Behavioural Responses of Two Japanese Quail Lines Differing in Body Weight to Heat Stress

The objectives of this experiment were to study the effects of different environmental temperatures during the rearing phase on the heat tolerance and behavioral responses of two Japanese quail lines to heat stress. A total of 192 chicks from two lines were randomly distributed between eight brooding cages. Each line was divided into 4 treatments. Each treatment was different in experimental period of exposure to 35°C heat (2, 3, 4 and 5 weeks after that the temperature was reduced to 25°C). The behavioral traits were determined during the first 5 weeks of age. Also, temperature preference test was done and rectal and leg temperatures and latency until panting were determined after 10 weeks from the starting of the experiment. Results indicated that birds under heat stress changed their behavior significantly. They tended to spend more time sitting and less time standing, walking and feeding. Increase of environmental temperature during the rearing phase leads to an increase in the heat tolerance in Japanese quail. The light quail line was more active and tolerated heat better than the heavy quail line under heat stress. The results obtained could contribute new aspects to a better understanding of thermo-regulative process in Japanese quail. It can allow for developing of new housing and production systems that are more suitable for a specific climatic condition.