Research note: broiler acclimation to heat distress and feed intake effects on body temperature in birds exposed to thermoneutral and high ambient temperatures.

Relationships between ambient temperature, bird acclimation to cycling temperature, heat distress, and feed consumption were evaluated in two experiments. In the first experiment, birds previously acclimated to cycling temperature heat distress (24 to 35 C) for two 24-h cycles were observed to have 24% lower (P less than .01) feed consumption than birds previously housed at 24 C and experiencing their first heat distress exposure. A significant (P less than .01) acclimation history by ambient temperature interaction was detected, with acclimated birds having a higher rectal temperature (42.3 versus 41.2 C) when housed at 24 C and a lower rectal temperature (44.2 versus 44.6 C) when exposed to 35 C than did the unacclimated controls. In the second experiment, feed intake and acclimation effects were separated by precision-feeding birds 0, 5, and 10% of body weight. Rectal temperature in the 24 C and 35 C environments increased linearly (P less than .01) as feeding level increased for both acclimated and unacclimated birds. Similar to the first experiment, an ambient temperature by acclimation history interaction was detected (P less than .01), with acclimated birds exhibiting increased body temperature when housed in thermoneutral environments and lower body temperature when exposed to high ambient temperature distress.(ABSTRACT TRUNCATED AT 250 WORDS)