The purpose of this study is to investigate the safety of neem leaves aqueous extract and its possible ameliorative and protective effects on broiler chickens vaccinated against NDV and experimentally infected with NDV by assessment of biochemical and hematological parameters, besides histopathological changes. A total of 192 Hubbard chicks were divided equally into eight groups (Gp.1 control group, Gp. 2 vaccinated against NDV, Gp. 3 infected with NDV group, Gp. 4 vaccinated+ infected group, Gp.5 neem aqueous extract administered group, Gp.6 vaccinated+ neem aqueous extract administered group, Gp.7 vaccinated+ neem aqueous extract administered group, Gp.8 vaccinated+ infected+ neem extract administered group). After 42 days from starting of experiment, blood and organs samples were collected and biochemical, hematological tests were done beside the histopathological evaluation. Broiler chickens infected only with NDV showed hyperproteinemia, hyperglobulinemia, increasing of serum liver enzymes activities, increasing of serum uric acid and creatinine levels, no significant changes in erythrogram, leukocytosis, lymphocytosis and monocytosis besides histopathological changes in hepatic and renal tissues. The vaccinated group showed some of those changes. Neem extract administered group markedly hypolipidemic with normal values for most parameters with improving to them in combination with vaccination and /or infection. Combining of neem leaves aqueous extract with NDV vaccine and/or ND infection ameliorated most of the deteriorating effects induced by them which appeared in the form of improvement of liver and kidney functions beside stimulating of the immune system. There is a need to be publicized neem aqueous extract as a safe medicinal plant with a wide medicinal benefits in poultry farms.
