Tail Docking of Piglets 1: Stress Response of Piglets to Tail Docking

SIMPLE SUMMARY: Tail docking is a common industry practice in pork production to reduce tail biting in groups of pigs. Tail biting behaviour involves destructive chewing of the tails of group-mates, which can both compromise pig welfare and cause economic losses. The etiology of tail biting remains poorly understood and potential predisposing factors include crowding, poor ventilation, nutrition and health. This experiment examined the stress response of piglets to two common tail docking procedures: docking with either clippers or cauterisation, surgical castration and a sham handling treatment (handling alone). In comparison to the sham handling treatment, the two tail docking treatments increased the duration of vocalisations and number of escape attempts during treatment, the cortisol response at 15 min post-treatment and the duration of standing with head lowered in the first 60 min post-treatment. However, both these behavioural responses during treatment and the cortisol response at 15 min post-treatment to clippers or cauterisation were lower than that of castration. Piglets in the cauterisation treatment group also had a lower cortisol response at 30 min post-treatment than those in the clipper treatment group. The cortisol and behavioural responses in the tail docking and castration treatments had diminished by 23–24 h post-treatment. ABSTRACT: This experiment compared the stress responses of piglets to tail docking. Two hundred and eighty-eight piglets were allocated to the following treatments at 2 d post-farrowing: (1) sham handling treatment; (2) surgical castration; (3) tail docking using clippers; (4) tail docking using a cauterising iron. Blood samples were collected at 15 min, 30 min and 24 h post-treatment and analysed for total plasma cortisol. Behaviours indicative of pain, such as escape attempts, vocalisations and standing with head lowered were measured. Cortisol concentrations at 15 min post-treatment were higher (p < 0.001) in the tail docking and castration treatment groups than the sham handling treatment group, but at 30 min post-treatment, only the clipper and castration treatment groups had higher (p < 0.001) cortisol concentrations than the sham handling treatment. Duration of vocalisations and escape attempts were greater (p < 0.0001) during the castration treatment than the sham and tail docking treatments, but these behaviours occurred less (p < 0.05) in tail-docked piglets than those that were castrated. Piglets undergoing the tail-docked treatments and the castration treatment exhibited more behaviours indicative of pain, such as standing longer (p < 0.05) with the head lowered in the 60 min after treatment, than those in the sham handling treatment group. There were no treatment effects on cortisol concentrations and behaviour at 23–24 h post-treatment. The physiological results at 30 min post-treatment indicate that tail docking with cauterisation may be less aversive than tail docking with clippers.