Growing pigs are observed to spend a considerable amount of time chewing substrates in their environment (e.g. Jensen et al., 1993). This behaviour has been exposed to scientific investigation on many occasions because of its link to the serious welfare problem of tail-biting (see Fraser, 1987). However, there is still no motivational explanation which adequately describes the causation of chewing because it is unclear if the behaviour reflects feeding motivation, exploratory motivation, or a combination of both (Day et al., 1995). Therefore, this aim of this paper was to test the hypothesis that the initial exploratory chewing of a novel substrate may identify nutritional properties which could, if appropriate, reinforce feeding motivation and subsequent foraging behaviour.