Primary replication and tissue distribution of duck plague (duck virus enteritis) virus in domestic ducks following oral infection were studied by an avidin‐biotin‐peroxi‐dase complex (ABC) method of immunoperoxidase staining. The virus replicated primarily in the mucosa of the digestive tract, especially in the oesophagus as early as 24 h after infection, then spread to the bursa of Fabricius, thymus, spleen and liver. The epithelial cells and macrophages of these organs were the principal site of virus replication, although virus antigen was also found in lymphocytes. The antigen was localized both in the nucleus and cytoplasm of these cells.

Background and Aim: Global trend to remove the antibiotic growth promoter (AGP) from animals contributes to the exploration of successful measures to sustain production and reduces the intestinal diseases in the post-AGP era. Plant extracts, therefore, have been used to improve performance and intestinal health. Here, we conducted a study to evaluate the effects of neem (Azadirachta indica) leaf extracts (NLE) as alternatives to AGPs in broiler chickens. Materials and Methods: Sixty day-old broiler chicks were assigned to 12-floor pens, each stocked with five birds and divided into three treatment groups of four pens per treatment. The groups were: Negative control, basal diet without additives; positive control, basal diet with antibiotics and vitamins; and NLE treated group, basal diet supplemented with 0.1% aqua extract of neem leaves. Results: Overall feed intake was significantly (p≤0.05) highest in the positive control. Higher body weight, higher dressing percentage, and lower feed conversion ratio were observed in birds treated with NLE compared to the negative control group (p≤0.05) but not the positive control group (p>0.05). There was no significant variation in hematology between different groups. Furthermore, the economic evaluation indicated that the NLE treatment was found cheaper than control and antibiotic treatment in cost-benefit analysis. Conclusion: We suggest NLE might be a cheaper alternative to antibiotics in broiler production as indicated by improved body weight and feed efficiency.