Use of α-Tocopherol in the formulated feeds of Indian major carp, Labeo rohita (Ham.), as a growth promoter and immunomodulator

Objective: This study was designed to examine the effect of three high levels of dietary intake of α-tocopherol acetate (Vitamin E) on growth and nonspecific immune response of Indian major carps (Labeo rohita L.). Particularly the data about the use of vitamin E in Indian major carps is scanty, so in this study, the effects of dietary vitamin E in common fish diets upon the Indian major carp (Labeo rohita Ham) non-specific immune system are studied, paying special attention to the dose of immunostimulant and the timing necessary to elicit an enhanced immune response. Method & Materials: Specimens were fed a formulated diet (without Vitamin E) as control, or Vitamin E supplemented diets (600, 1200 and 1800 mg α-tocopherol acetate kg-1) for 60 days feeding trial. Growth (NWG, ADG and SGR), serological parameters (such as TSP, TSA, TSG and A: G), different hematological parameters (such as TLC, TEC, Hct, MCV and MCH) and different non-specific immunological parameters (such as PR, PI, respiratory burst activity, leucocrit value and bactericidal activity) were evaluated during experimental trial. Results & Conclusion: Specimen fed the diet supplemented with 600mg vitamin E /kg showed no significant enhancement in immune parameters as compared to control feed fed fishes, while those fed with the diet supplemented with 1200 mg vitamin E /kg presented significant higher specific growth rate than control feed fed fishes. Similar trends were also observed in case of different haematological and serological parameters. In addition, different non-specific immune parameters such as PR, PI, NBT positive cells and bactericidal activity were highest in Exp-2 feed (1200 mg vitamin E kg-1) fed fishes. At the end of the experimental period, fishes of all the tanks were challenged with pathogenic bacteria Aeromonas hydrophila for 10 days [105 CFU/ml, 1 h and after 7 days 107 CFU/ml, 1 h]. Highest survival percentage (96.65%) was observed in the diet Exp-2 fed fishes where as 30 % in control, which indicates the effectiveness of Vitamin E in survivability. The highest Vitamin E dietary dose used, 1800 mg /kg, unexpectedly provoked no immunostimulation. These results indicate that a moderate level of Vitamin E in the diet (1200 mg vitamin E /kg) stimulates the Indian major carps non specific immune system.