Effect of Indian lotus (<i>Nelumbo nucifera</i>Gaertn.) leaf powder on immune status and disease resistance of Nile tilapia

Abstract

This study assessed the immune response of Nile tilapia (Oreochromis niloticus L.) after feeding on different levels (0.1%, 0.2% and 0.4%) of dietary Indian lotus (Nelumbo nucifera) leaf powder for 45 days. We evaluated both the nonspecific immune response at the end of the feeding period and the resistance to Aeromonas hydrophila. Exposure to Indian lotus resulted in a significant elevation in serum total globulins, serum lysozyme activity, serum killing percentage and the phagocytic activity (p < 0.05). Total serum protein and albumin showed no remarkable variation between tilapia fed on 0.1% Indian lotus and the control group (p > 0.05). In addition, the relative expressions of immune-related genes, namely interleukin–1β and tumour necrosis factor–α were significantly up-regulated in tilapia fed on 0.4% Indian lotus as compared to the control group; their expressions were down-regulated in the other tested groups (p < 0.05). The survival rate of Nile tilapia postchallenge to A. hydrophila reported a significant and dose-dependent increase in the Indian lotus-supplemented groups (p < 0.05). Therefore, dietary incorporation of Indian lotus leaves (0.4%, 0.2% and 0.1%) could strengthen the immunity of Nile tilapia and improve its resistance to A. hydrophila infection. Therefore, Indian lotus leaves could serve as potential feed supplements for Nile tilapia.