An HSUS Report: Welfare Issues with Cage and Cage-Free Egg Production:
A Review of Mortality

. . . Some proponents of battery cages claim that cage-free housing causes unacceptable mortality rates. For instance, Wegmans Food Markets officials have defended their use of cage systems by claiming, “Free-range chickens, exposed to the outdoors, have a normal mortality rate anywhere from 20 to 40 percent a year.”
. . .
In fact, normal mortality rates in free-range flocks are between 5 to 15 percent—less than the mortality rates in many molted, caged flocks. No scientific evidence exists to support the claim that flocks kept in barn aviaries have any higher mortality than flocks kept in cages, after controlling for breed and beak-trimming. Indeed, according to poultry welfare expert Dr. Joy Mench, a professor in the Department of Animal Science at the University of California, Davis, and a specialist who serves on advisory committees for both the United Egg Producers and McDonald’s [and Wegmans], “Mortality and disease rates can be similar under both systems if management is good.”