Effects Of Dietary Carbohydrate Levels Research Articles

Effects of dietary carbohydrate levels on growth performance, feed utilization, liver histology and intestinal microflora of juvenile tiger puffer, Takifugu rubripes

An 8-week feeding trial was conducted to investigate the effects of dietary carbohydrate levels on growth performance, body composition, and plasma biochemical parameters, liver and gut histology, and intestinal microbiota of Takifugu rubripes. Five isonitrogenous and isolipidic experimental diets were formulated with graded levels of cassava starch: 0% (C0), 8% (C8), 16% (C16), 24% (C24), and 32% (C32). The results showed that weight gain rate, specific growth rate (SGR) and protein efficiency ratio significantly increased in C16 and C24 groups (P < 0.05), while the feed conversion ratio expressed an opposite trend. Feeding rate is decreased with the increasing of carbohydrate levels (P < 0.05). Liver lipid content was dramatically increased in C24 treatment (P < 0.05). The intestinal amylase activity and muscle glycogen content were higher than other groups (P < 0.05). Plasma glucose levels were increased in C24 and C32 groups (P < 0.05). In addition, the abundance of intestinal potentially pathogenic bacteria (Staphylococcus) decreased, and the intestinal probiotics (Lactobacillus) increased with the increasing of dietary carbohydrate level (P < 0.05). The intestinal bacteria, indicated by Sobs, Chao and Shannon indexes, were more diverse with the increasing of the carbohydrate level (P < 0.05), meanwhile the abundance of transport and metabolism of carbohydrate, lipid and amino acid were enhanced with the increasing of carbohydrate levels (P < 0.05). In conclusion, appropriate supplementation of carbohydrate in diet promoted growth performance and feed utilization of juvenile Takifugu rubripes, and increased the liver lipid and muscle glycogen content, as well as intestinal microbial diversity. Based on the quadratic regression between SGR and carbohydrate levels, the optimal dietary carbohydrate level of juvenile Takifugu rubripes is 21.6%.

Combined effects of dietary carbohydrate levels and ammonia stress on growth, antioxidant capacity and glucose metabolism in juvenile oriental river prawn (Macrobrachium nipponense).

Ammonia is a common environmental stress factor that constrains aquaculture industry development. This study evaluated the effect of carbohydrate levels and ammonia stress in oriental river prawn (Macrobrachium nipponense). The experiment had six treatments containing two water ammonia levels (0 and 5 mg/L) and three dietary carbohydrate levels (low carbohydrate diet (LCD, 10%), medium carbohydrate diet [MCD, 20%], and high carbohydrate diet [HCD, 30%]), and lasted six weeks. The results showed that the prawns fed on MCD had higher weight gain than those fed on LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower acid phosphatase and alkaline phosphatase activities during ammonia stress. Feeding the prawns on the MCD increased B cells in the hepatopancreas during ammonia stress. Interestingly, the prawns fed on MCD had significantly lower superoxide dismutase activity compared to LCD and HCD during ammonia stress. Moreover, the prawns fed on MCD had significantly lower pyruvate kinase activity and pyruvate and lactic acid contents, while those fed on LCD had significantly higher succinic dehydrogenase, 6-phosphogluconic dehydrogenase, and phosphoenol pyruvate carboxykinase activities during ammonia stress. The prawns fed on the MCD increased significantly glutaminase activity and decreased the ammonia content in the serum during ammonia exposure. In addition, feeding the prawns on MCD decreased significantly the expression of apoptosis and inflammation-related genes. Taken together, the MCD supplied energy required to counteract ammonia stress, which increased growth, improved antioxidant capacity, facilitated ammonia excretion, and alleviated inflammation and apoptosis of the oriental river prawn.

Post-nursing early life macronutrient balance promotes persistent and malleable biometric and metabolic traits in mice.

