Dietary hydroxymethionine-chelated manganese improved growth and Mn deposition, regulated lipid metabolism and enhanced antioxidant capacity by reducing endoplasmic reticulum stress and autophagy for juvenile Litopenaeus vannamei

Abstract

The study investigated the effects of dietary manganese (Mn) supplementation on growth, Mn deposition, antioxidant capacity and lipid metabolism of Litopenaeus vannamei. Six diets were formulated to contain 16.29, 23.49, 30.69, 37.89, 45.09 and 73.89 mg/kg Mn (hydroxymethionine-chelated Mn was used as a Mn source). Results showed that shrimp fed 30.69–45.09 mg/kg Mn exhibited better growth performance. Mn deposition in muscle, hepatopancreas and carapace was positively correlated with dietary Mn levels. Shrimp fed 30.69 mg/kg Mn exhibited the highest total-antioxidant capacity and triglyceride in serum among all treatments. Dietary 16.29 and 23.49 mg/kg Mn significantly increased the antioxidant and immune capacity in serum compared to the other diets. The highest activities of alkaline phosphatase, acid phosphatase, and nitric oxide synthase in the hepatopancreas were found at shrimp fed diet with 30.69 mg/kg Mn. Shrimp fed 16.29 mg/kg Mn showed the highest concentration of malondialdehyde in serum and hepatopancreas. Shrimp fed 16.29 and 73.89 mg/kg Mn showed the lowest lipid drop area in hepatopancreas. The expression levels related to Mn absorption and transport were significantly up-regulated with increase of dietary Mn levels, while dietary 16.29–30.69 mg/kg Mn down-regulated the transcription levels related to endoplasmic reticulum stress and apoptosis. 30.69 mg/kg Mn significantly up-regulated the expression levels related to lipid synthesis, and down-regulated the expression levels related to lipid catabolism. Together, the recommended Mn requirement was 30.90 mg/kg for L. vannamei based on two slope broken-line analyses. Dietary Mn improved growth and antioxidant capacity by reducing endoplasmic reticulum stress and autophagy.