Scientific research has moved beyond simply providing pigs with any enrichment to identifying what types of enrichment are most effective at improving welfare outcomes.
The science of pig enrichment has advanced considerably beyond the assumption that any object in a pen constitutes adequate provision. Effective enrichment must match the motivation it is intended to address: pigs have strong rooting drives that require substrate-based or manipulable materials, not smooth metal objects that cannot be rooted into. The distinction between enrichment that merely occupies time and enrichment that genuinely satisfies behavioral needs is crucial. Scientific literature consistently identifies straw, compost, and mixed-substrate bedding as the most effective single interventions for pig welfare — reducing tail biting, aggression, and stereotypic behaviors while improving growth rates and immune function. The economic argument against straw — that it clogs slurry systems — is a design problem with specific housing systems rather than an inherent constraint, and alternative housing designs successfully incorporate substrate. Welfare researchers advocate for enrichment standards that specify both quality and quantity, not just the presence of some object.