Effects of myo-inositol by different preparation methods on growth performance, physiology and intestinal inflammation related genes expressions in Cyprinus carpio var. jian

This study was conducted to investigate the effects of myo-inositol by different preparation methods on growth performance, plasma biochemical indicators, hepatic antioxidant capability and intestinal anti-inflammatory gene expressions of Cyprinus carpio var. jian. A basic diet (C, 34.64% of crude protein and 7.86% of crude fat) was formulated, and two experimental diets 400 mg/kg enzymatic myo-inositol (C+400E-MI) and chemical myo-inositol (C+400C-MI) in the basic diet were prepared. 180 healthy juvenile C. carpio var. jian (1.50±0.01) g were randomly distributed to 9 tanks in triplicate at the density of 20 fish per tank. After the 10-week feeding trial, the growth performance, liver antioxidant ability and intestinal inflammatory response-related gene expressions were determined. The results showed that the dietary E-MI and C-MI increased protein efficiency and protein deposition rate (P<0.05), and 400 mg/kg of dietary E-MI improved the weight gain rate and specific growth rate compared to the control group (P<0.05), and reduced the content of plasma lactate dehydrogenase (P<0.05). Compared to the basic group, 400 mg/kg E-MI supplementation significantly increased the activities of hepatic total superoxide dismutase (T-SOD), glutathione (GSH) and glutathione peroxidase (GPX) (P<0.05). 400 mg/kg C-MI supplementation significantly increased the hepatic GPX (P<0.05), while the content of malondialdehyde (MDA) increased as well (P<0.05). The intestinal gene expressions showed that the inclusion of E-MI and C-MI significantly down-regulated the mRNA expressions of pro-inflammatory factors in the fish intestine, e.g. IL-6, TNF-α and IL-12 (P<0.05). The inclusion of 400 mg/kg E-MI significantly reduced the mRNA expressions of anti-inflammatory factors, e.g. TGF-β1 and il-10 (P<0.05). In general, the supplementation of 400 mg/kg myo-inositol by different preparation methods improved the growth and feed utilization of juvenile C. carpio var. jian, and inhibited inflammatory response in the intestine. In addition, the enzymatic myo-inositol exhibited a better effect on growth improvement and antioxidant capacity enhancement of juvenile C. carpio var. jian. Therefore, enzymatic myo-inositol is a nutritional additive for aquatic animals that meets the requirements of green development.