Effect of dietary iron levels on growth, iron concentration in tissues, and blood concentration levels of transferrin and hepcidin in bighead carp (Aristichthys nobilis)

A 60‐day feeding trial was conducted to estimate the effects of dietary iron (Fe) levels on growth, Fe concentration in the liver, spleen, and blood, and transferrin and hepcidin concentrations in the blood of bighead carp (Aristichthys nobilis). The six experimental diets were formulated to contain different Fe levels (0, 43.1, 84.2, 123.3, 162.2 and 203.1 mg/kg of dry diet) using ferrous sulphate (FeSO₄) as the source. The weight gain (WG) and the specific growth ratio (SGR) of A. nobilis fed with a dietary Fe level of 123.3 mg/kg were significantly higher than that of the 0 mg/kg Fe group (p   liver > whole body. When the Fe dietary content increases to 162.2 mg/kg, the blood concentrations of Fe significantly decreased and thereafter increased, hepcidin significantly decreased and thereafter decreased, and transferrin significantly increased and thereafter decreased. The results indicate that the transferrin blood content significantly increased with decreasing hepcidin of up to 264.63 μg/ml content and thereafter decreased. It could be concluded that after transferrin saturation, hepcidin functions to maintain iron balance in the blood of A. nobilis by decreasing transferrin content.