Fisher et al. (1985) reported that above 28 -29
DC,chickens will commence panting. The onset
and control of panting require a rise in body
temperature (Richards, 1971), and are mediated by
warm- sensitive neurons in the spinal cord (Barnas
& Rautenberg, 1985). Respiratory frequency and
evaporative water loss are linearly related and do
increase with ambient temperature above the
panting threshold (Geisthovel & Simon, 1984).
These energy-consuming responses in hot
environment could reduce retention of
metabolizable energy, thus reducing growth rate
in birds fed during hotter daylight hours only.
Results for the trial indicate that the various
feeding times exerted significant (P