Daily variations in the thermoregulatory behaviors of naked neck broilers in an equatorial semi-arid environment

The aim of this study was to evaluate the daily variations in the thermoregulatory behavior of 4- to 6-week-old naked neck broilers (Label Rouge) in an equatorial semi-arid environment. A total of 220 birds were monitored for 5 days starting at 0600 hours and ending at 1800 hours. The period of observation was divided into classes of hours (C _H). The observed behaviors were as follows: feed and water intake, wing-spreading, sitting or lying, and beak-opening. A total of 14,300 behavioral data values were registered. In C _H 2 (0900 hours to 1100 hours) and 3 (1200 hours to 1500 hours), the greatest average body surface temperature was recorded (34.67?±?0.25 °C and 35.12?±?0.22 °C, respectively). The C _H had an effect on the exhibition of all behaviors with the exception of the water intake behavior. Feed intake was more frequent in C _H 1 (0600 hours to 0800 hours) and 4 (1600 hours to 1800 hours). In C _H 2 and 3, the highest frequency of sitting or lying behavior was observed. Beak-opening and wing-spreading behaviors occurred more frequently in C _H 3 where the body surface temperature (35.12?±?0.22 °C), radiant heat load (519.38?±?2.22 W m^?2), and enthalpy (82.74?±?0.36 kJ kg^?1 of dry air) reached maximum recorded averages. Thus, it can be concluded that naked neck broilers adjust their behavior in response to daily variations in the thermal environment. Wing-spreading and beak-opening behaviors are important adaptive responses to the thermal challenges posed by the equatorial semi-arid environment.