Environmental enrichment for pigs reduces harmful behaviors and improves welfare, and the science of what works is increasingly well-understood.
Pig enrichment research has moved from demonstrating that enrichment matters to identifying what specifically works. The fundamental principle is that enrichment must engage the pig's rooting and foraging motivational systems - materials that allow actual manipulation and exploration, not just novelty, are most effective. Straw provides excellent enrichment because it allows rooting behavior and can be physically moved and scattered; a hanging chain in a barren pen provides novelty but doesn't engage the same behavioral systems as effectively. The quantity and renewal rate of enrichment matters as much as the type - pigs need sufficient material to express their behavior and become habituated to static objects quickly. Practical constraints of commercial farming have driven research into cost-effective enrichment that can realistically be implemented at scale.