Research into the complexity and quality of pig enrichment has moved beyond simple provision to understanding what types of enrichment provide the greatest welfare benefit for the longest time.
Enrichment research has moved from asking whether to provide enrichment to asking what kinds are most beneficial. The evidence points strongly toward materials that can be manipulated, destroyed and explored repeatedly - particularly straw and substrate materials. Enrichment that allows choice and control provides cognitive benefits beyond physical engagement. This research directly informs practical welfare improvements.