Comparative Study of Chick Embryo and Post Hatching Vaccination Against Newcastle Disease

Abstract

Two hundred and fourty chick embryos were used in this study were divided into four equal groups and incubated. The first group was vaccinated with N.D. vaccine at age of 18 days of incubation. The fourth group was injected with sterile phosphate buffered saline and was considered as a control group up to end of experiment. The second and third groups were left without vaccination until hatching. After hatching fifty chicks of each group were taken as follow, the first group which were vaccinated by in ovo-vaccination methods, the second were vaccinated by spraying at one-day age with ND vaccine followed two times of vaccination at ten and twenty days of age, the third group was vaccinated by spraying method at one-day age then it was vaccinated at age of 7-days with oil inactivated N.D. vaccine. The control group was left without vaccination. The result showed that the vaccine which used in ovo-vaccination had not revealed any negative effect upon the percentage of hatchability rate or upon livability of vaccinated chicks during the first week after hatching. Test of haemagglutination-inhibition (HI) and ELISA were held to define the weekly antibodies levels at 1,7,14,28 for the fourth groups challenge test also was carried onto measure the immunological level for the fourth groups at age of 35 days by using the local isolated velogenic N.D.V. of the affected chicks which given by ocular, nose and oral routs. The result of (HI) test showed that the 3rd group was significantly (P<0.01) higher in the level of (HI) titer before the challenge test compare with first group and fourth and showed significantly (P<0.05) higher of HI titer then the second these result were adapted with the results of ELISA test. The results of challenge test showed that the protection rate of the 3rd group significantly (P<0.01) exceeded upon the 4th group which gave 90% of the protection rate and the 1st and 2nd groups had highly (P<0.01) significant protection rate compared with 4th group which they get the same rate of protection 70% at the challenge test whereas the 4th group (control) gave 10%of the protection rate in the challenge test. The study showed that vaccination by oil inactivated vaccine proceeded by a life attenuated vaccine by coarse spraying at one day age was the best method and gave a higher immunological levels comparing with other groups.