The objective of the present study was to investigate the effectiveness of a non-antibiotic growth promoter (Natusol) which is a combination of phytomolecules, direct-fed microbials (DFMs) and organic acids on performance, serum enzyme activities, immune response and visceral organ weights of commercial broiler chickens. A total of 300 day-old Ross 308 broiler chickens (mixed sex) were obtained from a local hatchery, weighed, and randomly allotted to 4 treatment groups with 5 replicates of 15 birds each. They received different treatments as basal diet (control); control plus 400 mg/kg bacitracin methylene disalicylate (BMD); control plus 0.05% Natusol (Natusol1) and control plus 0.1% Natusol (Natusol2). Chicks fed BMD resulted in maximum feed efficiency and a significant (P ≤ 0.05) increase in the body weight, relative weights of liver, kidney and pancreas and Newcastle disease (ND), Infectious Bursal Disease (IBD) and Avian Influenza (AI) titers at d 42. Dietary inclusion of Natusol at the level of 0.1% into the basal diet proved its efficiency equal to BMD fed chicks, whereas addition of a probiotic at the level of 0.1% showed its applicability similar to the control group. It is concluded that the tested Natusol product at 0.1% but not 0.05% in the current study may be a suitable replacement for BMD in poultry diets.
