The objective of the study was to compare the effects of antibiotic virginiamycin, probiotic Protexin® and Plantago major L. (plantain) on performance, serum metabolites, immune response, and the ileal microbial population of broilers. The experiment was carried out with a total of 200 day-old male Ross 308 broiler chickens in a completely randomized design. Chickens were allocated to five groups consisting of T1: control diet (Con), T2: Con+0.02% virginiamycin, T3: Con+0.01%
Protexin, T4: Con+0.5% plantain and T5: Con+1% plantain. Each group was divided into four replicates consisting of ten chicks each. In comparison with the control group, body weight gain increased in chickens fed Protexin and 0.5% plantain groups in the starter period, as well as by antibiotic in grower and finisher periods and by 1% plantain in all periods (P < 0.01). Supplementation of plantain and virginiamycin increased (P < 0.01) feed intake in the starter and finisher periods, respectively. Feed conversion ratio improved (P <0.05) in finisher period only by virginiamycin. All treated birds showed an elevated relative weight of carcass and bursa, and plantain increased relative weight of the spleen (P < 0.01). All treatments demonstrated a hypocholesterolemic effect (P < 0.01) and higher level of plantain (1%) decreased (P < 0.05) serum glucose, triglyceride and low-density lipoprotein-cholesterol as well. The inclusion of Protexin and plantain enhanced immune system with increased white and red blood cells as well as second anti-SRBC immune response and reduced heterophil/lymphocyte ratio in SRBC injected birds (P <0.05). Virginiamycin decreased ileal microbial population of
Lactobacillus while Protexin and plantain increased it (P < 0.01). Meanwhile, 1% plantain suppressed ileal E. coli counts. In conclusion,1% Plantago major L. performed the best in this study because it led to increased body and carcass weight, lowered serum cholesterol and triglyceride, reduced heterophil/lymphocytrat