Do pigs distinguish between situations of different emotional valences during anticipation?
Publication Type: |
Journal Article |
Year of Publication: |
2011 |
Authors: |
Sabrina Imfeld-Mueller, Lea Van Wezemael, Markus Stauffacher, Lorenz Gygax, Edna Hillmann |
Publication/Journal: |
Applied Animal Behaviour Science |
Keywords: |
anticipation, behavior, behaviour, heart rate, pigs, positive and negative emotions, vocalisation |
ISBN: |
01681591 |
Abstract:
An animal’s welfare is strongly affected by its emotional state. Thus, many recent studies have focused on measuring the emotional states and responses of animals. However, there is still a lack of knowledge on assessing positive emotions, although it is widely accepted that positive emotions are needed to ensure good welfare. In the present study, we investigated the physiological and behavioural responses of 16 weaned domestic pigs, Sus scrofa domestica, during anticipation of either a positive or a negative situation. Pigs were conditioned to two different tone sequences, one announcing access to popcorn (positive situation) and the other announcing the task to cross a partially black ramp (negative situation). After a training period, the pigs were tested individually in four trials each of the negative and positive situations. Behavioural and physiological parameters were examined during different phases of the trial. When anticipating the negative situation, the proportion of pigs uttering high-frequency vocalisations was significantly higher (p<0.001), pigs turned around more often (p<0.001) and the latency to move was longer after door opening (p<0.001). However, heart rate, heart rate variability and locomotive activity were not influenced by the valence of the situation but differed depending on the phase (waiting, tone, anticipation and end) of the trial. We concluded that high-frequency vocalisation might be the most sensitive parameter observed in this experiment, reflecting the emotional response of the pigs during anticipation of different situations. Even though no other differences were found, the results indicate that pigs do distinguish between situations of different emotional valences during anticipation. In addition, avoidance behaviour seems to be a suitable parameter with which to assess the valence of a situation for pigs.