It is known that dietary factors within the gestational and nursing period affect early life and stably affect later life traits in animals. However, there is very little understanding of whether dietary factors within the early life period from post-nursing to adulthood affect traits in adulthood. To address this, we conducted studies on male C57Bl/6J mice fed from 3weeks (immediately post-nursing) until 12weeks (full maturity) using nine different diets varying in all three major macronutrients to parse out the effects of individual macronutrients. Early life macronutrient balance affected body composition and glucose homeostasis in early adulthood, with dietary protein and fat showing major effects. Despite this, mice showed rapid reversal of the effects on body composition and glucose homeostasis of early life diet feeding, upon standard diet feeding in adulthood. However, some traits were persistent, with early life low dietary protein levels stably affecting lean and muscle mass, and early life dietary fat levels stably affecting serum and liver triglyceride levels. In summary, macronutrient balance in the post-nursing early life period does not stably affect adiposity or glucose homeostasis but does impact muscle mass and lipid homeostasis in adulthood, with prominent effects of both protein and fat levels. KEY POINTS: Early life dietary low protein and high fat levels lowered and heightened body mass, respectively. These effects did not substantially persist into adulthood with rapid catch-up growth on a normal diet. Early life protein (negative) and fat (positive) levels affected fat mass. Early life low protein levels negatively affected lean mass. Low protein effects on lower lean and muscle mass persisted into adulthood. Early life macronutrient balance effects did not affect later life glucose homeostasis but early life high fat level affected later life dyslipidaemia. Effects of dietary carbohydrate levels in early and later life were minor.

Effects of short-term carbohydrate deprivation on glycolipid metabolism and hepatic lipid accumulation in mice.

To investigate the effect of dietary carbohydrate levels on liver glycolipid metabolism, this study used C57BL/6J male mice receiving standard diet (CON), no-carbohydrate high-fat diet (NCD), and high-carbohydrate no-fat diet (HCD). One week after intervention, mice in the NCD group showed lower blood glucose, HbA1c and LDL-C as well as liver weight and liver index compared with the CON group. Further research found that the liver fat synthesis genes of mice in the NCD group were significantly down-regulated at the gene level, and histopathological sections showed that the livers of mice in the NCD group had less lipid accumulation. Furthermore, liver metabolomic analysis showed that primary bile acid levels and acylcarnitine levels in the liver of mice in the NCD group were significantly increased, and conversely, lysophosphatidylcholine and fatty acyl metabolites were significantly decreased. KEGG metabolic pathway analysis showed that metabolic pathways such as biosynthesis of unsaturated fatty acids and starch and sucrose metabolism were significantly inhibited in mice in the NCD group, while metabolic pathways such as primary bile acid biosynthesis, linoleic acid metabolism and glycerophospholipid metabolism were enhanced. Taken together, these results indicate that short-term carbohydrate deprivation improves blood glucose and lipid metabolism levels in mice; the molecular mechanism of action may involve inhibition of de novo lipogenesis and enhancement of bile acid metabolism.

Effects of dietary carbohydrate levels on growth, metabolic enzyme activities and oxidative status of hybrid snakehead (Channa maculata ♀ × Channa argus ♂)

An 8-week feeding trial was aimed to explore the effects of dietary carbohydrate on growth performance, metabolic enzyme activities and oxidative status of hybrid snakehead (Channa maculata ♀ × Channa argus ♂). A total of 540 healthy hybrid snakehead with initial body weight of (39.4 ± 0.01) g were selected and randomly divided into 18 cages, with 30 in each cage. Six isonitrogenous and isolipidic diets with different levels of digestible carbohydrate (α-starch) levels (DCL) (0%, 5%, 10%, 15%, 20% and 25%) were fed to hybrid snakehead. Results showed that dietary carbohydrate supplementation had significant effects on final body weight (FW), weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) of hybrid snakehead in a third order polynomial (cubic) model, with the optimal level established at 10.2%–12.0%. Effects on Condition factor (CF) of hybrid snakehead was described by a second order polynomial (quadratic) relationship. Hepatosomatic index (HSI) and viscerosomatic index (VSI) showed a linear relationship with increasing DCL. The body protein, crude lipid and hepatic glycogen content of hybrid snakehead increased with the levels of carbohydrate supplementation (P < 0.05). Dietary supplementation with carbohydrate significantly increased the levels of plasma cholesterol (CHOL), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in hybrid snakehead (P < 0.05). The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in both plasma and liver were significantly enhanced by the highest level of carbohydrate (P < 0.05). Furthermore, the levels of superoxide dismutase (SOD) and catalase (CAT) in liver increased firstly and then decreased with the increasing of DCL (P < 0.05). The expression levels of genes encoding SOD, glutathione peroxidase (GSH-PX), proinflammatory cytokines interleukin 1β (IL-1β) and interleukin 8 (IL-8) in liver showed significantly increasing trend when DCL increased from 0% to 15%, followed by significant decline when DCL exceeds 15% (P < 0.05). The malondialdehyde (MDA) contents in liver were not affected by DCL. Based on these results, the optimal level of dietary carbohydrate supplementation was estimated at approximately 11% for maximum growth and normal metabolism of hybrid snakehead.

