Dust bathing is a highly motivated behaviour in laying hens with clear biological functions. Its systematic denial in cage systems — and its inadequate provision in many cage-free systems — represents a major and pervasive welfare gap.
Dust bathing welfare is well-established as a genuine welfare need rather than a luxury preference. The finding that hens perform vacuum dust bathing in the absence of substrate — spending time and energy going through the full behavioural sequence on bare wire — demonstrates motivational pressure that cannot be extinguished by denying substrate. In the absence of appropriate dust bathing, hens show lipid accumulation in feathers that reduces insulating properties and may predispose to ectoparasite loads. The welfare harm of dust bathing deprivation is cumulative — hens cannot engage in this behaviour for their entire productive life in cage systems, representing a sustained welfare deficit experienced by billions of hens in conventional cage production globally. Even in cage-free systems, effective dust bathing provision requires maintained litter quality — wet, compacted, or soiled litter fails to support the behaviour, creating de facto deprivation even in systems nominally providing substrate access.