Let’s look at another example tied to housing laying hens. In conventional systems, hens are housed in barns in multi-level rows of cages. In cage-free systems, hens can move within sections of a barn with perches, nesting boxes and floors covered with a natural material.
A multi-year study showed the hens in cage-free systems were able to better express natural behaviors such as pecking and scratching, had better leg strength and improved feather condition, attributes highly valued by some stakeholders. The same study showed the cage-free system had higher mortality and increased cannibalism/aggression (more than twice as many hens died prematurely), increased greenhouse gas emissions (double the ammonia emissions), poorer air quality for workers (particulate matter levels sometimes 8-to-10 times higher) and higher consumer egg prices (cost of production 36% higher).