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A nine-week feeding experiment was conducted in flow-through system with gibel carp (43.8 ± 0.2 g) to study the effects of dietary available phosphorus (P) on growth, phosphorous digestibility and intestinal enzyme activities. Seven semipurified diets were formulated to contain 0.8 (the basal), 2.4, 3.6, 6.1, 7.4, 10.1 and 15.8 g available phosphorus kg−1 diet. The results showed that specific growth rate and feed efficiency increased with increasing dietary available P from 0.8 to 7.4 g P kg−1. Fish body ash increased with increasing dietary available P, while moisture, protein content or energy content had no difference. Total phosphorus waste discharging ( TPW) increased with increased dietary phosphorous. Plasma glucose was higher in the fish fed with 7.4 g kg−1 P. Plasma triglycerides was lower in fish fed diets containing 6.1-10.1 g kg−1 P. No significant effects were observed in plasma P and Ca ( p > .05). The activities of intestinal amylase, lipase and trypsin showed no difference, while AKP and Na+, K+- ATPase activities decreased with increasing dietary available P. In conclusion, based on the regression between specific growth rate ( SGR), P retention efficiency, feed efficiency ( FE) and dietary available P, the available P requirements for on-growing gibel carp were 10.69, 8.22 and 6.72 g kg−1, respectively. [ABSTRACT FROM AUTHOR]

Two 8-week growth trials were conducted in indoor recirculation system to evaluate the protein requirements for juvenile (3.70 ± 0.20 g) and pre-adult (85.2 ± 0.70 g) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets were formulated for each trial using fish meal and casein as protein sources, and protein level was 250-450 g kg−1 in Trial 1 and 200-450 g kg−1 in Trial 2. With the increasing dietary protein, feeding rate ( FR) and feed conversion ratio ( FCR) significantly decreased ( P < 0.05). Weight gain ( WG) increased first and then reached a plateau in 330-450 g kg−1 in Trial 1 ( P > 0.05), while decreased after the maximum value in 350 g kg−1 in Trial 2 ( P < 0.05). Productive protein values ( PPVs) were lower in 370-450 g kg−1 in Trial 1 and 400-450 g kg−1 in Trial 2 ( P < 0.05). Increasing dietary protein level increased protein content and decreased lipid content in whole fish body and white muscle ( P < 0.05). Apparent digestibility coefficient of dry matters ( ADCd) decreased, while apparent digestibility coefficient of protein ( ADCp) increased in 370-450 g kg−1 in Trial 1 and 250-450 g kg−1 in Trial 2 ( P < 0.05). Trypsin activity significantly increased in 370-450 g kg−1 in Trial 1 ( P < 0.05) and was not affected in Trial 2 ( P > 0.05). Hepatic alanine aminotransferase ( ALT) and aspartate aminotransferase ( AST) activities in both trials increased when dietary protein was above 400 g kg−1 ( P < 0.05). Based on quadratic regression of WG, it was estimated that dietary protein requirement for maximum growth was 414 g kg−1 (digestible protein of 376 g kg−1) and 365 g kg−1 (digestible protein of 324 g kg−1) for juvenile (3.70 g) and pre-adult gibel carp (85.2 g). [ABSTRACT FROM AUTHOR]

This study was conducted to determine the effects of dietary cellulase addition on improving the nutritive value of Chlorella for juvenile crucian carp Carassius auratus (initial body weight: 2.99 ± 0.02 g, mean ± SEM). Five isonitrogenous and isoenergetic experimental diets were formulated to contain 0.0 (control), 0.5, 1.0, 1.5 and 2.0 g kg−1 cellulase, respectively. Each experimental diet was randomly assigned to triplicate groups with 25 juvenile fish per fibreglass tank for 8 weeks. The results showed that weight gain, specific growth rate, feed intake and the trypsin activity in the anterior intestine increased with increasing dietary cellulase to 1.5 g kg−1 and then declined with further addition. However, the mRNA expression levels of Mrf4 and Myf5, the apparent digestibility coefficients for dry matter, protein, energy and the majority of amino acids, and the activity of lipase in the anterior intestine were highest in fish fed the 1.0 g kg−1 cellulase diet, and then tended to decline with further cellulase supplementation. In conclusion, the optimal dietary cellulase supplementation level was 1.0-1.5 g kg−1, which can improve growth performance, digestive activities and nutrient digestibility in crucian carp. [ABSTRACT FROM AUTHOR]

