ENVIRONMENTAL REQUIREMENTS OF PIGS MEASURED BY BEHAVIORAL DEMAND-FUNCTIONS

Individual domestic pigs, Sus scrofa, were given the opportunity in daily test sessions to work on fixed ratio (FR) schedules of reinforcement for access to one of three different commodities (food, contact with a partner animal, and a stimulus change called 'door opening'). The amount of work required for access to each reinforcer was varied systematically by changing the size of the FR schedule (FR 1,2,5,10, 15,20 and 30). Demand curves, analogous to those used in economics, were derived for each commodity. The slopes of these curves were shallowest (inelastic demand) for food, an apparently essential item, and were steepest (more elastic demand) for door opening, an apparently less essential item. Demand functions could be generated for a range of different stimuli and demand elasticity appeared to provide a useful quantitative index of the relative importance of different environmental features to pigs. © 1993 The Association for the Study of Animal Behaviour.