Effects of dietary carbohydrate on growth, feed utilization, hepatic glucose and lipid metabolism in endangered Yangtze sturgeon (Acipenser dabryanus)

The aim of this study was to determine the effects of dietary carbohydrate levels on growth performance, feed utilization and metabolism of juvenile Yangtze sturgeon (Acipenser dabryanus). Six isonitrogenous (crude protein 45 %) and isolipidic (crude lipid 10 %) experimental diets were formulated containing 7.35 %, 10.2 %, 13.4 %, 16.5 %, 19.4 % and 22.4 % carbohydrate. Triplicate groups of 15 fish (initial weight, 51.4 ± 0.16 g) were fed twice daily for 8 weeks. The significantly higher (P < 0.05) growth performance was recorded in dietary 19.4 % group compared with the dietary 7.35 % and 10.2 % groups. Meanwhile, higher dietary carbohydrate (16.5 %, 19.4 % and 22.4 %) also significantly improved feed conversion ratio compared with the lowest one (7.35 %). Protein efficiency ratio exhibited similar tendency with growth performance. And the highest muscle crude protein was found in 19.4 % group and was significantly higher than the lower dietary carbohydrate groups (7.35 %, 10.2 %, 13.4 %) (P < 0.05). Liver glycogen content was positively correlated with dietary carbohydrate levels. The highest dietary carbohydrate level (22.4 %) led to much more lipid deposition in the body. Furthermore, the highest mRNA expression of Acetyl-CoA carboxylase and fatty acid synthesis were also recorded in dietary carbohydrate 22.4 % group. mRNA expression of glycolysis related genes hexokinase was significantly (P < 0.05) up-regulated by higher levels of carbohydrate (19.4 % and 22.4 %) compared with other treatments. Quadratic broken-line analysis of weight gain against carbohydrate levels showed that the optimal value was 20.6 % of diet for Yangtze sturgeon.

Effects of Dietary Carbohydrate Levels on Growth Performance, Body Composition, Antioxidant Capacity, Immunity, and Liver Morphology in Oncorhynchus mykiss under Cage Culture with Flowing Freshwater.

The purpose of this study is to investigate the effects of dietary carbohydrate levels on growth performance, body composition, antioxidant capacity, immunity, and liver morphology in Oncorhynchus mykiss under cage culture with flowing freshwater. Fish (initial body weight 25.70 ± 0.24 g) were fed five isonitrogenous (420 g/kg protein) and isolipidic (150 g/kg lipid) diets containing 50.6, 102.1, 151.3, 200.9 and 251.8 g/kg carbohydrate levels, respectively. The results indicated that fish fed diets containing 50.6-200.9 g/kg carbohydrate showed significantly higher growth performance, feed utilization, and feed intake than those fed 251.8 g/kg dietary carbohydrate levels. Based on the analysis of the quadratic regression equation for weight gain rate, the appropriate dietary carbohydrate requirement of O. mykiss was estimated to be 126.2 g/kg. 251.8 g/kg carbohydrate level activated Nrf2-ARE signaling pathway, suppressed superoxide dismutase activity and total antioxidant capacity, and increased MDA content in the liver. Besides, fish fed a diet containing 251.8 g/kg carbohydrate showed a certain degree of hepatic sinus congestion and dilatation in the liver. Dietary 251.8 g/kg carbohydrate upregulated the mRNA transcription level of proinflammatory cytokines and downregulated the mRNA transcription level of lysozyme and complement 3. Whole-body compositions were not affected by dietary carbohydrate levels. In conclusion, 251.8 g/kg carbohydrate level suppressed the growth performance, antioxidant capacity and innate immunity, resulting in liver injury and inflammatory response of O. mykiss. A diet containing more than 200.9 g/kg carbohydrate is not efficiently utilized by O. mykiss under cage culture with flowing freshwater.