In this study, Bacillus natto NT was evaluated for use as a probiotic supplement in the feeds on the growth performance and the growth-related genes' and micro RNAs' (mi RNAs) expression in the skeletal muscle of grass carp ( Ctenopharyngodon idella). Grass carps (ave. wt. 43.96 ± 0.27 g) were fed diets supplemented with 1.87 × 109 (Bn1), 3.73 × 109 (Bn2), 5.60 × 109 (Bn3), 7.47 × 109 (Bn4) and 9.33 × 109 (Bn5) B. natto NT cells per 100 g feed for 56 days. The control group (BnC) was not supplemented with the B. natto NT. The fish of Bn3, Bn4 and Bn5 groups displayed better growth performance and lower feed conversion ratio ( FCR) than the other groups ( P < 0.05). Compared with the fish of BnC group, miR-1a, miR-181a, miR-23a and miR-206 expressions increased ( P < 0.05), and the myostatin and myocyte enhancer factor C ( MEF2C) mRNAs were down-regulated ( P < 0.05) in the fish of Bn4 and Bn5 groups. The specific growth rate analysis and apparent expressional regulation of the growth-related mi RNAs and genes stimulated by B. natto suggest the potential application of B. natto in improving the growth performance on the grass carps. [ABSTRACT FROM AUTHOR]

A 7-week growth trial was conducted to evaluate the effects of dietary soybean meal ( SBM) on digestive enzyme activity of intestinal mucosa, m RNA levels of digestive enzymes in hepatopancreas, and the mid-intestinal and hepatopancreas histology of gibel carp CAS III ( Carassius auratus gibelio). Four different growth phases of gibel carp (initial body weight: fry, 0.8 g; juvenile, 5.0 g; 1-year-old, 62.7 g; and broodstock, 135.6 g) were tested. Seven isonitrogenous and iso-energetic diets were formulated to contain different SBM replacement levels (0%, 20%, 40%, 60%, 80% and 100% of dietary fish meal protein), and another diet ( SBMAA) contained all SBM protein and supplied crystalline amino acids. The results showed that the activities of mid-intestine trypsin, α-amylase and gamma glutamyl transpeptidase reduced with increased dietary SBM, while the chymotrypsin activity increased first and then decreased. The ultrastructures of intestinal epithelial cells and hepatopancreas cells in fry and broodstock fish were distinctly affected by 200 g kg-1 dietary SBM. Supplementation of dietary amino acid to the highest replacement groups was not sufficient to improve digestive and absorptive capacities and growth performance. Gibel carp may be adapted to dietary SBM through increase in gene expression of hepatopancreas digestive enzymes and has potential to utilize proceeded SBM as feedstuffs. [ABSTRACT FROM AUTHOR]

Four 70-day growth trials were performed to investigate the effects of substitution of dietary fishmeal ( FM) by soya bean meal ( SBM) in different sizes of gibel carp CASIII ( Carassius auratus gibelio). The initial weights of fry, juvenile, 1-year fish and broodstock of gibel carp were 0.8, 5.0, 62.7 and 135.6 g, respectively. In each trial, eight diets were formulated to be iso-nitrogenous and iso-energetic, and different levels of soy bean meal protein were used to replace fishmeal protein at 0%, 20%, 40%, 60%, 80% and 100%. Another diet containing all SBM protein and supplemented with crystalline amino acids was also tested. The results showed that apparent digestibility coefficients ( ADCs) of dry matter and energy decreased with SBM substitution while the ADCs of phosphorus increased. The ADCs of protein of high SBM substitution were higher than those of FM groups. Juveniles show lower ADCs than grown-up fish. Dietary SBM substitution showed negative effects on survival, growth and feed utilization in gibel carp. One-year fish and broodstock gibel carp have relatively higher tolerance to dietary SBM than fry and juveniles. [ABSTRACT FROM AUTHOR]

