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Both cottonseed meal (CSM) and dried distiller's grains with solubles (DDGS) are important plant protein sources for fish. This study investigated the effects of dietary DDGS inclusion to replace different portions of CSM on growth performance, muscle texture, health status as well as myogenic‐related genes expression of juvenile grass carp (initial weight: 5 g). A 60‐d feeding trial was performed by feeding fish with three isonitrogenous and isoenergetic diets containing different levels of DDGS (0, 10.3% and 20.6%). The highest growth and feed efficiency occurred at 20.6% DDGS dietary inclusion. Body condition factor, hepatosomatic index, serum ALT and AST as well as hepatic GSH and T‐SOD all showed a downward trend with increasing dietary inclusion of DDGS (p <.05). Collagen content in raw muscle increased with DDGS inclusion. However, DDGS inclusion decreased muscle texture indices and muscle fibre density, while increased muscle fibre diameter (p <.05). Dietary DDGS inclusions significantly upregulated the expression of fgf6a, myh1, myh2 and myh4 in muscle, while downregulated the expression of myod, myf5, myog, mrf4, mstn1, fgf6b and myh7. Overall, dietary DDGS replacing CSM positively affects growth by regulating gene expression involved in myogenesis and hypertrophy, while depressed antioxidant capacity. [ABSTRACT FROM AUTHOR]

An 8‐week growth trial was conducted to investigate the effects of dietary Arg levels (7.6, 12.3, 17.9, 22.4 and 28.6 g/kg diet) on growth performance, hepatopancreatic antioxidant capacity, intestinal morphology and growth‐related gene expressions of juvenile grass carp (Ctenopharyngodon idellus). The results showed that SGR in Arg22 and Arg28 groups was lower than in Arg12 and Arg17 groups (p < 0.05). Serum NO content in Arg7 group was lower than other groups. Hepatopancreatic GSH‐Px activity was higher in Arg17 group than in Arg7 group, while MDA content showed the opposite trend. Hepatopancreatic IGF‐1 expression tended to increase with Arg from 7.6 to 22.4 g/kg and then decreased in Arg28 group (p < 0.05), while IGFBP‐1 expression increased with Arg level. Muscle mRNA expressions of TOR and S6K1 showed quadratic trends as dietary Arg level increased, which were higher in Arg17 group than in Arg22 and Arg28 groups (p < 0.05). Higher mRNA expression levels of y+LAT1, y+LAT2 and PepT1, as well as higher villus height and villus width in foregut, were all observed in Arg17 group. The optimal dietary Arg level based on SGR by the quadratic model was 15.3 g/kg diet for juvenile grass carp, corresponding to 54.7 g/kg dietary protein. [ABSTRACT FROM AUTHOR]

A 49-days feeding trial was conducted to study the effects of sodium butyrate on growth performance, gut morphology of juvenile grass carp. Five isoenergetic and isonitrogenous experimental diets were compounded by the supplementation in the basal diet with gradient sodium butyrate at 0, 500, 1000, 2000, 3000 mg kg−1 respectively. A total of 375 juvenile grass carp (with initial body weight of 3.8 g) were randomly allocated into five diet treatments, and each treatment has three replicates. The results showed that the specific growth rate ( SGR) of SB1000 and SB2000 group was significantly higher ( P < 0.05) than that of the other groups. Moreover, the lowest SGR was observed in SB3000 group. Feeding rate and the whole-body proximate composition including moisture, crude lipid, crude protein and crude ash were not affected by sodium butyrate ( P > 0.05). Total superoxide dismutase activities in hepatopancreas in the experimental groups were significantly higher than those in the control group ( P < 0.05). Glutathione peroxidase activity in hepatopancreas was significantly upregulated by dietary sodium butyrate level ( P < 0.05). However, the activity of total antioxidant capacity and the contents of malondialdehyde were not significantly different among groups. The expression levels of mRNA encoding PepT1 and LAT2 in the foregut both showed a first increasing and then decreasing tendency as dietary sodium butyrate level increased ( P < 0.05), and peaked in SB1000 and SB2000 groups respectively. The results indicated that appropriate dietary supplementation of sodium butyrate at 2000 mg kg−1 could improve the growth, antioxidant ability and intestinal absorption capacity of the juvenile grass carp. [ABSTRACT FROM AUTHOR]

