In many parts of southern China, high environmental temperatures are frequently recorded.
In particular, in Hainan Island, high temperatures occur during three quarters of the year.
Behaviors were recorded in AHS group during the period of heat stress (4×0.5hr=2hr).
In the PHS group, behaviors were observed and recorded at - h, - h, and - h for three consecutive days (3×0.5hr per day).
The heat treatment ceased during the weekends and the effects on the behavior were observed three times daily for three consecutive days.
Changes in the duration of behaviors in response to heat stress of the experimental groups were calculated.
Heat stress has negative effects on poultry performance. (1999) reported that, when external house temperature was high, broiler feed intake, feed conversion ratio, and growth rate were reduced.
In heat-stressed layers, reduced food intake led to a decrease in egg production and reduced egg weight and quality ().
Therefore, poultry often suffer from heat stress, which causes inestimable and negative impacts on their growth, development, production, and reproduction (). While their growth rate is fast, their ability to adapt to the changes in environment conditions is poor.
Moreover, since they do not present sweat glands in the skin, chickens are highly sensitive and vulnerable to heat stress, particularly when they are young.