Evaluation of Juvenile body weights, conformation traits and some heat stress parameters in broiler pure lines and crosses under high ambient temperature

An experiment was conducted in broiler pure lines and crosses to evaluate juvenile body weights, conformation traits and some heat stress parameters under high ambient temperature. The ambient temperature of the brooder pens was increased to 38–40°C by providing supplementary heat through halogen lamps. 2 WK body weight was highest in PB-1 followed by PB-2. 4 wk body weight was highest in PB-1X naked neck cross (PN) followed by PB-2. Both 5 WK and 6 WK body weights were highest in PN cross followed by PB-2. Breast angle and shank length were highest in PB-1 followed by PN cross. Significant differences (P<0.01) were found for body weight at all ages and breast angle and shank length at 5 weeks among 6 genetic groups. It indicated that PN cross obtained higher juvenile body weights as compared to other genetic groups. For Lipid Peroxidase (LPO) and Catalase (CAT) non significant differences were observed among 6 genetic groups. For Glutothione peroxidase (GPx), Alkaline Phosphatase (ALP), Superoxide dismutase (SOD) and H: L ratio significant differences were observed among genetic groups. Higher estimates of GPx were found in PN cross. Higher estimate of ALP was found in control broiler. Higher estimates of SOD were found in PB-1. Higher H/L ratio was observed in control broiler. No definite trend of antioxidative enzymes was observed in these genetic groups. It may be concluded that naked neck was least susceptible to heat stress and control broiler was highly susceptible to heat stress condition.