How oral stereotypies including bar-biting develop in pigs, what they indicate about welfare, and the management changes that prevent and reduce them.
Pig oral stereotypies are behavioral indicators of chronic welfare failure — they develop when pigs cannot express fundamental feeding and rooting behaviours, and once established they reflect permanent changes in neural circuits that drive the behaviour even after conditions improve. Prevention is therefore paramount: pigs provided with appropriate enrichment and social conditions from early life rarely develop stereotypies. Management that waits for stereotypies to develop before addressing welfare has already failed. The welfare community increasingly uses stereotypy prevalence as a negative welfare outcome indicator in farm assessment.