Outdoor access for pigs provides the richest available enrichment environment but requires specific management to maximize welfare benefits and minimize risks from disease, weather, and environmental degradation.
Outdoor pig welfare provides evidence that the richest expression of pig behavioral needs requires genuine contact with varied natural substrate rather than indoor substitutes. Outdoor pigs can root in soil, wallow in mud, forage for diverse material, and engage in the full behavioral repertoire shaped by pig evolutionary history. The welfare benefits of outdoor access are comprehensive and mutually reinforcing: rooting substrate, thermoregulation through wallowing, exercise through varied terrain, and cognitive engagement through novel environments all contribute simultaneously. Management challenges are real but surmountable, and outdoor pigs consistently show the best welfare outcomes among commercial production systems.