Acute heat-stress effects on physiology and fear-related behaviour in red jungle fowl and domestic fowl

Two experiments were conducted to compare heat tolerance of red jungle fowl (RJF) and commercial broilers (CB) at (i) a common age and (ii) a common b ody weight. In exp. 1, RJF and CB of a common age (8 wk) were exposed to 36 +/- 1 degrees C for 6 h. RJF had smaller increases in heterophil to lympho cyte ratios and body temperature and higher serum cholesterol concentration s than CB in response to the heat treatment, while tonic immobility (TI) me asurements were not affected by heat stress. In exp. 2, RJF and CB of a com mon body weight (1000 +/- 150 g) were subjected to similar procedures as in exp. 1 (except TI durations). Both breeds responded similarly to the heat treatment. In both experiments, RJF had higher serum glucose level than CB, and the trait was not affected by heat exposure.