The experiment was performed on two batches of animals, being born either in December 2013 (9 l) or in January 2014 (10 l). Materials and Methods Animals and Rearing Conditions We hypothesized that: (1) tail docking is a stressful and painful practice that modifies piglets' behavioral activity, tail, and ear posture shortly after the event, (2) pain and stress are maintained in the weeks following the practice and should lead to modifications of behavior including tail posture and movements or general activity, and (3) docked piglets will develop fear reactions toward humans in the weeks following the event. The aim of the present study was to determine the consequences of tail docking on behavioral activity until weaning. Indeed, piglets may associate the negative states (fear and pain) due to docking with human presence and thus develop fear of humans, as has been observed after castration ( 12). In addition, as docking involves human intervention, human-animal relationship could be affected. To our knowledge, no study has attempted to observe behavioral signs of pain in the weeks following tail docking. Most studies have focused on the tail biting consequences of not docking the tail ( 11) and not on the painful consequences of docking. However, only a few studies have evaluated these consequences. The presence of neuromas detected at slaughter ( 4, 9, 10) suggests the existence of longer term consequences. Reports of the expression of pain-like behaviors (including scooting, jamming, and hunching) in the 120 min following the procedure are not consistent: some studies observed an increase in these behaviors ( 7) while other did not ( 8). In the following minutes, tail wagging, tail movements, and the time spent sitting increase ( 5– 7). Piglets struggle more during the procedure than sham operated animals ( 5) and they vocalize more and at higher frequencies ( 5– 7). The tail is sensitive, as it is innervated ( 4), and there is some evidence of immediate pain and stress consequent on tail docking. However, according to EU regulations it should not be used routinely ( 3). Tail docking is commonly performed to prevent tail biting in pigs as it reduces its prevalence 2–4 fold ( 1, 2). On the other hand, the presence of tail lesions shows that undocked piglets are subject to more tail biting, even before weaning. Present data indicate signs of acute pain and stress in piglets due to docking during the procedure itself and adverse consequences throughout lactation thereafter, including on their relationship with humans. In the human test, D piglets interacted later with an unfamiliar human than U piglets ( P = 0.01, n = 18/group). Between D11 and D25, U piglets had higher scores for tail damage and damage freshness than D piglets (0.09 < P < 0.02) whereas tear-stain score was similar. Between D6 and D26, D piglets kept their tail immobile ( P < 0.001) and in a horizontal position ( P < 0.01) more often than U piglets ( n = 45–47). Just after docking, D piglets held their ears in a posture perpendicular to the head-tail axis and changed their ear posture more often ( P < 0.05). During the procedure, D piglets screamed more and with a higher intensity ( P < 0.05) than S piglets ( n = 48–50). A 5-min motionless human test was performed on D14. Tail damage and tear staining were scored on D5, D11, D18, and D25. Piglets from the D and U groups were observed on D6, D12, D19, and D26 in their home pen for oral behavior, body, and tail posture. Piglets from the three treatments were observed in their home pen after docking on D0 and D3 afternoon for body posture, tail posture and movements. Piglets from the D and S groups were observed during the procedure (body movements and vocalizations) and just after, in isolation, during 20 s for body, tail and ear postures as well as ear movements. Within 19 litters, piglets (1–3 days of age) were submitted on day 0 (D0) to docking with a cautery iron (D), sham-docking (S), or no docking (U). We investigated the consequences of this practice on behavioral indicators of pain and stress, and on the human-piglet relationship during lactation. Tail docking is widely performed in pig farms to prevent tail biting. PEGASE, INRA, AGROCAMPUS OUEST, Saint Gilles, France.Céline Tallet * Marine Rakotomahandry Sabine Herlemont Armelle Prunier
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