Stereotypic behaviours in pigs — including bar biting and rooting on concrete — are reliable indicators of poor welfare caused by frustrated behavioural motivation.
Stereotypic behaviours in pigs are not harmless quirks — they are scars of chronic frustration that indicate welfare failure. A sow repeatedly biting the bars of her gestation crate is attempting to perform rooting and foraging behaviours that her environment makes impossible. The behaviour becomes self-reinforcing over time through neurological changes that make it persist even after conditions improve. This persistence means that welfare audits cannot rely on absence of stereotypies as a sign that current conditions are adequate — historical deprivation may be recorded in the animal behaviour. The most welfare-positive systems prevent stereotypy development by providing appropriate environments from the outset rather than attempting to rehabilitate already-established behaviours.