Colony cage systems replaced battery cages in the EU but remain controversial, offering more space and some enrichment while still falling short of full behavioral freedom.
Colony cage systems represent a genuine improvement over battery cages in that hens can express some natural behaviors, but they still severely restrict the range and quality of behavior possible. Keel bone fractures — painful injuries from perch collisions and falls — affect the majority of colony cage hens and represent a major unresolved welfare problem. The welfare debate between colony cages and cage-free systems involves genuine tradeoffs, and research continues to identify which systems best meet the full range of laying hen needs.