Effect of dietary carbohydrate level on growth, feed utilization, energy retention, body composition, and digestive and metabolic enzyme activities of juvenile cobia, Rachycentron canadum

Carnivorous fish, such as cobia Rachycentron canadum, tend not to have a specific requirement for dietary carbohydrates (CBH). However, if CBH is not provided in the diet, other energy-yielding nutrients, such as protein and lipids, are catabolized to produce energy. Therefore, knowing the optimum level of dietary CBH would be useful for cobia aquaculture. In the present study, four isonitrogenous and isolipidic diets were prepared to investigate the effects of dietary CBH level (4.8–22.5 %) on growth performance and body composition of, and feed utilization, by juvenile cobia (initially weighing 22.2 ± 0.27 g/fish). Each diet was given to triplicate groups of cobia for 8 weeks. Both the final body weight and specific growth rate increased with increasing dietary CBH levels. Feed intake decreased with increasing dietary CBH levels (P < 0.05), whereas, feed efficiency and the protein efficiency ratio increased (P < 0.05). As the level of dietary CBH increased, the condition factor, hepatosomatic index, viscerosomatic index, and intraperitoneal fat ratio generally increased (P < 0.05). The whole-body lipid content generally increased with increasing dietary CBH levels, with the lipid content of fish fed a 22.5 % dietary CBH diet being significantly higher than other treatments. Moisture content showed the reverse response to that of lipids. Body protein and ash contents were not significantly related to dietary CBH (P > 0.05). Activities of hepatic glucokinase increased with increasing dietary CBH levels, being significantly higher in fish fed a 22.5 % CBH diet compared with other groups (P < 0.05). In contrast, the activities of hepatic hexokinase and pyruvate kinase showed the opposite trend. The activities of intestinal amylase and trypsin were negatively related to dietary CBH levels. Thus, dietary CBH promoted the growth and feed utilization of cobia, although it also had negative effects, such as higher lipid deposition and higher body indices. Based on these results, we recommend that inclusion of CBH in the diet of cobia is beneficial, whereas, the optimal level of CBH should be carefully evaluated.

Effects of dietary carbohydrate levels on growth performance, body composition, glucose/lipid metabolism and insulin signaling pathway in abalone Haliotis discus hannai

The present study investigated the effects of different dietary carbohydrate levels on the growth performance, body composition, glucose/lipid metabolism and insulin signaling pathway in abalone Haliotis discus hannai. Eight experimental diets with graded levels of carbohydrates (18.08%, 22.10%, 26.10%, 29.90%, 34.00%, 38.01%, 41.98% and 45.55%, named as T1, T2, T3, T4, T5, T6, T7 and T8, respectively) were designed to feed abalone (initial weight 22.52 ± 0.05 g) for 110 days. The results showed that the diet containing 38.01% carbohydrate significantly increased the survival rate (SR) and weight gain rate (WGR) of abalone (P < 0.05). Based on the quadratic regression mode of WGR, the optimal dietary carbohydrate level for abalone was estimated to be 37.05%. The activities of intestinal digestive enzymes were significantly increased in the T6 group. Moreover, the expressions of pyruvate kinase (pk) and glucose-6-phosphate dehydrogenase (g6pdh) in digestive glands were up-regulated with the increase of carbohydrate content in diets, while the expression of hexokinase (hk) reached the maximum in the T6 group. The highest expressions of phosphoenolpyruvate carboxykinase (pepck), glucose-6-phosphatase (g6pase) and insulin signaling pathway related genes were found in the T6 group. The expressions of key genes related to lipolysis reached the highest in the T6 group, and then down-regulated with the further increasing dietary carbohydrate levels. The expression of key genes of lipogenesis was up-regulated with the increasing dietary carbohydrate levels. In conclusion, 38.01% of dietary carbohydrate level improved the growth performance of abalone. Dietary carbohydrate levels influenced the glucose and lipid metabolism including insulin signaling pathway. Abalone potentially had the capability to deal with a high-carbohydrate load (45.55%) by increasing glycolysis and decreasing gluconeogenesis. Meanwhile, it promoted lipid synthesis and inhibited lipolysis under high dietary carbohydrate load.

