EFFECTS OF FAMILIARITY AND RELATEDNESS ON AGONISTIC PAIR RELATIONSHIPS IN NEWLY MIXED DOMESTIC PIGS

The effects of familiarity and relatedness on agonistic pair relations hips (dyads) in different pen regions (pen area or trough area) were s tudied in 16 groups of newly mixed domestic pigs of similar weight (9 pigs per group) at an age of 12 weeks. The agonistic interactions (AI) within 124 familiar (related) and 452 unfamiliar (related and unrelat ed) dyads were continuously recorded for 3 days (10 h daily) after mix ing. Whereas pigs, both in dyads familiar and unfamiliar to each other , showed the same frequency of Al in the trough area, unfamiliar dyads exhibited significantly more Al in the pen area than familiar dyads. The relatedness of unfamiliar dyads had apparently no influence on AI. It is discussed that, besides establishing a dominance hierarchy, pig s react aggressively on strange subjects. Furthermore, the results are briefly discussed with reference to dominance and resource usage in p igs, (C) 1998 Elsevier Science B.V. All rights reserved.