SHOCK-POTENTIATED TONIC IMMOBILITY IN CHICKENS AS A FUNCTION OF POST-HATCH AGE

Socially reared chickens (1, 3, 6, 9, or 12 days posthatch) received 3·0 mA, sham, or no shock immediately before restraint-induced tonic immobility. Immobility durations of unshocked groups were relatively brief and did not change significantly at 1, 3 and 6 days posthatch; increased significantly at 9 days; and did not change from 9 to 12 days posthatch. Shock significantly increased immobility duration at each posthatch age. Immobility durations for shock groups did not differ significantly from each other at 1, 3, or 6 days posthatch; increased significantly at 9 days; and declined significantly from 9 to 12 days posthatch. A second experiment replicated the shock-related increase, peak, and decline in immobility duration using lower shock intensities. © 1979.