Health conditions of two genotypes of growing-finishing pig in three different housing systems: implications for welfare

This trial compared the health and welfare of growing 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. A total of 720 pigs, in groups of 20, were fed ad libitum from an average of 30 to 80 kg liveweight. Welfare was assessed using a combination of different health criteria, to account for adventitious bursitis of the hock, body injuries, stomach ulceration and prevalence of enzootic pneumonia. The outdoor genotype had less body damage and lung damage due to enzootic pneumonia compared to the indoor genotype. In outdoor paddocks and straw yards, pigs had significantly less adventitious bursitis (P<0.01), injuries (P<0.05), stomach ulceration (P<0.001), mortality and morbidity (P<0.01) and lung damage (P=0.074) compared to those in fully-slatted pens. No significant interactions were found between finishing system and genotype for any of the health parameters, and the overall effect of season on pig welfare was unclear due to conflicting health criteria. It was concluded that for the finishing systems used in this study, pig welfare was enhanced in both outdoor paddocks and straw yards compared to fully-slatted pens.