Studies on the Immunity Effect of Newcastle Disease Complex Vaccine in One-day Old Common Chick

Four kind of complex vaccines were composed of NDV La Sota strain and the specific antibody against NDV in different ratios,the immunity effect test of vaccines were carried out with one-day old common chicks.Chicks in group 1 to 4 were vaccinated with complex vaccines 1 to 4 respectively,chicks in group 5 were vaccinated with La Sota live vaccine,and chicks in group 6 were not vaccinated with any vaccine.Blood samples were taken post-immunization three weeks,and levels of anti-NDV antibody were tested by HI test.All chickens in group 1 to 6 were challenged with high virulent NDV Beijing strain F48E9 when twenty-one days old.The test results showed that the mean HI antibody titers of group 1 to 6 post-immunization three weeks were 3.2log2,3.1log2,3.3log2,3.2log2,3.1log2、2.9log2,respectively.After challenge,mortality in group 1 to 6 were 15%,20%,0%,35%,30%,50%,respectively.The results suggested that the complex vaccine made with NDV La Sota and anti-NDV antibody could remain good immunogenicity,reduce vaccine virulence and increase vaccine safety,and its immunity effect was better than that of common live vaccine.