The Way Humans Behave Modulates the Emotional State of Piglets

Abstract

The emotional state can influence decision-making under ambiguity. Cognitive bias tests (CBT) proved to be a promising indicator of the affective valence of animals in a context of farm animal welfare. Although it is well-known that humans can influence the intensity of fear and reactions of animals, research on cognitive bias often focusses on housing and management conditions and neglects the role of humans on emotional states of animals. The present study aimed at investigating whether humans can modulate the emotional state of weaned piglets. Fifty-four piglets received a chronic experience with humans: gentle (GEN), rough (ROU) or minimal contact (MIN). Simultaneously, they were individually trained on a go/no-go task to discriminate a positive auditory cue, associated with food reward in a trough, from a negative one, associated with punishments (e.g. water spray). Independently of the treatment (P = 0.82), 59% of piglets completed the training. Successfully trained piglets were then subjected to CBT, including ambiguous cues in presence or absence of a human observer. As hypothesized, GEN piglets showed a positive judgement bias, as shown by their higher percentage of go responses following an ambiguous cue compared to ROU (P = 0.03) and MIN (P = 0.02) piglets, whereas ROU and MIN piglets did not differ (P > 0.10). The presence of an observer during CBT did not modulate the percentage of go responses following an ambiguous cue (P > 0.10). However, regardless of the treatment, piglets spent less time in contact with the trough following positive cues during CBT in which the observer was present than absent (P < 0.0001). This study originally demonstrates that the nature of a chronic experience with humans can induce a judgement bias indicating that the emotional state of farm animals such as piglets can be affected by the way humans interact with them.

Broadcasting human voice to piglets (Sus scrofa domestica) modifies their behavioural reaction to human presence in the home pen and in arena tests

“…This is, to our knowledge, the first time the real consequences of speaking (not directly but through voice broadcast) on the development of the pig-human relationship has been measured. Preceding studies reported only scarcely using human voice during interactions with pigs: some expressed the use of voice (Terlouw and Porcher, 2005;Andersen et al, 2006;Brajon et al, 2015c;Muns et al, 20 2015), others reported being silent (Day et al, 2002;Brajon et al, 2015a), and most publications did not mention vocal interactions, which suggested that they were not used (e.g. Hemsworth et al, 1981;Pearce et al, 1989;Geverink et al, 1998;Pedersen et al, 1998;de Oliveira et al, 2015;Carreras et al, 2017).…”

“…3 emotional state of animals (Schmied et al, 2008;Tallet et al, 2014) and their cognitive abilities (Brajon et al, 2015c), and thus animal welfare (Tallet et al, 2018).…”

“…Animals may become habituated to human presence. Moreover, though speaking gently is often cited in treatments including the gentle tactile handling of animals (Jones, 1993;Lensink et al, 2000;Brajon et al, 2015c), its effects on animal behaviour have not been studied per se, to our knowledge. Thus our study investigates the impact of human presence and human voice on the pig-human relationship.…”

Invited review: Socio-cognitive capacities of goats and their impact on human–animal interactions

“…Negative perceptions of people by farm livestock can substantially reduce their welfare, subsequently impacting upon meat or milk production due to elevated stress levels (Brajon et al, 2015b;Breuer et al, 2000;Hemsworth, 2003). Therefore, an important theoretical consideration for these interactions is whether animals associate specific experiences with certain handlers.…”

Manipulable object and human contact: preferences and modulation of emotional states in weaned piglets

“…They may even induce behavioural reaction similar to those 68 toward social partners (Brajon, Laforest, Bergeron, et al 2015). Regular positive human contacts may even 69 lead to improved welfare through positive cognitive bias (Brajon, Laforest, Schmitt, et al 2015). In addition, 70 pigs raised in a poor environment may develop more interest toward a familiar human than pigs raised in an 71 enriched environment (Tallet et al 2013), leading the author of the study to hypothesize a familiar human may 72 be perceived as an enrichment.…”