This investigation was carried out in the Poultry Research Farm, Department of Poultry Production, Faculty of Agriculture, Menoufia University, Shibin El- Kom, Egypt on Norfa chickens to study the possibility of using immunity level of chicks and its relation with heat shock protein 70 concentrations to predict the ability of chicken (older age) to tolerate the future exposure to heat or cold stress (acute and chronic) as well as studying the changes induced in some physiological and productive traits under the levels of immunity and both cold and heat stresses .
Birds with high immunity levels exposed to cold stress for 6 hours as well as which exposed to high temperature stress for 6 days recorded the highest values of Hsp70 (0.056±0.0045, 0.086±0.0031, respectively) compared with the other groups.The levels of red cell characters (RBCs, Hb, PCV, MCH and MCHC) increased as the exposure periods increased from 3 to 6 days in both heat and cold stress cases in both high and low immunity groups. Birds with high immunity levels exposed to heat and cold stresses for 3 hours recorded the highest values in white blood cell measurements (WBCs), Neutrophil (N), lymphocytes (L), heterophils: Lymphocytes (H / L), Monocyte (M) Esinophil (E) and Monocyte (B). There were significant differences between cold and heat stress for T3 and T3 / T4 Ratio, while no significant differences were observed between the different heat stress groups for T4 and ACTH hormones. High-immunity and cold-stressed birds for 3 and 6 days recorded significant differences in GOT and GPT enzymes compared to other groups. Significant differences were found in the RR respiratory rate among high-immunity, high-temperature birds for periods of 3 and 6 hours, as well as for low-temperature groups of 3 and 6 days. The mortality rate increased with increasing the exposure periods to low and high temperature for low-immunity birds. Significant differences were recorded in body weight at 16, 20 and 36 weeks for high and low-immunity birds subjected to cold stress and high temperature stress. The number of eggs produced within 90 days (EN90) and 42 weeks (EN42) and egg weight at EWM decreased with increasing the exposure periods of cold and heat stresses from 3 to 6 days in both low and high immunity birds.