Effects of Dietary Carbohydrate Levels on the Growth and Glucose Metabolism of Juvenile Swimming Crab, Portunus trituberculatus

This experiment was conducted to evaluate the effects of different carbohydrate levels on the growth performance, glycogen accumulation in tissue, enzyme activities, and expression levels of genes related to hepatopancreatic glucose and lipid metabolism and insulin signaling pathway in swimming crab, Portunus trituberculatus for 8 weeks. The results indicated that crabs fed with the 60.0 g kg-1 carbohydrate diet exhibited the highest final body weight (FBW), percent weight gain (PWG), and specific growth rate (SGR) among all treatments. FBW, PWG, and SGR significantly decreased when dietary carbohydrate levels exceeded 240.0 g kg-1. Light microscopy results showed that dietary excessive carbohydrate levels will lead to vacuole, hepatopancreatic tubule lysis, and lipid droplets in hepatopancreas. Expression levels of genes involved into glucose transport, glucose and lipid metabolism, and insulin-like metabolism in the hepatopancreas were significantly influenced by dietary carbohydrate levels. In general, the results of present study demonstrated that dietary optimal carbohydrate levels could not only improve PWG and SGR but also influence the expression of genes involved in glucose, lipid, and insulin-like metabolism. The optimal actual carbohydrate level was estimated to be 87.8-98.4 g kg-1 based on broken-line and second-order polynomial regression analysis between PWG against dietary carbohydrate levels for juvenile Portunus trituberculatus.

High-carbohydrate diet altered conversion of metabolites, and deteriorated health in juvenile largemouth bass

To explore the effects of dietary carbohydrate level on nutrients metabolism, largemouth bass juveniles (initial weight, 4.0 ± 0.2 g) were fed three isonitrogenous and isoenergetic diets containing 9.66% (L), 14.32% (M) or 19.11% (H) carbohydrate for 8 weeks. The lowest weight gain (15.75 ± 0.76 g) was observed in group H. Feeding high carbohydrate diet (HCD) led to increased pyruvate (PA), lactic acid (LD), triglyceride (TG) and free fatty acids (NEFA) levels in plasma. Also, HCD enhanced vacuolation, glycogen granule and lipid accumulation in fish liver. Activities of hepatic glycolysis enzymes such as hexokinase, pyruvate kinase and lactate dehydrogenase did not significantly differ among treatments ( P > 0.05). HCD resulted in enhancement of hepatic phosphoenolpyruvate carboxykinase (PEPCK) and lipase (LPS) activities, and increased glycogen and triglyceride (TG) concentrations. Similarly, expression of glucose and lipid metabolism related genes such as glycogen phosphorylase (PYG) and carnitine palmitoyl transferases (CPT1, CPT2) were up-regulated with increasing carbohydrate level. Hepatic catalase (CAT) and glutathione peroxidase (GSH-PX) activities, and total antioxidant capacity (T-AOC) were decreased in HCD group. UPLC-MS metabolomics revealed that glucose metabolism, lipid metabolism, and antioxidant defense system were influenced by dietary carbohydrate level. HCD raised the accumulation of carbohydrate metabolites (phosphohydroxypyruvic acid), unsaturated fatty acids (19( R )-HETE, 9( S )-HPOT, alpha-Linolenic acid and oleic acid), cholesterol, and antioxidant functional substance (oxidized glutathione). Additionally, these differential metabolites were enriched in the metabolic pathways such as galactose metabolism, fructose and mannose metabolism, unsaturated fatty acid biosynthesis, primary bile acid biosynthesis, cholesterol-butyrate metabolism, glutathione metabolism, serine and threonine metabolism. Overall, our results revealed the details of metabolites conversion in juvenile largemouth bass fed HCD. • High-carbohydrate diet (HCD) led to the accumulation of glycogen, lipid droplets and occurrence of vacuolation in liver. • HCD induced antioxidant response through the glutathione antioxidant system. • HCD promoted the conversion of glucose to other carbohydrates, lipids and protein components.

