Analysis of agonistic interactions between sows with different rank position during mixing

Abstract. Ninety-six sows in twelve groups of eight sows were continuously video-observed during 48 hours after weaning and mixing. The occurrence and the outcome of all agonistic interactions (AI) were recorded and data of wins and defeats were transformed into a 8 × 8 (winner-loser) matrix. Aggressor and receiver of the attacks and fights in the dyads have been determined and the rank index for each sow was calculated leading to the individual rank place RP (1 to 8) and to the classifying into high ranking (HRS: RP 1 to 4) and low ranking sows (LRS: RP 5 to 8). Based on a total number of 2 414 AI dominant sows with RP=1 initiated 94.3 % of the AI they were involved in and were the receiver in 5.7 % of the AI. In contrast, every fourth AI was orientated towards the subdominant sow with RP=8. The sows with RP 7 or 8 were the receivers in nearly half of all AI (44.9 %). Fights occurred more frequently between sows with a low rank place difference. More than 60 % of the attacks and more than 40 % of the fights were initiated from high ranking sows towards low ranking sows even though 28.6 % was the estimated value for those dyads. In only 2 % of the attacks and 18.8 % of the fights LRS engaged HRS which means that HRS usually react with a counter-attack when being attacked by a LRS.