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

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