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Background and Objective: Newcastle disease (ND) is a viral disease of economic importance in poultry industry worldwide. This study was conducted to investigate the antiviral potential of n-hexane leaf extract from Phyllanthus amarus (P. amarus).
Methodology: A hundred and twenty day old broiler chickens were purchased and raised for the experiment. At four weeks, the birds were randomly assigned into 12 groups of 10 birds each. Chickens in groups 1, 2, 3, and 4 were vaccinated while those in 5, 6, 7, and 8 were left unvaccinated. Groups 9 and 10 served as the positive controls while 11 and 12 as the negative controls. All groups except the negative control were infected. To study the prophylactic effect of the extract, chickens in groups 1 and 5 received 250 mg/l while those in groups 2 and 6 received 500 mg/l of leaf extract for fourteen days before experimental infection. The chickens in groups 3 and 7 received 250 mg/l while those in groups 4 and 8 received 500 mg/l of leaf extract for fourteen days after infection with ND virus to assess the therapeutic effect of the extract. Clinical signs, bodyweight changes and mortality rates were documented. Antibody titers against the virus were determined and postmortem examination was conducted.
Results: Results revealed reduction in mortality rates following administration of the n-hexane extract after the challenge. Prophylactic administration of the extract was more effective in reducing the mortality rates of birds due to the virus infection compared to the therapeutic administration. Similarly, antibody titers decreased in a dosage dependent pattern in the prophylactic group.
Conclusion: These findings indicate that the n-hexane leaf extract from P. amarus has significant antiviral potentials against ND virus in broiler chickens and that prophylactic administration at 500 mg/l might be a safer approach in utilization of the leaf extract against Newcastle disease.