The aim of this study was to examine the effects of roughage and shelter on certain welfare indicators in growing pigs that have access to ample straw and space. The effects of the two treatments were evaluated both by recording the pigs' use of the various areas of the pen and by measuring
the frequency of two specific behaviours, 'aggression' and 'play', that are considered to be significant indicators of welfare in pigs. Seven replicates were used, each involving 96 pigs. The pigs were randomly allocated to eight experimental pens at 10 weeks of age, and were observed from
13 to 22 weeks of age. The two treatments, roughage and shelter. were distributed according to a 2 x 2 design in the pigs' outdoor runs, four of which were located on each side of the barn (north side versus south side). The pigs spent most of their time in the straw-provided areas, and the
frequency of their aggressive behaviour was also the highest in these areas, suggesting that these locations were the most attractive to the pigs. The pigs with access to roughage showed a lower frequency of aggression (P < 0.05) and spent more time in the outdoor area where the roughage
was placed than those pigs with no access to roughage (P < 0.05). No other effects of treatment were found on the length of time spent in the different pen locations. Play frequency decreased with age (P < 0.05) and with increasing temperature (P < 0.01). Moreover, when housed on
the south side of the building, the pigs with access to shelter played more than those without (2.0 versus 1.0 events per hour [SE = 0.3]; P < 0.05); this suggests that the opportunity to regulate the body temperature by use of shade results in improved welfare. In conclusion, the pigs'
behaviour indicated that their welfare was improved by free access to roughage and shelter.