A study on the influence of selected Indian herbal active principles on enhancing the immune system in Fenneropenaeus indicus against Vibrio harveyi infection

Five herbs such as Acalypha indica, Hygrophila spinosa, Picrorhiza kurooa, Tinospora cordifolia and Zingiber officinale were selected to screen for the in vitro immunostimulant activity against the shrimp pathogen Vibrio harveyi using different organic polar and non-polar solvents. After initial screening, the best extract of the five herbs was mixed thoroughly in equal proportion and made it an artificial immunostimulant diets (ISD) such as ISD-1(500), ISD-2 (1,000), ISD-3 (1,500) and ISD-4 (2,000) mg kg(-1). The control diet was prepared without adding immunostimulant herbal extracts. The Indian white shrimp, Fenneropenaeus indicus having the weight of 8.0 +/- A 1.0 g, were fed with the above diets for 60 days. After the completion of feeding trail, they were challenged with V. harveyi at the rate of 10(7)CFU/ml and found out the cumulative mortality, growth parameters, haematological and immunological parameters. The weight gain and specific growth rate were significantly (P < 0.05) increased from the control group to experimental group. The immunostimulant active principles helped to decrease the coagulation time and improved the total haemocyte count (THC), phagocytosis, phenol oxidase (PO) activity, haemagglutinin activity and bacterial clearance.