Increasing public concern has developed, in recent years, over the welfare of animals in agriculture. One aspect of this is the impact of the barren environments typical of commercial pig production systems, with bare concrete walls and floors, simple rectilinear layout and no objects to manipulate other than troughs and water nipples. The sensory impoverishment inherent in this severely limits the range of experience and behaviours open to pigs and may prevent the display of certain basic ‘behavioural needs’. Possible consequences include boredom, frustration, stress and diversion of energy to destructive activities like aggression.