The laboratory assessment of common Newcastle disease vaccination regimes in use in Nigerian poultry

This study was designed to determine the evaluation of different Newcastle disease vaccination regime using the Lasota strain in chickens. Fifty cockerels were divided into four groups with different vaccination regimen for each group which consisted of 15 birds except the control that had 10 birds group1 was vaccinated on day 7 only, group 11 was vaccinated on day 7 and day 2 1, group 111 was vaccinated only on day 21 and the control group was not vaccinated. The birds were challenged by a field strain around day 30. The birds were bled at day old and then weekly from the first week throughout the course of experiment. The haem agglutination inhibition test was used to ascertain the titer level. The result showed that the mean geometric titer GMT of the birds at day old was high and uniform (11.8) in all the birds, the antibody titres declined on day 16 with peak recorded in groups 1 and 11 at day 30 while group 111 and control further declined at day 23 before peaking at day 30. In all the groups, there was a sharp decline in the GMT in group 1 at day 58 and gradual decline in other groups. Clinical signs of Newcastle disease were observed in all the groups. These signs included ruffled feathers, depression, greenish diarrhea and death. Weight loss was more pronounced in the control group than others. Group 1-111 had 80-87% protection whereas the control group had 60% protection. At postmortem, the carcasses from the group including the control had congested lungs, petechial hemorrhages on the proventricular glands, jejunum and cecal tonsils. The effect of the field outbreak was less severe in group 11. The vaccination regimen employed in group 11 was found to be the most protective and economical of all the different regimes used in this study.