The battery cage has become a symbol of factory farming, and campaigns to replace it with cage-free housing have achieved remarkable success and faced significant resistance.
Battery cages prevent virtually all natural behaviors: dust bathing, wing flapping, perching, nesting, and social maneuvering. The space per bird (67 square centimeters in old EU cages) is less than an A4 sheet of paper. Welfare science is unambiguous that this level of confinement causes suffering. However, cage-free transition is complex: barn systems can have higher disease transmission and behavioral injuries without proper management. The welfare case is for well-managed cage-free systems, not simply the absence of cages. Consumer pressure has been instrumental in driving corporate commitments.