Comparison on immunization effect of inactivating of several newcastle disease oil-adjuvant vaccines

The test compared immunization effects of five ND vaccines.The results showed that different antibody levels were observed in the chickens first vaccinated by different ND vaccines.The upswing of the ND antibody titer in the chickens vaccinated by the ND bivalent vaccine was fastest.The ND antibody titer attained the peak 20 d after vaccination.For the chickens vaccinated with the ND bivalent vaccine and the inactivated ND vaccine,the protection rates of vaccinated at 1-day age and attacked with virulent NDV at 14-day age were 5/5 and 4/5,respectively,whereas for the chickens vaccinated with the ND bivalent inactivated vaccine,the inactivated ND vaccine and the imported inactivated ND vaccine,the protection rates of vaccinated at 10-day age or elder,attacked with virulent NDV on 7 or more days after vaccination were 4/5-5/5,2/5-5/5,and 0/5-2/5,respectively.For the chickens inoculated with the ND bivalent vaccine,the imported ND vaccine,and the control group,the positive rates of NDV from the anal swab were 0/5,5/5,and 5/5,respectively.The results suggested that the immunization effect of the ND bivalent vaccine was better than that of the imported ND vaccine and the inactivated virulent ND vaccine and was a little better than that of the inactivated ND vaccine.