Many people think a cage-free life is better for hens. It’s not that simple.

Indiana egg farmer John Brunnquell’s 1.3 million hens don’t live in cages. They also get to go outside, making his company, Egg Innovations, the nation’s largest free-range operation in the industry. It wasn’t always so. Brunnquell, 54, grew up on a traditional chicken farm, and he says he “could argue all the benefits of cages.” That changed in the early 1990s, when his first glimpse of a cage-free barn convinced him that the freer system was better for the birds. He spent the next decade overhauling his own.Along the way, he admits, things weren’t always better for his flocks. He had to figure out how to prevent a barn full of newly mobile chickens from pecking, or cannibalizing, each other. He went through seven perching designs to find one that kept the birds from crowding on the floor. He also needed to find ways to lower the rate of a very common injury to laying hens: damage to the keel bone, an extension of the sternum.It was a steep learning curve on a pretty small scale. And it has made Brunnquell worry about the large-scale change now facing the U.S. egg industry, which is racing to meet the demand of hundreds of companies that have pledged to switch to cage-free eggs by 2025. Egg producers and researchers caution that the switch is not as simple as just opening those cage doors — and that mobility brings with it a new set of concerns for chickens’ welfare that most farmers have never confronted. A major 2015 study of three different hen-housing systems found that mortality was highest among birds in cage-free aviaries and that they also had more keel bone problems.