Short-Term Effect of a Low-Protein High-Carbohydrate Diet on Mature Female and Male, and Neomale Rainbow Trout

Abstract

Rainbow trout are considered as a poor user of dietary carbohydrates, displaying persistent postprandial hyperglycaemia when fed a diet containing high amounts of carbohydrates. While this phenotype is well-described in juveniles, less attention was given to broodstock. Our objective was to assess for the first time the short-term consequences of feeding mature female and male, and neomale trout with a low-protein high-carbohydrate diet on glucose and lipid metabolism. Fish were fed for two days with a diet containing either no or 32% of carbohydrates. We analysed plasma metabolites, mRNA levels and enzymatic activities of glycolysis, gluconeogenesis, de novo lipogenesis and β-oxidation in the liver. Results demonstrated that the glucose and lipid metabolism were regulated by the nutritional status in all sexes, irrespective of the carbohydrate intake. These data point out that carbohydrate intake during a short period (5 meals) at 8 °C did not induce specific metabolic changes in broodstock. Finally, we demonstrated, for the first time, sex differences regarding the consequences of two days of feeding on glucose and lipid metabolism.

Rainbow trout neomales broodstocks are able to eat and use a high carbohydrate diet during a complete reproductive cycle

“…While this feature is well-described in juveniles less attention is given to rainbow trout broodstocks and especially neomales that are used to produce all-female population. In a previous study we were able to demonstrate that a short carbohydrate intake (two-day feeding) did not induce specific metabolic changes in the liver of females, males and neomales broodstocks [13]. Moreover, we also demonstrated that neomales displayed more pronounced modifications of glucose and lipid metabolisms in response to nutritional status or HC diet compared to both females and males broodstocks.…”

“…Recently, we demonstrated that a short period of glucose intake (two day -5 meals) did not induce specific metabolic in mature female and male and neomale [13]. However, compared to both mature females and males, neomales displayed more pronounced modifications of their metabolism in response to nutritional status and HC diet (especially a huge increase in Gck mRNA levels) [13]. Although this could be attributed to their physiological status and weight close to juveniles during the experiment, it cannot be excluded that neomales are better user of high carbohydrate diet compared to juveniles.…”

“…However, as far as we know no studies focussed on their nutrition and potential effects of using specific formulated feed on their growth and reproductive performances. Recently, we demonstrated that a short period of glucose intake (two day – 5 meals) did not induce specific metabolic in mature female and male and neomale [13]. However, compared to both mature females and males, neomales displayed more pronounced modifications of their metabolism in response to nutritional status and HC diet (especially a huge increase in Gck mRNA levels)[13].…”

Vascular Endothelial Growth Factor A (VEGFA) Regulates Hepatic Lipid and Glycogen Metabolism in Schizothorax prenanti

“…In addition, fish have poor absorption capacity for dietary carbohydrates. They are susceptible to prolonged hyperglycemia, excessive hepatic lipid accumulation, growth retardation, and decreased immune function after long-term highcarbohydrate diet feeding [6][7][8]. Researchers used [U-14C] glucose as a tracer to prove that ingested glucose is synthesized into glycogen stored in fish livers [9].…”