Behavioural and physiological reactions of piglets to gentle tactile interactions vary according to their previous experience with humans

Céline Tallet (1) , Kardiatou Sy (1) , Armelle Prunier (1) , Raymond Nowak (2, 3, 4) , Alain Boissy (5) , Xavier Boivin (5)

1 PEGASE - Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage [Rennes]
2 PRC - Physiologie de la reproduction et des comportements [Nouzilly]
3 Université Francois Rabelais [Tours]
4 Institut Français du Cheval et de l'Equitation
5 UMRH - Unité Mixte de Recherche sur les Herbivores - UMR 1213

Providing piglets with repeated stroking and brushing leads to behaviours of affinity towards their handler, but there is still no evidence of physiological modifications. In addition, other tactile stimulations like scratching have not yet been studied while there are used by pig-keepers. Thus, the present experiment aimed at determining the consequences of stroking and scratching weaned piglets on their later behavioural, cortisol and cardiac responses to human presence and gentle tactile interactions. Four groups of four piglets were weaned at 28 days of age (Day 0) and handled twice a day for 10 min, five days a week, from Day 1 to 28. Handling consisted in standing for 30 s, sitting for 1 min and then stroking and scratching each piglet for 2 min. Four groups of four piglets were used as controls and received only the minimal contact for routine husbandry practices. Behavioural reactions to the presence of the handler in the home pen (Day 25) and to her presence and departure in an arena test (Days 26–27) were observed. Behavioural and cardiac responses to the handler’s presence and contact were compared in a test pen (Days 33–35). Salivary cortisol levels were measured in another test pen after 15-min of either contact with the handler or isolation (Days 40–43). In the home pen, handled piglets investigated sooner the handler (P<0.001) and spent more time investigating her than control piglets (P<0.05). In the arena test, handled piglets investigated sooner the handler (P<0.01) and spent more time close to the handler than control ones (P<0.01). Heart rate of the piglets during stroking and scratching did not differ between treatments but the root mean square of successive differences in heart beat intervals was lower in handled than in control piglets when the rear part of the body was scratched (P<0.01). There was no effect of the previous experience with the handler on salivary cortisol levels (P>0.05). Overall this study shows that scratching and stroking piglets during three weeks after weaning changed the way that they interacted with the handler, being more attracted than control piglets. However, there was no clear difference in cardiac reactions to scratching and stroking between handled and control piglets, suggesting that these contacts are perceived positively, regardless of the previous experience. The body region stimulated may be of importance but it needs further investigation.

Domaines: Biologie animale

Céline Tallet, Kardiatou Sy, Armelle Prunier, Raymond Nowak, Alain Boissy, et al.. Behavioural and physiological reactions of piglets to gentle tactile interactions vary according to their previous experience with humans. Livestock Science, 2014, 167, pp.331-341. ⟨10.1016/j.livsci.2014.06.025⟩. ⟨hal-01129853⟩