Despite legal requirements for pig enrichment across the EU, significant evidence gaps remain about what enrichment types are most effective for different pig ages, systems, and welfare outcomes.
The pig enrichment research field illustrates both how far welfare science has come and how much remains unknown. We know with confidence that pigs need substrate for rooting, that inadequate enrichment increases aggression and tail biting, and that some substrates are more effective than others. What we know less well is how to provide genuinely satisfying enrichment within commercial production constraints, how to account for individual variation in enrichment preferences, and how enrichment affects positive welfare states rather than just reducing negative ones. These evidence gaps matter because they limit the ability of welfare standards to prescribe genuinely effective enrichment rather than welfare theater - materials that technically meet requirements without meeting pigs' behavioral needs.