An experiment was conducted to investigate the comparative effect of Scrophularia striata, Ferulago angulata, and virginiamycin (VM) on performance, intestinal microbial population, immune response, and blood constituents of broilers. A total of 300 Ross 308 male broiler chickens were randomly assigned to 5 treatments, with 5 replicates/treatment (10 chickens/pen). Birds were fed either a corn–soybean meal basal diet (control) or the basal diet supplemented with 200 mg/kg VM; 4 g/kg S. striata (SS1); 8 g/kg S. striata (SS2); 4 g/kg F. angulata (FA1); or 8 g/kg F. angulata (FA2). After 6 wk, the BW, ADG, and feedto- gain ratio (F:G) of the VM, SS1, and FA1 groups were better (P < 0.01) compared with the control group. At 42 d, cecal lactobacillus counts were higher (P = 0.032) in SS2 and FA2 groups compared with the control and VM groups. In addition, broilers fed any of the diets exhibited lower coliform counts (P < 0.05) in the ileum and ceca than those fed the control diet. Total and IgG antibody titers against SRBC for secondary responses, relative spleen weight, and lymphocyte counts were higher (P < 0.05) in birds fed the SS2 or FA2 diet compared with the control group. Moreover, feeding the SS2 or FA2 diet decreased (P < 0.05) the blood heterophil/lymphocyte ratio and plasma triglyceride level, whereas only the SS2 diet increased (P = 0.037) the white blood cell counts compared with the control diet. All diets, except for the VM diet, decreased (P = 0.009) the plasma cholesterol level compared to the control treatment. The plasma highdensity lipoprotein cholesterol level was also increased (P = 0.042) in the SS2 and FA2 groups. In conclusion, dietary S. striata or F. angulata at a level of 4 g/kg diet enhanced growth performance, which was comparable to that of VM used as an antibiotic growth promoter. Furthermore, a high dose of both herbs (8 g/kg diet) could beneficially affect the intestinal health and immune status of broilers.
