With the rising concerns over food safety during the last years, there has been an intense attempt for eliminating or substituting antibiotic growth promoters in poultry feeds. Therefore, in order to investigate the impact of natural alternatives for antibiotics, an experiment was conducted to examine the comparative effect of nettle (Urtica dioica), probiotic (Primalac), prebiotic (Fermacto) and organic acid (Orgacid) on immune response of broilers. A total of 280 Ross 308 male broilers were randomly allotted to seven treatments, with four replicates per treatment (10 chickens per pen). Birds were offered either a maize-soybean meal basal diet (control, CON) or the basal diet supplemented with 10, 20 and 30 g/kg Urtica dioica (UD1, UD2 and UD3), 1 g/kg probiotic (Pro), 2 g/kg prebiotic (Pre) or 1 g/kg organic acid (OA). On day 35, the toe web swelling (cell-mediated response to phytohaemagglutinin-P) in the birds fed with UD3, Prp or OA diets was significantly higher (p<0.05) than the control birds. The spleen relative weight and secondary anti-SRBC titers in the birds fed with all dietary treatment, except for UD1 diet, were also significantly higher (p<0.05) than in birds fed the control diet, where the birds received UD3 and Pro diets had the highest secondary antibody titers. In conclusion, the results of present study suggest that feeding the higher levels of nettle, as well as other commercial feed additives (probiotic, prebiotic and organic acid), could improve immune response in broiler chickens.
