Maintaining stable social groups in pig farming dramatically reduces aggression, injury, and chronic stress that result from repeated mixing of unfamiliar pigs.
Social stability is one of the most welfare-significant factors in pig production, yet it is routinely sacrificed for management convenience through repeated mixing of unfamiliar animals. Each mixing event triggers a new hierarchy establishment through fighting that causes injuries, chronic stress, and immune suppression. The welfare and economic case for maintaining stable social groups from birth to slaughter is compelling — better growth, fewer injuries, lower veterinary costs, and reduced tail biting. The barrier is production system design rather than biological feasibility.