 percent.

In California, a new law will eliminate the use of conventional battery cages starting in 2015. Companies tied to the DeCoster family of Iowa, which is at the center of the current salmonella outbreak, helped fund a $9 million effort to defeat the proposal, which was signed by Gov. Arnold Schwarzenegger this summer.

Michigan has also adopted cage limits to take effect in 2019, while less-stringent regulations have been approved in several other states. Ohio announced an agreement between animal-rights activists and industry groups last month that will bar new battery-cage facilities while exempting current operators.

“The cage-free movement is not only about providing a humane environment for animals,” said Paul Shapiro, senior director of the society’s End Factory Farming campaign. “There is also a strong food-safety component as well.”

But the U.S. industry’s top lobbying group, the United Egg Producers, says there is no difference in egg safety between caged or free-range hens. The cooperative-style organization, based in Alpharetta, Ga., represents companies that provide about 85 percent of the 80 billion eggs produced in the United States each year.