Effects of piglet age on some indicators assessing pain at tail docking, with or without analgesia

Pig tails are often docked at an early age in order to prevent tail biting later on. According to farms, it is carried out in the first two days but may occur later, in combination with other management procedures. An experiment was conducted in order to evaluate the effects of age and analgesia on pain related to tail docking, using different types of indicators. Two day-old piglets were allocated within litter to tail docking after being treated with meloxicam (M, 0.4 mg/kg, IM) or placebo (P) or to sham docking (S) (n=29/treatment). Movements and intensity of vocalisations were recorded during tail docking. Postoperative behaviours (activity, posture, localisation and tail movements) were observed every 2 minutes for an hour at 3 periods: immediately after the procedure, 4 and 24 hours later, for 24 animais per treatment. Blood samples were collected on 18 other piglets per treatment, 30 minutes after the procedure, to measure plasma cortisol. Wound healing was assessed on day 1, day 3 and day S. Piglets were weighed at birth, before the procedure and at weaning. A similar protocol was applied on piglets treated at 5 days of age. Average daily gain from birth to weaning did not differ between treatments (P>O.l) but tended to be higher in D2 than in DS piglets (P=0.1). Cortisol was higher in P than in S pigs (P<O.OS) with M pigs being intermediate. Intensity of vocalisation and body movements during procedures were higher in P and M than in S pigs (P<O.OS). Cortisol level decreased whereas vocalizations and body movements during procedures increased from D2 to DS regardless of treatment (P<0.001). None of the behaviours recorded after the procedure, except being un der the heat lamp and tail movements, differed significantly between treatments. S piglets presented more ample tail movements and Jess trembling tails than P and M (P