Scientific evidence for pig enrichment has expanded substantially — specific enrichment types show measurably different welfare outcomes, enabling evidence-based selection over token provision.
The enrichment evidence for pigs has progressed from simply providing anything to discriminating between enrichment types based on their welfare value. Hanging chains — the dominant compliance response to EU enrichment requirements — provide minimal welfare benefit compared to rooting substrates, yet remain the most common enrichment in European pig systems precisely because they are cheap and easy to manage. This gap between regulatory intent and welfare outcome demonstrates why compliance-based frameworks produce inadequate results without specifying enrichment quality criteria. The science is clear: rooting substrates that allow foraging behavior produce the greatest welfare improvements, measured through reduced cortisol, lower abnormal behavior rates, and more positive cognitive bias scores. Rotation to maintain novelty is essential — pigs that habituate to unchanging enrichment show behavioral responses equivalent to no enrichment. Evidence-based enrichment should be the regulatory standard rather than token provision of any manipulable material.