Abstract: A growth trial was conducted to investigate the effects of different dietary rapeseed meal level (0, 16%, 32%, 48%, 64%) on growth performance, blood biochemistry and hepatopancreatic histology of grass carp and to determine the optimal rapeseed meal inclusion level in fish diet. Furthermore, an in vitro cell culture was designed to test the cellular toxicity of allyl isothiocyanates (AITC) on liver cells, so as to elucidate the toxic mechanism of glucosinolates on fish. The results showed that SGR (specific growth rate) of fish linearly (P <0.001) decreased as dietary rapeseed meal level increased: SGR=−0.0046∗(rapeseed meal level)+2.2318 (R2 =0.7229), and the highest SGR values were observed in the control and 16% group. Feeding rate of fish was significantly (P <0.05) depressed only in 64% rapeseed meal group. Protein efficiency ratio (PER) values in the 48% and 64% group were significantly (P <0.05) lower than those of the control, 16% and 32% group. Hepatopancreatic lipid contents increased significantly (P <0.05) as dietary rapeseed meal level increased, and the highest values were observed in 32% and 64% groups. BUN content in plasma increased significantly (P <0.05) when dietary rapeseed meal level was at or over 32%. No significant difference was observed in other blood biochemical indices. Histological examination showed that both nuclei migration and lipidic vacuoles in the cytoplasm were observed in 32%, 48% and 64% group, and parenchymal necrosis was also observed in 64% group. Results of liver cell primary culture showed that the viable cells in the control, 10−5 and 10−6 mol/l AITC groups grew adherently. In contrast, viable cells can hardly be observed and the dead cells suspended in the culture medium of the highest concentration (10−2 mol/l) group. The activities of LDH, ALT, AST and MDA concentration in the culture medium changed as the concentration of AITC varied. The mechanism of damages caused by rapeseed meal to fish growth and hepatopancreatic structure and function was further discussed. [Copyright &y& Elsevier]

Fish endure long periods of fasting and demonstrate an extensive capacity for rapid and complete recovery after refeeding. The aim of this study was to investigate the effects of refeeding after fasting on growth, muscle characteristics and the related gene expressions of juvenile grass carp (Ctenopharyngodon idellus). Fish were divided into three groups with triplicates: continuous feeding for 28 days (F28), 14 days of fasting and 14 days of refeeding (S14F14), and continuous fasting for 28 days (S28). Fish were sampled every 7 days for morphological, histological and gene expression analyses. Results showed that fasted fish gained weight continuously during refeeding, displaying compensatory growth. The muscle fiber diameter in S14F14 group decreased gradually during fasting and then increased with refeeding, but didn't reach the value in F28 group on 28d, while the muscle fibers density showed the opposite trend (P < 0.05). Fsih in S14F14 group recovered the intramuscular fat accumulatation during refeeding, accompanied by the upregulated expressions of fas and acc and the downregulated expressions of cpt1 and lpl in muscle on 21d. With the prolongation of fasting time, the expression of several key genes involved in myogenesis (myf5, mrf4, myog, myod, cyclind1) and muscle growth (fst, fgf6a, fgf6b) in S14F14 group decreased firstly and then increased briefly, while igf-II decreased and mstn increased continuously. All genes in S14F14 group eventually reached the same level as those in F28 group at the end of the experiment except fst and fgf6a. In conclusion, this study showed that 14 days of fasting resulted in muscle fiber atrophy in grass carp while refeeding after fasting presented compensatory mass gain, along with a coordinated regulation of several genes involved in a strong resumption of myogenesis to promote muscle growth. These results helped to understand the physiological regulation mechanism of refeeding on muscle growth of fish. • The refeeding after 2-week fasting caused compensatory mass gain of juvenile grass carp. • The muscle fiber diameter decreased gradually during fasting and then increased after refeeding. • Muscle growth in response to feeding regime was regulated through a series of genes involved in myogenesis and hypertrophy. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the biological value between dietary rapeseed meal (RSM) and maize distiller's dried grain with solubles (DDGS) in juvenile grass carp (initial body weight: 5.38 ± 0.18 g) through a 60 d feeding trial. A control diet containing 28% RSM and 4 experimental diets containing 10.0, 20.6, 30.9, and 41.1% DDGS to replace RSM were formulated. The results showed that dietary DDGS inclusion significantly affected the growth performance including final body weight, SGR, FR, and FE, which all showed a quadratic trend as DDGS level increased. The optimal dietary DDGS level was estimated as 28.2% and 32.1%, respectively, based on the quadratic models of SGR and FE. As dietary DDGS level increased, hepatosomatic index decreased linearly (P = 0.000), while condition factor decreased and then increased in a quadratic model (P = 0.020). The mesenteric fat index showed a trend opposite to condition factor responding to DDGS level. Serum ALT, AST, and triglyceride levels decreased linearly with increasing dietary DDGS. As DDGS inclusion level increased, collagen content in raw muscle increased linearly, while muscle texture including hardness, gumminess and chewiness decreased linearly (P = 0.000). Muscle fiber diameter linearly increased with DDGS level (P = 0.000), while fiber density decreased in a quadratic model (P = 0.008). Apparent digestibility coefficients (ADCs) of dry matter and energy decreased at higher DDGS inclusion level (30.9% or more) while ADC of protein increased first and then decreased. The relationship between dietary DDGS inclusion level and expression of fgf6a , myhc, mrf4, mstn, and myf5 were explained by quadratic regression models. fgf6b expression decreased with DDGS level. Overall, Dietary DDGS replacing RSM showed positive effects on growth performance, lipid metabolism and muscle collagen content, while negatively affected hardness of muscle. • DDGS replacing RSM improved growth performance and health status of grass carp. • High DDGS inclusion to replace RSM decreased the dry matter and energy digestion. • Dietary DDGS decreased cooked muscle texture and muscle fiber cellularity. • DDGS affected growth and texture via gene expressions in myogenesis and hypertrophy. [ABSTRACT FROM AUTHOR]

