This study designed to know the immuno suppressor effect of aflatoxins and the efficacy of levamisole to reduce these effects in the titer of antibodies and protection against challenge for Newcastle disease vaccine in chickens. This trail include three groups. first group fed on ration free from aflatoxins contamination. Second group fed on ration contaminated with aflatoxins. https://herbsdailyes.shop/product-category/l-tryptophan/