Effect of supplementary manganese on growth performance, tissue manganese content, antioxidant activities, and cytosolic manganese superoxide dismutase gene mRNA expression in juvenile Chinese mitten crabs (Eriocheir sinensis)

Abstract

A 50-day feeding trial was conducted to determine the dietary manganese (Mn) requirement of juvenile Chinese mitten crabs Eriocheir sinensis. Manganese sulfate monohydrate (MnSO4·H2O) was added to a semi-purified basal diet to prepare six experimental diets with graded levels of Mn (0, 10, 20, 40, 80, and 160 mg/kg) providing the actual dietary Mn value of 2.12, 12.26, 22.45, 33.78, 44.05, and 66.18 mg/kg. Results showed that Mn supplementation significantly (P 0.05). Mn concentration in the whole body and hepatopancreas significantly increased with increasing levels of dietary Mn supplementation. However, crabs fed an additional 2.12 mg/kg of Mn had a significantly (P < 0.05) higher Mn retention and proportion of hepatic Mn to whole-body Mn than other groups. As biomarkers of oxidative stress, malondialdehyde content in the serum was significantly higher in crabs fed the basal diet (P < 0.05). The mRNA expression of the cytosolic Mn-SOD gene in the hepatopancreas was upregulated with increasing dietary Mn levels up to 22.45 mg/kg and then plateaued. Using the broken-line model based on WGR, the dietary Mn requirement of the juvenile Chinese mitten crab was estimated to be 30.34 mg/kg.