Effects of dietary carbohydrate level on growth performance, innate immunity, antioxidant ability and hypoxia resistant of brook trout Salvelinus fontinalis

Effects of dietary carbohydrate level on growth performance, innate immunity, antioxidant ability and hypoxia resistant of brook trout <i>Salvelinus fontinalis</i>

Effects of dietary carbohydrate levels on growth, body composition, and gene expression of key enzymes involved in hepatopancreas metabolism in mud crab Scylla paramamosain

This study estimated the effects of different dietary carbohydrate levels on growth performance, feed utilization, body composition, and the gene expression of key enzymes involved in hepatopancreas lipogenesis and glucose metabolism in mud crab Scylla paramamosain. Crabs with an initial mean weight of 1.84 ± 0.06 g were used in an 8-week experiment to test five diets (C6, C12, C18, C24, C30) formulated to contain increasing levels of carbohydrate, measured as 8.55%, 13.36%, 17.76%, 25.64% and 32.50%, respectively. The results showed that the levels 25.64% and 32.50% improved growth performance, with the best gains at 25.64%. The highest dietary carbohydrate level led to higher hemolymph glucose concentrations and more fat deposition in the body. Furthermore, real-time quantitative PCR analysis revealed that the mRNA expression of key enzymes in glycolytic and lipogenic metabolism (i.e. glucokinase, fructose-2,6-diphosphatase, and fatty acid synthetase) were significantly affected by the dietary carbohydrate level. The mRNA expression of glucokinase was lowest in the group fed the carbohydrate-rich C30 diet, and the mRNA of fructose-2 and 6-diphosphatase were remarkably expressed in the C24 group (P < .05). The mRNA expression of fatty acid synthase at the dietary carbohydrate levels 32.50% and 25.64% were respectively 10-fold and 5-fold greater than with 8.55% dietary carbohydrate. The overall data suggest that S. paramamosain can be fed 25.64%–32.50% carbohydrate to achieve satisfactory growth performance. A two-slope broken-line regression analysis of weight gain showed that 24.08% dietary carbohydrate would be optimal for this species reared under similar conditions.

Data on PCR primer design for glucose 6-phosphate dehydrogenase gene and the effects of dietary carbohydrate levels on its expression in the liver of Malaysian mahseer (Tor tambroides).

The enzyme glucose-6-phosphate dehydrogenase (G6PD) catalyses the metabolite glucose-6-phosphate in producing NADPH during the first phase of pentose-phosphate pathway thus provides reducing power to all cells for cellular growth, antioxidant defence, and biosynthetic reactions in all living organism. The deliberate inclusion of starch as carbohydrate source in commercial feed however may affect the G6PD hepatic activity in cultured fish. We designed a set of primers to target G6PD gene in the popular Malaysian aquaculture species, Tor tambroides. For this dataset, the molecular characteristics of obtained T. tambroides G6PD (TtG6PD) nucleotide sequence was analysed using multiple alignments and phylogenetic analyses of the deduced amino acids. The set of primers obtained were then used in a study to evaluate the effect of different dietary carbohydrate inclusion levels on the hepatic TtG6PD mRNA expression of the T. tambroides fingerlings. Four groups of fish were given a dietary treatment of 15%, 20%, 25% and 30% starch at the optimal inclusion level of 23.4% for 10 weeks. The TtG6PD mRNA transcripts were measured using real-time-PCR assays and its expression normalized against β-actin, which acts as the internal control gene. This article provides supportive data in relation between hepatic TtG6PD mRNA gene expression in T. tambroides and how it is influenced by its dietary carbohydrate intake. These data will also assist in further nutritional genomic studies of carbohydrate and energy utilization for all species in the mahseer family.

