The Effects of Components of Grazing System on Welfare of Fattening Pigs

The objective of this study was to clarify the most effective component of grazing for improving welfare of fattening pigs. This study compared welfare indicators of 20 fattening pigs aged 100 to 124 days (the prior period) and 138 to 164 days (the latter period) in an indoor housing system (IS), an outdoor pasturing system (OP), a concrete floor paddock system (CF), a concrete floor paddock system with fresh grass (FG), or a soil floor paddock system (SF). The last three treatments include important components of a grazing system: extra space, grass feed, and soil floor. Behavior, wounds on the body, and performances, measured as average daily gain (ADG) and feed conversion ratio, were observed. CF pigs behaved similarly to IS pigs. FG pigs showed higher levels of foraging, chewing and activity. SF pigs engaged in higher levels of foraging, exploring, activity, and rooting, and showed a similar amount of playing behavior as OP pigs. ADG was the same in all treatments at the prior period, and increased in the order FG, IS, CF, SF, and OP at the latter. The behaviors and performance of SF pigs resembled those of OP which seemed to indicate a consistently higher standard of welfare than the other treatments. In conclusion, the existence of a soil floor is the most important component of a pasture for improving the welfare of pigs.