Outdoor and deep litter pig systems can provide dramatically better welfare than intensive indoor systems, but also present specific welfare challenges including parasite burden and climate vulnerability.
Outdoor pig welfare represents the best commonly available commercial welfare standard, but it is not automatically welfare-positive without appropriate management. Muddy, overstocked outdoor systems with poor shelter create different welfare problems from intensive indoor systems. Welfare-positive outdoor pig production requires rotational grazing to prevent parasite and disease buildup, adequate shade and wallowing in summer, weather protection in winter, and stocking densities that allow genuine expression of natural behaviour. When these conditions are met, outdoor pigs show dramatically better welfare indicators than their indoor counterparts: more positive behaviour, better immune function, and fewer stereotypies.