Effects of low-protein-high-starch diet on growth performance, glucose and lipid metabolism of Amur sturgeon (Acipenser schrenckii) during feeding and starvation phases

Abstract

An 8-week growth (8 w) and 1-week starvation (S1 w) trial were conducted to investigate the effects of low-protein-high-starch diet on the growth performance, glucose and lipid metabolism in Amur sturgeon (initial body weight, 69.99 ± 0.06 g). Two diets with equal protein-to-energy ratios were fed, one diet contained 43.0% protein and 11.5% starch (HPLS) and the other contained 38.9% protein and 23.6% starch (LPHS). The results showed that LPHS diet did not compromise growth performance of Amur sturgeon, while the feeding rate increased significantly suggesting the keep of energy supplement. The LPHS diet also promoted the deposition of whole-body protein in Amur sturgeon after S1 w. An effective glucose metabolism response was observed that the transcript levels of glycolysis-related genes (gk) was upregulated significantly, suggesting that glucose catabolism was accelerated to maintain normal glycemic homeostasis and avoid hyperglycemia and glycogen accumulation during long-term feeding phase. Moreover, hepatic gluconeogenesis pathway (PEPCK, G6P) was upregulated to maintain normal plasma glucose levels of sturgeon in the LPHS group during S1 w phase. In addition, activated chrebp by high-starch intake induced excess glucose conversion to TG in the liver, which led to inhibit lipogenesis and accelerate lipolysis to prevent excessive fat accumulation after fed LPHS diet during feeding phase. Hepatic lipolysis (HSL) and β-oxidation (PPARα) were upregulated to satisfy energetic requirements, thereby promoting whole-body protein deposition. Our findings suggested that low-protein-high-starch diet could conserve dietary protein, and mitigate the excessive consumption of whole-body protein during starvation.