Trial on using of some herbal extracts as promising immunoprophylaxis feed additives in cultured Oreochromis niloticus

Document Type : Original Article

Author

NRC, Vet. division, Hydrbiology Dept.

Abstract

Medicinal herbs and some plant extracts are natural feed additives which have a great impact on fish health. The present study focused on three dietary plant extracts to determine which one could be used as immunostimulant in aqua-feed. A total 210 apparently healthy O. niloticus with an avg. body weight 30 gram were stocked in 21 glass aquaria (10 fish\group\replicate) (3 replicate/group) and fed on pelleted diet supplemented with (0.5mg, 1mg onion leaves extracts{OE}, 0.5mg. 1mg barely seed extracts{BE}, 0.5mg, 1mg rice straw extracts {RE }and 0% additive) twice daily for two months. The blood picture, innate immunological parameters and response toward pathogens were assessed. At the end of experiment there was significant increase (P < 0.05) in serum lysozyme activity, phagocytosis in groups fed OE and BE extracts while there is no effect in fish fed RE extract. Globulin level and WBCS count increased in OE and BE groups. The result of this study demonstrated that fish groups fed on OEexhibited the highest immune performance and resistance against experimental infection with Aeromonas hydrophila, coming in the second rank the BE, and to lesser extent the RE which was nearly similar to control group. Therefore, we can recommend the use of onion leaves extract in aqua-feed at 0.5mg/kg diet and\or barley seed extract at 1mg/kg diet.

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