文摘
Mixing litters of pigs often leads to short- or long-lasting aggression. As social recognition (SR) is important for the development and maintenance of stable social groups, a lack or disruption of SR could prolong agonistic interactions and reduce welfare. Investigations of SR abilities are therefore of considerable importance. However, experimental assessment of SR generally involves moving subjects to unfamiliar environments, or excessive handling, or aggression during the familiarisation period (in which subjects become acquainted prior to testing their ability to recognise each other), which in turn may change the outcome of the test. In this study, we tested a novel method for assessing SR in young pigs aiming to minimise these problems. For the familiarisation procedure, flexible netting was placed between farrowing pens allowing physical contact between litters but preventing unwanted mixing and fighting. We also investigated whether recognition of a familiar individual is affected by relocation to a novel environment. Forty-eight piglets from 12 litters (4 piglets/litter) were tested in a split plot design with litters as the experimental units for comparing two familiarity (familiar/unfamiliar) and three relocation (no relocation/relocation to pens with the same spatial orientation/relocation to pens with a different spatial orientation) treatments. Results indicated that piglets exposed to unfamiliar animals spent more time on social investigation than those exposed to familiar ones, suggesting that SR can be successfully tested using this novel approach. The relocation treatment did not influence the amount of time spent on social investigation, but did affect duration on exploration of the arena. Piglets meeting familiar individuals were more susceptible to this effect after relocation than piglets meeting unfamiliar conspecifics.
