AN INACTIVATED NEWCASTLE DISEASE VACCINE PART II: THE EFFICACY OF AN INACTIVATED, EXPERIMENTAL VACCINE ON THE PREVENTION OF NEWCASTLE DISEASE

A comparison of the efficacy of a Newcastle disease (ND), inactivated, experimental vaccine (NDIEV) and a ND, inactivated, commercial vaccine (NDICV) was under taken. Broiler chickens were divided into 5 groups of 112 birds each. All groups, except group 5 which served as unvaccinated controls, were given a live ND vaccine, strain B1 and different inactivated ND vaccines as follows. Groups 1 and 3 were given a NDIEV at 1 and 10 days old. And groups 2 and 4 were given a NDICV at 1 and 10 days old. When 21, 28, and 35 days old, 28 birds from each group were challenged with a ND virus. Sera was collected for HI antibodies, body weight, feed intake, morbidity, mortality, feed conversion rate and economic performance were observed during 21-31, 28-38, and 35-45 day periods. Results showed that HI antibody titers of NDICV were much better compared with those of a NDIEV. HI antibody titers of birds vaccinated at 10 days of age were higher than those of birds vaccinated at 1 day old. Morbidity, mortality, feed conversion rate, and economic performance of group 1 was worse than those of the other vaccinated groups.