The behaviour, welfare, growth performance and meat quality of pigs housed in a deep-litter, large group housing system compared to a conventional confinement system

The behaviour, welfare, growth performance, and meat quality of deep-litter, large group-housed pigs were compared to pigs raised in a conventional housing system. Castrated males were housed from 9 weeks of age in a conventional housing (15 pigs/pen; 1.0 m2/pig) or deep-litter, large group housing system (90 pigs/pen; 1.7 m2/pig). Behavioural observations and stress physiology measurements were conducted at 9, 17 and 22 weeks of age. The willingness of the pigs to approach a novel object was assessed using a standard novel object test at 22 weeks of age. Pigs in the deep-litter, group housing system spent more time (P < 0.05) standing, locomoting, and interacting with their environment compared with contemporaries housed in the conventional system. At 17 weeks but not at 9 or 22 weeks, pigs in the conventional housing engaged in more (P < 0.05) social interactions than deep-litter housed pigs. Salivary cortisol was higher (P < 0.05) in deep-litter pigs compared to conventional pigs at 9 weeks of age but were similar at 17 and 22 weeks of age. Pigs in the deep-litter, large group system exhibited more exploratory behaviour (P < 0.05) compared to conventionally raised pigs in the novel test. Loins from pigs housed in the deep-litter, large group treatment had lower (P < 0.01) loin pH, more (P < 0.05) purge loss, more glucose in purge (P < 0.05) and were lighter in subjective colour (P < 0.05) than loins from conventionally housed pigs. However, there were no significant differences observed in the objective colour measurements of L*, a* and b*. A trained sensory panel detected no differences in tenderness, juiciness or overall desirability of loins from deep-litter or conventionally housed pigs. In this experiment, housing system modified pig behaviour, fearfulness and stress physiology (at 9 weeks of age) but these differences did not negatively impact meat quality.