Pig pen design fundamentally shapes welfare outcomes by determining whether pigs can express natural behaviors, access resources, and maintain appropriate social relationships.
Pig pen design is a welfare lever of enormous importance because the physical environment determines what behaviors are possible, what stresses are imposed, and what resource competition exists. A barren, concrete-floored, overcrowded pen where pigs cannot root, explore, or access resources without conflict creates chronic welfare deficits. The design choice that most reflects welfare priorities is substrate provision - deep straw litter transforms the welfare potential of a pen by enabling rooting, creating thermal comfort, and reducing the frustration that drives redirected aggression. The prevalence of tail docking in conventional systems reflects the use of a painful mutilation to compensate for welfare-poor pen design rather than addressing the behavioral need deprivation that causes tail biting.