Behaviour of ewes and lambs in response to human emotional odours

This study investigated whether sheep (Ovis aries) discriminate the body odour of unfamiliar humans subjected to a contrastive emotion-inducing procedure. Axillary secretions were collected from 38 humans after they watched fearful or joyful films. The behavioural responses of adult ewes (n = 35) and 6-day-old lambs (n = 22) to these odours were assessed using a habituation-dishabituation paradigm validated in this species. Both ewes and lambs exhibited habituation (reduced tactile-olfactory investigation), but no significant dishabituation, limiting strong conclusions about odour discrimination. However, ewes displayed ear postures suggestive of differential emotional reactivity to assumed valence, but these effects were subtle and potentially influenced by test conditions. The lambs exposed to fear odour (FO), relative to those exposed to joy odour (JO), showed increased escape attempts and oral grasping of the odour pad, a conflicting pattern of responses that complicates interpreting FO as aversive. In sum, these results suggest that lambs may react to FO as a distinct stimulus, but they may not clearly associate it with negative valence. Ewes showed behavioural differences in response to odours, yet the absence of clear dishabituation makes it difficult to confirm discrimination ability. Further research including physiological measures is needed to clarify ovine perception of human emotional odours.