Lower redness of the facial skin is a marker of a positive human-hen relationship

International audienceIn certain mammals, facial expressions are reliable markers of the emotional state of an individual. In humans andparrots, emotional stimuli can induce a rapid change of face colour that is linked to blood flow. The aim of this studywas to test whether the redness of the face in domestic hens could be used as an emotional marker in the context of thehuman-hen relationship. Two groups of hens (Sussex) were studied: a group habituated to a human with daily positiveinteraction (n=13) and a non-habituated group (n=12). Behaviour and skin colour of wattles, cheeks, ear lobes andcomb were analysed from two video-recorded tests (novel environment and reactivity to human tests) conducted after5 and 6 weeks of habituation. In the novel environment test, usually used for testing general underlying fearfulness,the hens were tested alone in an unknown environment. In the reactivity to human test, the hens were tested againin this environment but with the familiar human sitting inside. The human presence should only be stressful for thenon-habituated group. As expected, the behaviour of the two groups did not differ during the novel environment test.During the reactivity to human test, the habituated hens were more relaxed than the non-habituated hens: they tooktheir first step faster (P=0.03), came faster into contact with the human (P=0.03), explored him longer (P=0.0003)and displayed more comfort behaviours (P=0.01). Face redness differed between the two groups during only thereactivity to human test: lower redness was observed in habituated hens for 3 out of the 4 regions (wattles P=0.01,cheeks P<0.0001, ear lobes P=0.0003). These results show that more relaxed hens are less red, thus face rednesscould be a reliable marker of the quality of the human-hen relationship. As such, it could be used as a tool for humanto infer the emotional state of hens and more broadly, to evaluate their welfare

Exploration of skin redness and immunoglobulin A as markers of the affective states of hens

International audienceNon-invasive markers of affective states can help understanding animals' perception of situations and improving their welfare. These markers are scarce in avian species. In this study, we investigate the potential relation between alterations in facial skin redness in hens and their corresponding affective states. Six hens were filmed in both naturally unfolding scenarios and controlled tests designed to elicit various affective states. The facial skin redness was measured from images extracted from the videos. Our observations revealed that hens exhibited the highest degree of facial skin redness in negative situations of high arousal, a high redness in positive situations of high arousal, and the lowest in positive situations of low arousal. In a second study, we further examined whether facial skin redness and secretory immunoglobulin A (S-IgA) can serve as markers for the quality of the human-animal relationship. Two groups of hens, one habituated to humans (n=13) and one non-habituated (n=12), were compared for general fearfulness in an open field test and for fear of humans in a reactivity to human test. In the open-field test, there were no statistical differences in general fearfulness, facial skin redness or S-IgA concentrations between both groups. However, habituated hens exhibited significantly lower fearfulness and facial skin redness in the presence of humans compared to non-habituated hens in the reactivity to human test. Additionally, habituated hens showed significant lower S-IgA concentration in lachrymal fluid in the presence of humans, with no significant differences in saliva or cloacal samples. We propose that changes in facial skin redness reflect variations in affective states and can be used as a marker for assessing the quality of the human-hen relationship. The relationship between S-IgA concentrations and affective states requires further investigation