Behaviour of two genotypes of growing-finishing in three different housing systems

This trial compared the behaviour of 720 growing-finishing pigs, progeny of either indoor (Large White × Landrace) or outdoor (part-Meishan or part-Duroc) sows mated to Large White boars, when housed in either outdoor paddocks, straw yards or fully-slatted pens. Space allowance per pig in outdoor paddocks, straw yards and fully-slatted pens was 19.98, 1.63 and 0.55 m², respectively with a group size of 20. Pigs were fed ad libitum from an average of 30-80 kg liveweight. Pig behaviour was observed during daylight for a total of 6 h, using both individual (focal) and group (scan) sampling. There were relatively few differences in behaviour between genotypes, although the outdoor genotype spent a higher proportion of observations in straw yards and fully-slatted pens engaged in social activity (P < 0.05) compared to the indoor genotype. Pigs housed in straw yards spent significantly more time examining the floor and moving (P < 0.001), and significantly less time tail-biting (P < 0.01) compared to those housed in fully-slatted pens, where a larger proportion of observation time was spent lying inactive (P < 0.001). Pigs in outdoor paddocks spent a large proportion of observation time inside the shelter hut (0.69), where it was not possible to determine their behaviour, although rooting and exploring the floor was the most frequently observed behaviour when the pigs were outside. Interaction between genotype and housing system did not occur to any major degree. It was concluded that, for the housing systems used in this study, pig behaviour was enriched and welfare enhanced in straw yards compared to fully-slatted pens. Further research is needed, however, before any conclusions can be made regarding the behaviour of pigs in outdoor paddocks.