Dust bathing and wallowing are strongly motivated behaviours in pigs and poultry that are systematically denied in most commercial systems, causing measurable welfare compromise.
Dust bathing and wallowing represent clear cases where the denial of a strongly motivated species-typical behaviour causes measurable welfare compromise. The performance of dust bathing movements on bare wire floors by hens with no substrate available is a classic welfare indicator of frustrated motivation; the behaviour is performed not because it achieves its function but because the motivation is so strong it must be expressed even when conditions make it futile. For pigs, wallowing serves genuine thermoregulatory functions in addition to behavioural value; pigs without mud access are more vulnerable to heat stress. The welfare improvement from providing appropriate substrate is substantial and achievable at relatively low cost in many systems. The challenge is litter management in poultry, where wet litter creates health risks, but this is an engineering and management problem rather than an insuperable welfare barrier.