When considering “basic behavioural needs”, most people would agree that pigs (and other farm animals) need not only food and water, but also to perform feeding and drinking behaviour; need not only shelter, but also security; need contact with other pigs because they are socially-living animals; need some kind of occupation; need the possibility of grooming themselves; and need to be protected against too much stress. However, this list remains incomplete as long as the need for exploration is left out. The term “exploration” is used for active gathering of information by increased locomotion and by increased use of the senses. Many authorities agree that exploratory behaviour can be as intense and as persistent as feeding or sexual behaviour. Exploration can be induced by endogenous and exogenous factors. If the environment becomes less comfortable, exploratory behaviour is elicited, especially the locomotory components of it. We used to call this “restlessness”. In intensive husbandry systems, as well as in other farming systems, the environment cannot be maintained at an optimal level all the time. For example, intensive husbandry systems are extremely susceptible to ventilation deficiencies, due to high stocking densities. Other departures from the optimum may be brought about by feeding only once on Sundays, restriction of water supply, etc. Now, on the one hand we are keeping pigs in intensive husbandry systems, highly susceptible to disturbances of the environment, and thereby triggering exploratory behaviour, but on the other hand we do not allow these pigs any substrate for this behavioural need, keeping the environment as barren as possible. In such situations one can observe pigs redirecting their need for exploratory behaviour towards other pigs and start ing to gnaw, nibble and root on their pen-mates. This may even lead to can-