Scientific research on pig enrichment has produced a robust evidence base for what types of environmental enrichment genuinely improve pig welfare — and what falls short of meeting their needs.
The science of pig enrichment is clear: pigs have strong behavioral drives to root, chew, and investigate, and environments that frustrate these drives cause chronic stress and injurious behaviors. The failure of chain-and-rubber-toy "enrichment" to meet pig needs has been demonstrated repeatedly in research — these objects do not satisfy rootable material drives. Straw and other organic substrates that pigs can root through, chew, and manipulate are qualitatively different. The policy gap between what research shows pigs need and what regulations require (and farms provide) remains enormous. Better enrichment standards — mandating rooting materials rather than merely "manipulable material" — would dramatically improve welfare for hundreds of millions of pigs.