Effects of dietary starch levels on growth, feed utilization, glucose and lipid metabolism in non-transgenic and transgenic juvenile common carp (Cyprinus carpio L.)

Abstract

This experiment investigated the effects of dietary starch on growth performance, feed utilization, glucose and lipid metabolism of non-transgenic and growth hormone (GH) transgenic juvenile common carp (Cyprinus carpio L.). Transgenic common carp (TG fish) and non-transgenic (NT fish) were fed diets with five starch levels (0, 10%, 20%, 30%, 40%). After 41 days, TG fish showed higher growth and feed utilization at low-starch diets, while similar growth, lower feeding rate (FR) and slightly higher feed efficiency (FE) was observed at high-starch diets. Lower plasma glucose level and hepatic glycogen content were observed in TG fish, which could be related to the higher glycolysis (high gene expression of hexokinase (hk), p < 0.01) and gluconeogenesis (high gene expression of fructose-1,6-bisphosphatase (fbpase), p < 0.01; glucose-6-phosphatase (g6pase), p < 0.01) of TG fish. Compared to NT fish, weakened fat synthesis (lower gene expression of fatty-acid synthase (fas), p <0.01; acetyl-CoA carboxylase 1 (acc1), p < 0.01; acyl-CoA desaturase 1 (scd1), p = 0.011) and enhanced fatty acid oxidation (high gene expression of hormonesensitive lipase (hsl), p =0.01; carnitine palmitoyl transferase 1a (cpt-1a), p < 0.01), led to the decrease of body lipid content in TG fish. On the other hand, with increased dietary starch, increased body lipid and hepatic glycogen contents were observed in both TG and NT fish, suggesting that high dietary starch levels promoted glycolysis, fat synthesis and inhibited gluconeogenesis, fatty acid β-oxidation. Overall, TG fish showed higher growth performance at low starch diets, and higher ability of glycolysis, fatty acid oxidation and lower lipid synthesis than the NT fish.

Effects of native and pregelatinized starches on feed physical properties, digestibility, growth, nutrient utilization and histology of liver and intestine of juvenile tinfoil barb ( Barbonymus schwanenfeldii , Bleeker 1853)

“…Normal blood glucose level in fish ranges from 1.4 to 5.0 mmol/L and the post‐feeding concentration is set to be 16.7 mmol/L (Malik et al, 2020). The present study revealed a stable plasma glucose concentration after a 24‐hour feed deprivation might be due to a better control of glucose metabolism through glycolysis and lipogenesis (Guo et al, 2021) as revealed by uniform levels of serum cholesterol and triglyceride. A previous study in this species (16.2 g) fed with a commercial diet (>30% NFE) indicated 2 mmol/L blood glucose after 2 weeks of starvation (Eslamloo et al, 2017) might be due to difference in body size and long feed deprivation.…”

A novel ND1 mitochondrial DNA mutation is maternally inherited in growth hormone transgenesis in amago salmon (Oncorhynchus masou ishikawae)

“…For example, GH transgenic common carp ( Cyprinus carpio ) fed high dietary protein had better growth performance than non-transgenic common carp, lower glycolysis and lipid synthesis, and increased fatty acid oxidation 45 . In contrast, increasing dietary starch in this fish promoted glycolysis and lipid synthesis and suppressed glycogenesis and fatty acid β-oxidation 46 . Thus, it can be predicted that ROS production varies significantly due to the metabolic changes caused by diet.…”

Improved liver lipid catabolism and utilization in growth hormone transgenic common carp (Cyprinus carpio L.) through enhanced lipolytic and fatty acid β-oxidation pathways

“…It has also been reported that whole body lipid content of GH transgenic coho salmon increased with dietary energy level ( 30 ). Studies in GH transgenic common carp found that continuous expression of GH led to an increase in the expression level of lipolysis-related genes ( 31 ), a decrease in the expression level of hepatic lipid synthesis-related genes ( 32 , 33 ), and a decrease in whole body lipid content ( 10 ). Various changes in hepatic lipid metabolism caused by overexpressed GH in different fish species might suggest the complexity in mechanism of GH action.…”