Grass carp (Ctenopharyngodon idellus) is one of the most important aquaculture fish in China. This study tried to explore the effects of dietary alcoholic extract of lotus leaf (AELL) addition on the growth performance and health status of grass carp by feeding juvenile fish (average weight: 34 ± 1 g) with four different experimental diets: control, AELL7, AELL14 and AELL21 for 8 weeks. At the end of the growth trial, the highest values of final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and feed intake (FI) all occurred in group AELL14 (P < 0.05). Compared to control, the crude lipid content of whole-body and the serum malondialdehyde (MDA) in the three experimental groups decreased, while the serum superoxide dismutase (SOD), glutathione peroxidase (GSH) and total antioxidant capacity (T-AOC) values almost all increased in the three experimental groups. The highest serum immunoglobulin M (IgM) concentration occurred in AELL14 group (P < 0.05). In AELL14 and AELL21 groups, both the serum complement 3 (C3) concentration and lysozyme (LYS) activity were significantly higher, whereas the final cumulative mortality in challenge test was significantly lower, when compared to those in control group (P < 0.05). The AELL exerted dose-dependent beneficial effects on grass carp health through up-regulating related gene expressions and enzyme activity. In conclusion, the optimal dietary AELL level is 0.14% for juvenile grass carp. • Lotus leaf extract can improve growth performance and health status of grass carp. • Lotus leaf extract exhibited dose-dependent beneficial effects on grass carp. • Optimal lotus leaf extract inclusion level in the grass carp diet is 0.14%. [ABSTRACT FROM AUTHOR]

Abstract: A growth trial lasting for 12weeks was conducted in a semi flow-through system to determine the dietary potassium requirement of juvenile grass carp (Ctenopharyngodon idellus) with an initial body weight of 4.8g. Seven isonitrogenous and isoenergetic semi-purified diets were compounded with different dietary potassium levels: 1.50, 2.32, 3.28, 5.30, 7.12, 9.45 and 10.44gkg−1 diet. The results showed that specific growth rate and feed efficiency of grass carp were significantly (P <0.05) affected by dietary potassium level, the highest value of specific growth rate was in 5.30gkg−1 group and feed efficiency values in 5.30, 7.12 and 9.45gkg−1 groups were significantly higher than those in the other groups. The survival rate of grass carp in the present study was not affected by dietary potassium level (P >0.05). The Na+–K+ ATPase activity value in the gills varied significantly (P <0.05) with dietary potassium level and showed an increasing and then decreasing trend, and the highest value was in the 7.12gkg−1 group. Dietary potassium level showed significant (P <0.05) effect on serum SOD, ALP and AST activities. SOD and ALP activities increased and then decreased as potassium level increased, while AST decreased first and then increased. Serum TP and TC contents increased and then decreased with potassium level (P <0.05). TG, ALT and BUN were not affected by dietary potassium level (P >0.05). Body potassium and moisture contents increased and lipid content decreased with dietary potassium content, while ash content in fish body increased first and then decreased as potassium content increased (P <0.05). Body protein in the 10.44gkg−1 group was significantly lowered (P <0.05). However, calcium, magnesium, phosphorus and sodium contents in dry matter were not affected by dietary potassium level. When the potassium content of water was 1.86–3.10mgL−1, judging from the polynomial regression analysis for the specific growth rate of fish and the Na+–K+ ATPase activity in the gill, and the broken-line analysis for body potassium content, the optimal dietary potassium content for juvenile grass carp was 4.65, 7.27 and 5.98gkg−1 diet respectively. [Copyright &y& Elsevier]