Thermoregulatory Responses of Chicks (Gallus domesticus) to Low Ambient Temperatures at an Early Age1

ABSTRACT The potential to induce improved thermo-tolerance in broiler chickens is of great importance. Ther-mal conditioning is one of the management tools used to improve thermotolerance, enabling broilers to cope with extreme environmental conditions. This study investi-gated the effects of exposing chicks to low ambient tem-perature (Ta) on-chick body (Tb), surface (Ts) temperatures and total sensible heat loss (SHL) by convection and radia-tion from the body and from 2 main radiative organs, the face and the legs. At 3, 4, or at both 3 and 4 d of age, chicks were exposed to 5°C for 1.5 h a day (to avoid mortality) or to 10 or 15°C for 3 h a day. In general, in all treatments, the results during exposure to cold differed significantly from the control. A second cold exposure (on d 4 after a first exposure on d 3) clearly enhanced the chicks ’ ability to maintain on-chick body surface tempera-tures during exposure to 15°C and to recover much faste