Evaluating complementary effects of ethanol extract of propolis with the probiotic on growth performance, immune response and serum metabolites in male broiler chickens

• Ethanolic extract of propolis reduced growth performance attributes such as body weight and feed intake.
• Propolis alone and with probiotics increased immune organs’ relative weight such as spleen and bursa of fabricius.
• Combination of propolis and probiotic improved the antibody titer to Newcastle Disease virus.

The aim of this study was to evaluate the effects of propolis (a natural resinous substance that bees collect from different sources of plants) extract alone or in combination with probiotics on the growth performance and immune response of male broiler chickens. A total of 256 broiler chickens were randomly assigned to 4 treatments: maize-soybean meal basal diet with no supplement as control, the basal diet containing propolis (0.20 g/kg), probiotic (0.45 g/kg), or a combination of propolis (0.20 g/kg) and probiotic (0.45 g/kg). Each treatment consisted of 4 replicated pens with 16 broiler chickens per pen. Broiler chickens had ad libitum access to feed and water and the light program was 23 h light/1 h dark. The inclusion of propolis extract decreased (P<0.05) body weight and feed intake. Propolis extract alone or in combination with probiotic increased (P<0.05) the relative spleen weight in broiler chickens at 42 d of age compared to the control and probiotic. The relative weight of bursa of Fabricius was greater (P<0.05) in broiler chickens receiving probiotics, propolis extract, or their combination compared to those fed the control diet. Supplementation of diet with probiotic, propolis extract, or a combination of both caused an increase (P<0.05) in the concentration of antibody titer to Newcastle Disease virus. In conclusion, supplementation of the diet with propolis extract decreased the body weight of broiler chickens, however, inclusion of propolis, probiotic, and their combination in the diet caused an immunomodulatory effect in broiler chickens.