Rectal temperatures of laying broiler breeder chickens in response to the chronic heat challenge at 32°C over 8 weeks.

<p>In the first week, the rectal temperature of laying broiler breeder chickens in the chronic heat-stressed group (CS) was not elevated by the cyclic environmental temperature (32-35-32°C) and only a tendency of increase in rectal temperature was observed in the second week. After exposed to the consistent 32°C thermal treatment from the third week, CS birds had a significantly higher average body temperature than those in the chronic control group (CC). Values are expressed as means ± SE of data from 10–12 individual birds. * indicates significant differences (P<0.05) between CS (line with squares) and CC (line with diamonds) at the same time of the trial.