02116nas a2200193   4500000000100000000000100001008004100002260007000043653000800113653002200121653001600143653002700159100001100186700001300197245011000210490000800320520158000328022001401908       2017                            d  c01/2017bSchlütersche Verlagsgesellschaft mbH & Co. KGaHannover10apig10agroup composition10asocial rank10aaggressive interaction1 aM Fels1 aN Kemper00aFighting activity and establishment of a litter-associated dominance order in weaned piglets after mixing0 v1303 aThe aim of this study was to analyse the fighting activity of weaned piglets after mixing, particularly focused on the influence of origin litter on the rank positions achieved by individuals within a group. We formed 16 groups of twelve with either six piglets from two different litters each (6/2) or four piglets from three different litters each (4/3) balanced by weight and sex. Aggressive behaviour between piglets was analysed continuously for the first 72 h after mixing, and an individual rank index was calculated for each piglet. The total number of aggressive interactions differed significantly between both group compositions with piglets in composition 4/3 having more fights than those in composition 6/2 (27.3 fights vs 12.8 fights per piglet, p  lt; 0.05). Piglets fought mainly against non-littermates. High-ranking piglets fought more than middle and low-ranking piglets (24.9 vs 17.3 and 14.5 fights per piglet, p  lt; 0.05) and were more often the aggressors (18.6 vs 5.8 and 2.6 attacks, p  lt; 0.05). In both group compositions, littermates originating from the same litter within a group obtained similar rank positions. We conclude that the number of fights per piglet was affected by the number of litters combined within a group, probably due to the fact that most fights occurred between non-littermates. The social rank achieved by a piglet within a group was significantly affected by its origin litter with some litters being more dominant than others, when mixing an equal number of piglets from two or three different litters after weaning.   a0005-9366