title: Aggression and affiliation during social conflict in pigs.
abstract: Social conflict is mostly studied in relation to aggression. A more integral approach, including aggressive and affiliative behaviour as well as physiology, may however give a better understanding of the animals' experience during social conflict. The experience of social conflict may also be reflected in the spatial distribution between conspecifics. The objective was to assess the relationship between behaviour, physiology, and spatial integration in pigs (Sus scrofa) during social conflict. Hereto, 64 groups of pigs (9 wk of age) were studied in a 24 h regrouping test whereby pairs of familiar pigs were grouped with 2 unfamiliar pairs, in either barren or straw-enriched housing. Data on aggressive and affiliative behaviour, skin lesions, body weight, and haptoglobin could be summarized into three principal component analysis factors. These three factors were analysed in relation to spatial integration, i.e. inter-individual distances and lying in body contact. Pigs stayed up to 24 h after encounter in closer proximity to the familiar pig than to unfamiliar pigs. Pigs with a high factor 1 score were more inactive, gave little social nosing, had many skin lesions and a high body weight. They tended to space further away from the familiar pig (b = 1.9 cm; P = 0.08) and unfamiliar ones (b = 0.7 cm; P = 0.05). Pigs that were involved in much aggression (factor 2), and that had a strong increase in haptoglobin (factor 3), tended to be relatively most far away from unfamiliar pigs (b = 0.03 times further; P = 0.08). Results on lying in body contact were coherent with results on distances. Pigs in enriched housing spaced further apart than pigs in barren housing (P<0.001). The combined analysis of measures revealed animals that may either promote or slow down group cohesion, which may not have become clear from single parameters. This emphasizes the importance of an integral approach to social conflict.
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands; Animal Breeding and Genomics Centre, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands.
authors.forename: Irene
authors.initials: I
authors.lastname: Camerlink
authors.affiliation: SRUC, Edinburgh, United Kingdom.
authors.forename: Simon P
authors.initials: SP
authors.lastname: Turner
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands; Animal Behaviour & Welfare, Wageningen UR Livestock Research, Wageningen, The Netherlands.
authors.forename: Winanda W
authors.initials: WW
authors.lastname: Ursinus
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands.
authors.forename: Inonge
authors.initials: I
authors.lastname: Reimert
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, Wageningen, The Netherlands.
authors.forename: J Elizabeth
authors.initials: JE
authors.lastname: Bolhuis
mesh_terms: D000374:Aggression; D000822:Animal Husbandry; D000818:Animals; D001522:Behavior, Animal; D001835:Body Weight; D005260:Female; D006242:Haptoglobins / Q000032:analysis; D006799:Housing, Animal; D008297:Male; D034421:Sus scrofa / Q000097:blood / Q000502:physiology*
chemical_list: D006242:Haptoglobins