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Tanzania Veterinary Journal

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Seroimmune responses to strategic vaccination in chickens against Newcastle disease using commercially available vaccines

I.J. Mengele, P.L.M Msoffe

Abstract


Evaluation of the Newcastle Disease (ND) antibody level after different vaccination strategies using I-2 and La Sota Vaccines was experimentally conducted on broiler chicken using standard HI test. Three vaccination strategies employed were 12.5%, 25% and 50% of the chickens were vaccinated; positive and negative control groups were used. At 12.5% vaccination strategy, for I-2 vaccine, 12.5% of the chickens were sero-converted to protective level (HI titre results≥log3base 2) and was not significantly different (p>0.05) to the negative control group. For La sota vaccine 62.5% of the chickens seroconverted to protective level and was not significantly different (p>0.05) compared to control positive group.At this strategy, La sota vaccine has proved to do better than I-2 vaccine in activating humoral immune response.At 25%vaccination strategy, I-2 vaccine has shown that, 75% of the chickens were seroconverted to protective level, the results was significantly different (p<0.05) to the negative control group. La sota likewise, 75% of the chickens were seroconverted to protective level which was significantly different (p<0.05) to the negative control. At this strategy, both vaccines have the same activation. At 50% vaccination strategy, for I-2 vaccine, 81% of the chickens were seroconverted to protective level and for La sota Vaccine, 94% of the chickens were seroconverted to protective level. For both vaccines their results were significantly different (p<0.05) to negative control. At this strategy, both vaccines have similar effect in humoral immune response activation. Therefore vaccinating 25% and above of the chickens will results in a flock immunity in intensive farming.

Key words: Chicken, Newcastle disease, vaccination, La sota




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