Iron (Fe) is an essential element; however, higher dose can cause lipid peroxidation in key tissues that could exert toxic effects in fish. Iron toxicity can be mitigated by using functional feed additives such as vitamin-C (VC) and bentonite (BT) . Vitamin C is a reducing agent that helps in facilitating iron uptake in gut, and bentonite acts as a chelating agent to remove iron from the body. Bentonite scavenges and binds free iron to prevent reactive oxygen species (ROS) from being produced to prevent peroxidation. Our study investigated the effect of dietary supplementation of BT and VC in mitigating the fee d-borne iron toxicity in rainbow trout. Two experiments were conducted to achieve the goal.
Experiment 1: Bentonite study: Six diets 0% BT (Con), 2 and 4% BT (HB), 0.25% iron as FeSO4 ( Fe), Fe+2% BT (LBFe ), and Fe+4% BT (HBFe) were fed to trout for 8 weeks . Iron exhibited negative impacts on growth and increased the iron load in liver (Figure A), whereas BT supplementation improved the growth and reduce the iron load in liver. O xidative status was enhanced in BT+Fe fed groups compared to the Fe group. Liver showed infiltration with inflammatory cells and necrosis in Fe and HB groups whereas LBFe group appears to be normal.
Figure: Iron load in liver (A), Hepcidin (HAMP) gene expression in liver (B)
Experiment 2: BT and VC Study : Fish fed seven diets:
Overall dietary supplementation of vitamin C and bentonite can be an effective approach to mitigate the iron toxicity in trout aquaculture industry.