Effect of vitamin E and C on the growth and immunocompetence of coloured birds during summer

The influence of vitamin E and/or vitamin C supplementation on growth, immunity, carcass traits and lymphoid organs of coloured chicks during summer was studied. Coloured broiler chicks (n=540) divided into 9 treatment groups were fed basal diet with supplementation of vitamin E (250 mg or 500 mg) and vitamin C (250 mg or 500 mg) either alone or in combinations from 0–56 days of age. The treatment-wise supplementation to the basal diet was, T₁: control without supplementation, T₂: E 250 mg, T₃: E 500 mg, T₄: C 250 mg, T₅: C 500 mg, T₆: E 250 mg+C 500 mg, T₇: E 500 mg+C 250 mg, T₈: E 250 mg+C 500 mg, T₉: E 500 mg+C 500 mg/kg feed. The average highest temperature and relative humidity during the experimental period was 37.98°C and 87.9%, respectively. The growth rate, feed conversion ratio, humoral, cell mediated immunity and carcass characteristics were determined. Higher body weight and better FCR (P<0.05) were seen in groups supplemented with both the vitamins i.e. T₆, T₇, T₈ and T₉ than individual vitamin supplementated (T₂, T₃, T₄ and T₅) and control group; but no effect on feed intake was observed. Better humoral immunity as shown by higher (P<0.05) haemagglutination inhibition titre against Newcastle Disease vaccine and against sheep red blood cells and higher cell mediated as reflected by increased (P<0.05) cutaneous basophilic hypersensitivity response was seen in T₇ (E 500 mg+C 250 mg) and T₈ (E 250 mg+C 500 mg), groups. From the results, it was concluded that supplementation of vitamin E @500 mg/kg and C @250 mg/kg in the diet of coloured broilers improved growth performance, increased both celluar and humoral immune response during summer stress.