Dietary sodium diacetate inclusion relieved hepatic glycogen deposition, oxidative stress, and intestinal microbial imbalance of largemouth bass (Micropterus salmoides) fed high dietary carbohydrate

Abstract

The present investigation was designed to identify whether sodium diacetate could improve the growth performance, antioxidant capacity, glucose metabolism and intestinal microbiome balance of largemouth bass (Micropterus salmoides) feeding high dietary carbohydrate. Three isonitrogen and isolipid diets comprising 0 g/kg, 1 g/kg, and 2 g/kg of sodium diacetate were manufactured. Each diet was fed to 105 juvenile largemouth bass of 5.8 g for nine weeks. The results demonstrated that dietary sodium diacetate significantly reduced the content of serum glucose and hepatic glycogen (P < 0.05). Meanwhile, dietary sodium diacetate incorporation significantly enhanced the expression of insulin receptor a (ira), insulin receptor b (irb), phosphoinositide-3-kinase regulatory subunit 1 (pi3kr1) and AKT serine/threonine kinase 1 (akt1) (P < 0.05), which were associated to the insulin pathway and partly correlated with the increased expression of genes related to glycolysis, such as glycerol kinase (gk) and phosphofructokinase liver type (pfkl). Moreover, the amount of malondialdehyde (MDA) was dramatically reduced with the addition of dietary sodium diacetate (P < 0.05). Additionally, the antioxidant capability was enhanced with the raise of nuclear factor erythroid derived 2 (nfr2) and the decrease of kelch like ECH associated protein 1 (keap1) being identified as a possible mediator (P < 0.05). The analysis of bacterial 16S rRNA V3–4 region indicated that the intestinal microbiota profile was significantly altered at both phylum and genus level with dietary sodium diacetate inclusion (P < 0.05), with decreased relative abundance of Mycoplasm, which belonged to Firmicutes. In conclusion, the addition of sodium diacetate to the ration improved glucose metabolism, antioxidant capacity and intestinal flora of largemouth bass and the optimal level of addition was 2 g/kg.