Effects of rearing conditions on behavioural and physiological responses of pigs to preslaughter handling and mixing at transport

Abstract

The physiological and behavioural responses of slaughter pigs reared in either a barren environment or in an enriched environment (larger pens with straw bedding) to preslaughter handling and mixing at transport were studied. Enriched-reared pigs had higher salivary cortisol concentrations in the home pen before and after transport than barren housed pigs, but at the end of the lairage period salivary cortisol concentrations did not differ between enriched- and barren-housed pigs. In pigs reared in a barren environment, salivary cortisol concentrations increased significantly after transport and being in lairage, as compared to home pen salivary cortisol concentrations. In pigs reared in an enriched environment, salivary cortisol concentrations did not significantly change after any stage of preslaughter handling and transport as compared with home pen salivary cortisol concentrations. In the truck, pigs reared in a barren environment tended to spend more time walking, standing and manipulating other pigs than enriched-reared pigs. Moreover, pigs reared in a barren environment tended to spend more time walking and fighting in lairage than enriched-reared pigs. Results showed that rearing conditions may affect the behavioural and physiological responses of pigs to preslaughter handling and mixing at transport. The tendency for increased manipulation of pen mates and fighting, and the significant increases in salivary cortisol in response to mixing at transport and being in lairage in pigs reared in a barren environment indicate that pigs reared in a barren environment are likely to experience more stress during common preslaughter procedures than pigs reared in an enriched environment. Key words: Behaviour, cortisol, housing conditions, pigs, slaughter