Effect of Scrophularia striata and Ferulago angulata, as alternatives to virginiamycin, on growth performance, intestinal microbial population, immune response, and blood constituents of broiler chickens.

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 feed-to-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 high-density 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.