Immunomodulatory effects of aqueous extracts of Azadirachta indica and Piper Guineense on Newcastle disease vaccination in cockrels

Abstract

The increased incidence of Newcastle disease (ND) outbreaks in the country even amongst vaccinated flocks, has given rise to the search for other means of boosting the immune system besides vaccination alone. A lot of plants have been shown to possess antimicrobial, antipyretic and anticoccidial effects. This study was designed to evaluate the immunomodulatory effect of the aqueous extracts of the leaves of Piper guineense and Azadirachta indica (Neem) on immune response to Newcastle vaccination in birds. A total of 110 cockrels were used in this study (30 for acute toxicity test and 80 for immuonomodulatory effects of extracts). The 80 cockerels were divided into four groups (A, B, C and D), each consisting 20 birds. Group A and B were treated with 100mg/kg of the aqueous extracts of Azadirachta indica and Piper guineense respectively for the first three weeks. All the birds in groups A to C were vaccinated with Newcastle disease vaccine Lasota (NDV-L) at day 21, while Group D was given distilled water only. Blood samples were taken from all groups on day 1, 7, 14 and 21 post-vaccination. Serum antibody level against ND virus were measured by HI test and antibody titre was found to be significantly (p≤0.05) higher in the group treated with Azadirachta indica but low in those treated with Piper guineense. There was no significant (p≥0.05) difference in the immune response seen in Group A compared to the positive control (Group C), but significantly (p≤0.05) higher compared to the negative control (Group D). It was therefore concluded that the aqueous extract of Azadirachta indica may enhance immunomodulatory effects against Newcastle disease virus, unlike that of Piper guineense.