Dietary manganese requirement of juvenile large yellow croaker Larimichthys crocea (Richardson, 1846)

Abstract

A 9-week feeding trial was conducted to determine the dietary manganese (Mn) requirement of juvenile large yellow croaker Larimichthys crocea (Richardson, 1846) (initial mean weight 7.71±0.02g). Manganese sulfate monohydrate (MnSO4·H2O) was added to the semi-purified basal diet to prepare 6 experimental diets with graded levels of Mn (2.33, 7.63, 13.16, 18.27, 24.05 and 41.79mg/kg, respectively). Results showed that the specific growth rate (SGR), feed efficiency (FE), Mn concentrations in whole-body, liver and vertebra, and activities of hepatic Mn superoxide dismutase (Mn-SOD) and total SOD (T-SOD) were significantly improved by dietary Mn supplementation (P<0.05). However, fish fed the basal diet with 2.33mg/kg of Mn had the significantly highest Mn retention, proportion of hepatic Mn to whole-body Mn and activity of copper–zinc superoxide dismutase (Cu–Zn SOD) (P<0.05). As biomarkers of oxidative stress, malondialdehyde (MDA) and protein carbonyl (PC) in serum were significantly higher in fish fed the basal diet (P<0.05). Using the broken-line models based on SGR and hepatic Mn-SOD activity, dietary Mn requirements of the juvenile large yellow croaker were estimated to be 16.44 and 16.16mg/kg, respectively. Statement of relevanceThis study is not a test of commercial aquaculture.