Aggression and Affiliation during Social Conflict in Pigs

I. Camerlink, S.P. Turner, W.W. Ursinus, I. Reimert, J.E. Bolhuis

Research output: Contribution to journalArticleAcademicpeer-review

19 Citations (Scopus)


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
Original languageEnglish
Article numbere113502
Number of pages21
JournalPLoS ONE
Issue number11
Publication statusPublished - 2014


  • acute-phase proteins
  • c-reactive protein
  • individual aggressiveness
  • growing pigs
  • interindividual distances
  • dominance relationships
  • agonistic behavior
  • domesticated pigs
  • unacquainted pigs
  • transport stress


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