BACKGROUND: Outbreak and spread of bacterial infections resulted in increasing use of antibiotics which subsequently leaded to bacterial resistance to conventional antibiotics. Objectives: To evaluate the effects of organic acids (Selko-pH®), Probiotic (PrimaLac®) and Echinacea purpurea (EP) alcoholic extract on the immune system of the broiler chickens, a completely randomized design experiment was conducted over 120 one-day-old male broiler chicks (Ross 308) with 4 treatment groups that each treatment consisted of 3 replications with 10 birds in each pen. Methods: Groups were designed as follow: group one received organic acid constantly in drinking water (1:1000 v/v) until 14th day and then received 8 hours in a day consecutively (OA); group two received Probiotic (PrimaLac®) water soluble (by 14th day) and mix in the feed (until the end of the rearing period) (PM); group three received EP alcoholic extract in drinking water (1:1000 v/v) like organic acid group and group four were considered as control (received no feed additives). Results: All groups except the control increased the relative weight of the spleen and Bursa of Fabricius as lymphoid tissues; however, this increase was statistically significant only in the case of EP group (p≤0.001). Data of antibodies test against sheep red blood cells and heterophil to lymphocyte ratio also showed that all groups except the treatment of organic acid had significant differences in terms of specific and cellular immune responses (p<0.01). The data of total count of bacteria and also Lactobacilli bacteria in cecal’s content obviously showed that the number of Lactobacilli bacteria significantly increased in PM and OA treatments (p≤0.05). ConclusionS: Feed additives used in these experiments have the ability to improve the immune system.

BACKGROUND: Herbal immunostimulants have numerous potential benefits in comparison to vaccines and drugs like antibiotics in aquaculture. OBJECTIVES: In this study, effects of administration of Echinacea purpurea in oral and intra peritoneal routs on some hematological and immunological parameters of the grass carp (Ctenopharyngodon idella) were investigated. METHODS: A total of 240 healthy juvenile grass carp were randomly divided into four equal groups in triplicates. Group 1 received 400 mg/kg b.w. Echinacea in intra peritoneal injection. Group 2  received 0.5% Echinacea in their daily food. Group 3 and 4 were considered as injection control and oral control, respectively. Fish were bled on day 0, 10, 20, 30 and 40 of study. Sera samples were assayed for immunological parameters: lysozyme activity, serum bactericidal activity, complement activity and NBT reduction assay. Blood samples were also used for hematological parameters: (PCV, Hb, RBC, WBC and Leukocyte differentiated count). RESULTS: Results showed that serum lysozyme and bactericidal activity as well as complement and NBT reduction activity were significantly higher in i.p. treatment than the control group (p<0.05), while in oral treatment bactericidal and NBT reduction activity increased significantly on days 30 and 40 (p<0.05). Hematological assay shows no significant differences in PCV, Hb and RBC values at each sampling period in oral and injection compared to controls (p>0.05) but WBC count and  rate of heterophils showed an increase in injection treatment group compared with the control (p<0.05). Mortality rate after challenged with A. hydrophila decreased in Echinacea treated treatments. CONCLUSIONS: This study indicates that administration of E. purperea stimulates some nonspecific immune responses in grass carp and therefore it can be recommended as an herbal immunostimulant in fish.