Department of Poultry Sciences, Institute of Animal Science, ARO, The Volcani Center, P.O. Box 6, 50250, Bet Dagan, Israel
Abstract:
The influence of short repetitive cold exposure at an early age (cold conditioning—exposure to 15°C for 3 h at 3 and 4 days of age) on chickens’ thermotolerance during cold challenge (15°C) at 21 days of age was examined. The first cold exposure elicited a dramatic decline in body temperature (Tb) and a significant elevation in stress response (plasma corticosterone concentration); the second cold exposure resulted in moderate Tb and stress responses. Thereafter, the corticosterone concentration remained at a significantly lower level. Acute cold challenge of conditioned broilers at 21 days of age revealed better Tb and stress recovery during the first 24 h, and a significantly lower mortality rate thereafter. Conditioned chickens exposed to optimal conditions (22°C) achieved significantly higher body weights than others. It may be concluded that early cold conditioning improves thermotolerance in broiler chickens in later life.