Effect of dietary carbohydrate levels on growth performance, non‐specific immune enzymes and acute response to low salinity and high temperature of juvenile sea cucumber Apostichopus japonicus

Effect of dietary carbohydrate levels on growth performance, non‐specific immune enzymes and acute response to low salinity and high temperature of juvenile sea cucumber <i>Apostichopus japonicus</i>

Effect of dietary carbohydrate levels on the growth of fingerlings of Carnatic carp Barbodes carnaticus (Jerdon 1849)

Fingerlings of Barbodes carnaticus (average size: 9.25 ± 0.43 cm; 7.39 ± 1.18 g) were reared for 60 days in aerated plastic tubs (40 l) providing 5 iso-nitrogenous diets formulated to contain crude NFE (nitrogen free extract) levels ranging from 35 to 50% using pure ingredients. The fish were fed ad libitum and were allowed to feed for 6 h and thereafter the unconsumed feeds were siphoned out. The following day, faecal matter was collected, dried, pooled and stored for proximate analysis. Water from each tub was replaced (50%) with freshwater every day after faecal matter collection. Proximate composition of feed and faecal matter was analysed. Crude fiber was used as the reference marker for dry matter, protein and fat digestibility determination. The growth parameters increased (p&lt;0.05) in B. carnaticus upto dietary NFE levels of 43.72%, beyond which a decrease was noticed. The food conversion ratio (FCR) and protein efficiency ratio (PER) were the best with the diet containing 43.72% NFE. Proximate composition of fish carcass revealed the highest protein and fat contents in those fed the 43.72% NFE diet. Dry matter and NFE digestibility increased with increasing dietary NFE level upto 43.72%, whereas protein digestibility showed a decreasing trend. The study revealed a dietary NFE requirement of around 44% for the fingerlings of B. carnaticus.

Pyruvate kinase genes in grass carp Ctenopharyngodon idella: molecular characterization, expression patterns, and effects of dietary carbohydrate levels.

To explore features of carbohydrate metabolism and evolution of carbohydrate metabolism-associated genes in herbivorous fishes, the open reading frames (ORF) of PKL, PKMa, and PKMb genes of grass carp (Ctenopharyngodon idella) were obtained, encoding 538, 528, and 532 amino acids, respectively. Comparative genomic analysis showed that adjacent PK genes were highly conserved between fish and mammals. Gene expression profiles were quite different between the three PK genes in tissues and at developmental stages. PKL, PKMa, and PKMb had the highest expression levels in the liver, heart, and muscle, respectively. During embryogenesis, high expression levels of PKMa and PKMb were detected in unfertilized and fertilized eggs. Following a non-expression period, PKMa and PKMb exhibited high expressions again after the hatching stage. In contrast, PKL transcripts could not be detected in early developmental stages, and expression levels continued to increase from the hatching stage to 144h post hatching. After the 8-week feeding trial with 18%, 30%, and 42% dietary carbohydrate levels, the concentrations of glucose and insulin in serum, pyruvate kinase enzymes, and gene expression levels in brain, muscle, and liver tissues all increased with the increase in carbohydrate levels in the diets. Furthermore, high carbohydrate levels (30% and 42% carbohydrate diets) had a greater effect on grass carp growth. This indicated that PKL, PKMa, and PKMb genes were not only very important in catalytic enzymes, which can be up-regulated by high carbohydrate dietary conditions, but also exhibited a complex and detailed division of labor in different tissues and developmental stages.

