Research On The Immune Technology Of Newcastle Disease For Commercial Laying Hens

Newcastle disease(ND) is a common and multiplex disease in poultry farming, and is recognized as one of the diseases difficult to prevent and control. Immunization is the main method to prevent and control this disease, while the key is to keep a strong, lasting, unanimous immunity to ND throughout the raising period. Jinzhou is a city with developed layer farming, acquiring favorable immunity effects in hens is very important. This study was performed to evaluate different types of ND vaccines on immunity effects of commercial laying hens, and based on these results, the best vaccination program was established by screening. The following spread and application of these achievements showed remarkable economic returns and social benefits.The first experiment was conducted to evaluate different types of ND vaccines on immunity effects of commercial laying hens.1000healthy1-day-old chicks were randomly divided into5groups, each with200birds. At8d and43d, chickens in each group were vaccinated with different ND vaccine:Group A, Group B, Group C, Group D were vaccinated with ND attenuated vaccine(C30), Combined ND and Infectious Bronchitis attenuated vaccine, inactivated ND vaccine, C30combined with inactivated ND vaccine, while Group E were used as control. Blood samples were obtained and cloaca swabs were collected every7days before and after the immunization. Antibody levels were measured by methods of GB16550, and reverse transcriptase polymerase chain reaction(RT-PCR) was used to detect virulent and attenuated ND virus. The results showed that average antibody level of Group D was significantly higher(P<0.05) than other groups, and it kept a higher uniformity degree and longer persistent time, meanwhile, the positive rates of both virulent and attenuated virus were extremely lower(P<0.01)than the other groups.The second experiment was performed to establish the best vaccination program.1200healthy1-day-old chicks were randomly divided into3groups(Group A, Group B, Group C), each with400birds and accepted different vaccination programs(Program A, B, C).At8d, chickens in each group were vaccinated with different ND vaccine. Every7days after the immunization,20chickens were randomly selected and blood samples were obtained to determine the antibody titre. The results showed that Group B with the Program B had higher(P<0.05) antibody level and uniformity degree than the other2groups. The detailed measures of program B was taken C30(atomizing, ldose/bird) and inactivated ND vaccine(subcutaneous injection,0.3mL)at7d, C30(atomizing, ldose/bird) at15d, C30(atomizing or eye dropping, ldose/bird) and inactivated ND vaccine(intramuscular injection,0.5mL) at60d,90d,120d. Vaccinations of C30and inactivated ND vaccine every3months afterwards is needed to ensure the immunities.The third experiment was to spread the achieved results to a larger scale.10000healthy1-day-old chicks were randomly divided into5groups, using the best vaccination program established just now. Blood samples (100birds per time and with a total of500birds per experiment) were obtained7d after the first immunization and14d after the second immunization, and then samples were acquired every30days afterwards. The results showed that Group B had higher antibody level (over51og2), and uniformity degree through out the experiment period. Simultaneously Group B had lower morbidity(P<0.05), mortality(P<0.05), and higher laying rate(P<0.05).In conclusion, the best ND vaccination program in Jinzhou was taken C30(atomizing, ldose/bird) and inactivated ND vaccine(subcutaneous injection,0.3mL) at7d, C30(atomizing, ldose/bird) at15d, C30(atomizing or eye dropping, ldose/bird) and inactivated ND vaccine(intramuscular injection,0.5mL) at60d,90d,120d. Vaccinations of C30and inactivated ND vaccine every3months afterwards is needed to ensure the immunities.