The interactive effect of dietary inclusion levels and preparation methods of myo-inositol on growth performance, antioxidant function and lipid metabolism homeostasis of Cyprinus carpio var. jian

To evaluate the interactive effect of inclusion levels (IL) and preparation methods (PM) of myo-inositol (MI) on growth performance, hepatic antioxidant capacity and lipid metabolism of Cyprinus carpio var. jian, five isonitrogenous and isoenergetic diets were formulated at a high level of dietary fat content (11.3%, HF basic diet), supplemented with 400 mg/kg or 800 mg/kg of enzyme biocatalysis MI (E-MI) (400E-MI, 800E-MI) and chemical acid hydrolysis MI (C-MI) (400 C-MI, 800 C-MI). 300 healthy C. Carpio var. jian (1.5 ± 0.1 g) were randomly fed one of the five experimental diets in triplicates (20 fish per tank) for 66 days. After the 66 days feeding trial, the growth performance, plasma biochemistry, hepatic antioxidant enzyme activities, and gene expressions related to lipid metabolism were determined. Two-way ANOVA analysis showed that PM and IL of dietary MI had an interactive effect on growth performance, antioxidant capacity and lipid metabolism of C. Carpio var. jian. The IL significantly affected protein deposition rate (PDR), activities of hepatic CAT, T-SOD and GPx (P < 0.05). Specifically, final average weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and PDR in the 400E-MI group and 800 C-MI group were significantly higher than those in the 400 C-MI group (P < 0.05). The oil red O staining results showed that a large amount of lipid accumulation in the liver tissues of the HF group, while the hepatic lipid accumulations of 400 C-MI, 400E-MI and 800 E-MI were significantly reduced (P < 0.05). The expressions of lipid metabolization-related genes showed that the myo-inositol PM and IL had an interactive effect on mRNA expressions of hepatic ACO, ACSL, PPARβ and SIRT1 (P < 0.05). The mRNA expression levels of ACC, AMPK, PPARβ and SREBP-1 were significantly affected by IL (P < 0.05). Specifically, The mRNA expressions of LPL, PPARβ and SIRT1 of 400 C-MI, 400E-MI and 800 E-MI groups were significantly higher than those of the HF basic group. Overall, the supplementation of C-MI and E-MI in the HF diet improved the protein deposition and liver antioxidant ability, promoted lipid metabolism through activating AMPK and SIRT1 of C. Carpio var. jian fed HF diet.