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

摘要

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 A degrees C and 35.12 A +/- 0.22 A degrees 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 A +/- 0.22 A degrees C), radiant heat load (519.38 A +/- 2.22 W m(-2)), and enthalpy (82.74 A +/- 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