Indian Journal of Poultry Science

The present investigation was undertaken to evaluate the immunomodulatory effect of ascorbic acid in broiler chickens vaccinated separately with IBD and ND. The chickens were given ascorbic acid @ 1 g/lit in drinking water once a day starting from 8^th day of age till the period of study. Two positive control groups viz., one reared only on normal basal ration and provided with plain drinking water vaccinated with IBD vaccine and challenged with live virulent IBD virus and other group similarly reared but vaccinated with ND vaccine and challenged with live virulent ND virus were also used. Negative control group comprised of chicks reared on normal basal ration and plain drinking water. The birds of all these groups were challenged with IBD live virulent virus on 46^th day and ND live virulent virus on 66^th day by administering 1 ml and 0.3 ml virus intramuscularly, respectively. The response of ascorbic acid was adjudged on the basis of changes in haematological and assessment of humoral immunity (ELISA) and cell mediated immunity (DTH). There was increase in leukocytes and lymphocytes count but decrease in absolute heterophil count in supplemented birds. Antibody titers against IBD and ND vaccine and DTH were significantly (P≤0.01%) elevated in supplemented groups as compared to control birds. Challenge studies with liver IBD and ND viruses showed 100% protection in ascorbic acid supplemented groups whereas only 75% and 80% protection was observed in IBD and ND virus challenged groups, respectively. In non-vaccinated groups 80% mortality occurred due to ND and 90% birds died due to IBD.