Effect of dietary starch level on growth, metabolism enzyme and oxidative status of juvenile largemouth bass, Micropterus salmoides

A 60-day feeding trial was conducted to investigate the effect of dietary carbohydrate level on the growth performance, body composition,plasma biochemical indices and antioxidant capacity of largemouth bass, Micropterus salmoides. Six isonitrogenous and isolipidic diets containing graded levels of starch (0%, 5%, 10%, 15%, 20% and 25%) were fed to juvenile largemouth bass. The weight gain (WG), specific growth rate (SGR) and protein efficiency ratio (PER) decreased with increasing dietary starch levels (P < .05), whereas feed conversion ratio (FCR) showed the opposite trend. Feed intake (FI) was found to be not significantly related to the dietary starch levels (P < .05). However, liver lipid, hepatic glycogen and muscle glycogen contents increased significantly with dietary starch levels. There were significant differences in hepatic glucose metabolism enzymes in fish fed diets with different dietary starch levels. The hexokinase (HK), glucokinase (GK), and pyruvate kinase (PK) activities in liver increased significantly as dietary starch levels increased, whereas fructose-1,6-bisphosphatase (FBPase), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) activities in liver showed the opposite trend. Moreover, the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and inducible nitric oxide synthase (iNOS) activities, nitric oxide (NO) concent in liver decreased significantly as dietary starch levels increased, while the malondialdehyde (MDA) contents in liver increased. Results demonstrate that the starch levels may affect growth performance and metabolic changes in hepatic intermediary metabolism, which suggest that starch diets were inefficiently used as an energy source by M.salmoides juveniles.

Effect of Dietary Carbohydrate Levels on the Growth and Liver Function of Carp Cyprinus carpio

This experiment was conducted to study the effects of carbohydrate levels on the growth and liver function of Tianjin carp, Cyprinus carpio (mean body weight, 60.82 ± 0.38 g). Three diets, including 30% protein and 5.5% fat (dry matter) and 0, 15, or 30% corn starch (carbohydrate source) were provided to control, low carbohydrate, or high carbohydrate treatment groups, respectively. Weight gain, specific growth rate, hepatopancreas somatic index, and liver glycogen content were significantly higher in fish fed the 30% corn starch diet than fish fed 0% corn starch (P&lt;0.05) but did not differ between the other two treatment groups. Protein efficiency ratio increased significantly as corn starch level increased (P&lt;0.05), but feed conversion ratio showed the opposite trend (P&lt;0.05). Glutamic pyruvic transaminase activity in the serum significantly increased with increasing corn starch levels (P&lt;0.05), but total protein (decreasing trend) and glutamic-oxaloacetic transaminase (increasing trend) did not differ among dietary treatments. Histomorphological analysis of hepatopancreas sections showed that fish fed 15% or 30% corn starch diets presented mild hydropic degeneration and fatty degeneration or severe fatty degeneration, respectively. In summary, although carbohydrates promote carp growth, they enhance glycogen and fat accumulation in the hepatopancreas, reducing its function.

Molecular characterization, expression and activity of glucokinase in golden pompano, Trachinotus ovatus: Response of its expression to carbohydrate in the diet

It is well known that the enzyme glucokinase (GK) plays an important role in the control of glucose homeostasis. In the present study, a glucokinase (To-GK) was cloned from golden pompano, Trachinotus ovatus. The To-GK cDNA is composed of 2151bp with a 33bp of 5′-UTR, 1437bp open reading frame (ORF) and 681bp 3′-UTR, encoding a polypeptide of 478 amino acids (GenBank accession no: ALX36181.1). Phylogenetic analysis revealed that To-GK showed highest similarity to Cynoglossus semilaevis GK. Tissue distribution analysis showed that the highest expression of the To-GK was detected in liver. Then, 8-week feeding trial was conducted to investigate the effects of dietary carbohydrate levels (57.5, 120.4, and 277.7gkg−1) on the activity and mRNA expression of To-GK in T. ovatus. Higher GK activity was found in fish fed 277.7g kg−1 carbohydrate diet. To-GK expression was higher in fish fed the 277.7gkg−1 carbohydrate diet. Overall, our data suggest that the hepatic GK activity and mRNA expression of T. ovatus were up-regulated significantly as dietary carbohydrate levels increased. These results indicated that To-GK plays a crucial role in the adaptation of hepatic glycolysis to dietary high carbohydrates in T. ovatus.