Distress calls as social stressors affecting chicken welfare

Social signals about current environmental risks can shape development in young animals. Distress calls made by young chickens (Gallus gallus domesticus) may also encode affective state, with high arousal, potentially 'anxiety-like' state characterized by continuous calling, and learned helplessness or potentially 'depression-like' state by a more intermittent pattern. During early life (age 4-7 days), we played chicks artificial stimuli mimicking these two call patterns. Growth effects suggest caller affective state can modulate this social signal: chicks exposed to bouts of 'Continuous' calls grew faster and were heavier by late commercial life (day 43) than Controls. In contrast, chicks exposed to 'Intermittent' calling showed slow, then compensatory, growth. A third experimental treatment with similar 'noisiness' to distress calls did not influence growth. Responses to a late-life social isolation trial suggested lasting impacts on stressor perception or resilience. Comb temperature elevation during isolation, indicating acute stress, was greatest in the Continuous group. Call rate decline during isolation, potentially indicating a tendency towards learned helplessness, was steep in all three experimental treatments; hence, noise-related disturbance from vocalizations may also shape development. Distress calls are consequently an important consideration in farms, where young are raised at high density and one individual is heard by many.