| Summary: | 碩士 === 國立嘉義大學 === 動物科學系研究所 === 105 === The purpose of this study was to investigate the effect of different interval vaccination of combined Newcastle disease and Infectious Bronchitis (ND+IB) live vaccines on the immune response, growth, and egg production performance of laying hens during laying period. After injected inactived ND, IB, and egg drop syndrome vaccine at 17 weeks old, birds were separated to five groups, and arranged to none and spray ND+IB live vaccine once every 6, 8, 10, and 12 weeks, respectively. The antibodies against Newcastle disease (anti-ND) and infectious bronchitis (anti-IB), Heterophil / Lymphocyte ratio (H/L ratio), weight, egg weight, egg production and egg quality were measured. The results showed that hens were not sprayed ND+IB live vaccine during laying period, although there was a high level of anti-ND antibody titers, but showing a large fluctuation, and those anti-IB titers showed a decline. Hens continuous sprayed ND+IB vaccines during the laying period could maintain the anti-ND and the anti-IB antibody titers at high levels, but hens were sprayed every 6 or 8 weeks could maintain anti-ND antibody titers in a relatively stable level. However, a shorter interval of vaccination would cause the H/L ratio to rise. In particular, hens were sprayed ND+IB every 6 weeks interval had lower egg weight, egg shell strength, egg shell thickness, and egg shell weight (P <0.05). It concluded that it is possible to maintain the stability of anti-ND and anti-IB titers, and to avoid affecting egg production, hens should spray live ND+IB vaccines at 8 weeks interval during the laying period.
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