One of the costs of living in a group is the imposition by certain group members of constraints on the behaviour of others (Mendl and Deag, 1995). This appears to be the case with feeding behaviour where individual pigs show a large number of small meals but group members have fewer larger meals (de Haer and de Vries, 1993). Morgan et al. (1997) found that grouped pigs given straw bedding had more smaller meals than those without, suggesting some alleviation of the group constraint. The aim of this experiment was to investigate if changing straw provision resulted in similar and reversible effects in this behaviour.

120 male pigs (40±0.4kg) were used in three blocks each with 4 pens of 10 pigs. In each block of 42d duration one pen had no straw throughout (treatment A); one pen had no straw for 21d (period 1) followed by straw for 21d (period 2)(B); one pen had straw followed by no straw(C) and one pen had straw throughout (D). The pens were situated in a naturally ventilated building with light from 0600 to 2000h.