A one-time screening of Newcastle disease HI antibodies before slaughter as an indicator of vaccine performance in broiler chicken
2012
Suriani M. N. | Maizan M. | Ong, G. H. | Azizah D. | Sharifah S. H. | Hassuzana K.
Seven poultry farms participated in a study to determine the vaccine performance in broilers vaccinated with Newcastle disease (ND) vaccines following each of the farms own vaccination programmes and procedures. It is foreseen that knowledge of the antibody titres attained by the birds, will help poultry farmers or veterinarians to reflect on all routine procedures taken in their farms in ensuring that the vaccines delivered performed accordingly. The HI antibody titres of a batch of broilers before slaughter may provide these farmers a guide to assist them with future vaccination strategies for their farms. In this preliminary study, just before marketing, at the age of 27-37 days old, 15-20 broilers were submitted for post vaccination HI antibody determination and protection study. The HI-GMT of antibodies of broilers at approximately one month post–vaccination (pre-challenged) titres for five of the farms were below standard, ranging from as low as 1.83 to 4.70 and is associated with its low level of protection afforded i.e. as low as 38-76 %. For three farms, The HI-GMT antibodies were 115.36 and 78.8 and 6.8 and the protection afforded were 100%, 95% and 85% respectively. The lowest percentage of protection afforded were 38% and 44% in chickens vaccinated with killed vaccines at 3 days old. For the seven farms, at total of 122 broilers were screened and challenged, and out of these, 44 birds showed HI titres of <2. Out of these 44 birds, 41% however, survived the challenge.
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