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

摘要

Ninety-six sows in twelve groups of eight sows were continuously video-observed during48 hours after weaning and mixing. The occurrence and the outcome of all agonisticinteractions (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 havebeen determined and the rank index for each sow was calculated leading to theindividual 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 dominantsows with RP=1 initiated 94.3 % of the AI they were involved in and were the receiver in5.7 % of the AI. In contrast, every fourth AI was orientated towards the subdominant sowwith 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. Morethan 60 % of the attacks and more than 40 % of the fights were initiated from highranking sows towards low ranking sows even though 28.6 % was the estimated value forthose dyads. In only 2 % of the attacks and 18.8 % of the fights LRS engaged HRS whichmeans that HRS usually react with a counter-attack when being attacked by a LRS.