EFFECT OF DIFFERENT SEASONS ON GROWTH PERFORMANCE, IMMUNE RESPONSES AND ANTIOXIDANT STATUS OF BROILER CHICKENS

The current experiment was carried out in farm nearby Fayoum research station to study effect of different seasons on growth performance of broiler chicks and detect early indicators for supplementing broilers flocks with antioxidant and immune enhancer. Four flocks from Arbor Acres broiler chicks were reared during summer, autumn, winter, and spring seasons in open side system. Productive performance parameters, complete blood count, antibody titers against Newcastle (NDV), antibody titers against avian influenza (H5N1) and some antioxidant parameters were measured. The following results were obtained: Body weight and body weight gain recorded significantly the highest values during spring seasons but the highest (P≤0.05) feed intake value was recorded during winter seasons and the best feed conversion value was recorded during autumn (P≤0.05). Total leukocytes count, heterophilus (H), lymphocyte (L) and H/L ratio were not affected by different seasons. Antibody titers against NDV and H5N1 record the highest significant values during summer season while the worst significant antioxidant status recorded during summer season. In contrast during winter values of antibody titers against NDV and H5N1 were significantly the worst but antioxidant parameters recorded significantly the best values. The results of the current study suggested that during winter flocks may need double doses from NDV and H5N1vaccines. However, during summer and autumn seasons, increasing antioxidant supplementation in diets or even drinking water is recommended.