A 60-day trial was conducted in a recirculation system to determine the responses of herbivorous grass carp ( Ctenopharyngodon idellus) (0.43 g), omnivorous gibel carp ( Carassius auratus gibelio CAS III) (0.46 g) and carnivorous black carp ( Mylopharyngodon piceus) (0.46 g) when fed with fishmeal ( FM)- or soybean meal ( SBM)-based diets. Two isonitrogenous (380 g kg−1 DM), isolipid (80 g kg−1 DM), isocaloric (17.75 kJ g−1) diets were formulated using FM and SBM as main protein sources. The results showed that weight gain ( WG), feed efficiency ( FE) and protein retention efficiency ( PRE) in FM group were significantly higher than those in SBM group. Grass carp showed better utilization on SBM than other two species and presented higher WG, FE and PRE. When fed with SBM diet, intestinal chymotrypsin ( CHY), lipase and trypsin ( TRY) activities of gibel carp and black carp decreased while higher α-amylase (α- AMY) activity of grass carp increased. An enteritis-like effect was observed in black carp and grass carp fed SBM diet. Intestine bacteria mainly belonged to Firmicutes in gibel carp and Proteobacteria in black carp. The dominant genera identified in three species were Cellulomonas, belonging to Actinobacteria. In conclusion, SBM decreased the growth of three carps. Grass carp was more adapted to plant protein. [ABSTRACT FROM AUTHOR]

An 11-week growth trial was conducted to determine dietary myo-inositol ( MI) requirement for juvenile gibel carp ( Carassius auratus gibelio). Myo-inositol was supplemented to the basal diet to formulate six purified diets containing 1, 56, 107, 146, 194 and 247 mg MI kg−1 diet, respectively. Each diet was fed to triplicate groups of juvenile gibel carp (initial body weight 3.38 ± 0.27 g, mean ± SD) in a flow-through system. The diets were randomly assigned to different fish tanks. Fish fed ≥ 107 mg MI kg−1 diet had significantly higher weight gain ( WG), feed efficiency ( FE) and protein efficiency ratio than those fed 1 mg MI kg−1 diet. Fish fed ≥ 56 mg MI kg−1 diet had higher feeding rate and survival compared with fish fed 1 mg MI kg−1 diet. Dietary supplemental inositol did not affect fish liver inositol concentration. Fish fed ≥ 56 mg MI kg−1 diet had higher body dry matter, crude protein and gross energy and lower hepatosomatic index than fish fed 1 mg MI kg−1 diet. Dietary inositol supplementation decreased fish body ash. Quadratic regression of weight gain indicated that the myo-inositol requirement to maximum growth for juvenile gibel carp was 165.3 mg MI kg−1 diet. [ABSTRACT FROM AUTHOR]

A 75 days experiment was conducted in a flow-through system on juvenile gibel carp ( Carassius auratus gibelio) (3.43 ± 0.01 g) to evaluate the effects of dietary lysozyme on growth performance, intestine morphology, microbiota and immune response. Four isonitrogenous (crude protein: 367 g kg−1) isolipid (62 g kg−1) and isocaloric (gross energy: 17.92 kJ g−1) diets were formulated to contain 0, 100, 500 and 1000 mg kg−1 lysozyme, respectively. The results showed that specific growth rate (SGR) and feed efficiency (FE) increased at 1000 mg kg−1 lysozyme. Blood leucocyte phagocytic activity (PA) and serum lysozyme (LZM) decreased with dietary lysozyme on day 25, 50 and 75. There were no significant differences in alternative complement pathway (ACP), respiratory burst (ROS), serum superoxide dismutase (SOD), glutathione peroxidase (GSHpx) or malonaldehyde (MDA). After Aeromonas hydrophilia challenge, higher survival was obtained at 500 mg kg−1 group. PA, ROS, SOD, LZM and ACP increased with increasing dietary lysozyme, while MDA reversed. Goblet cells in mid-intestine and microvilli height in distal intestine increased with dietary lysozyme on day 75. Dietary lysozyme reduced the diversity of intestine microbiota. In conclusion, oral administration of 500 mg kg−1 dietary lysozyme for 75 days is recommended for the survival of gibel carp and 1000 mg kg−1 dietary lysozyme for fast growth. [ABSTRACT FROM AUTHOR]

A 10-week feeding trial was conducted in a flow-through system to determine dietary choline requirement for juvenile gibel carp ( C arassius auratus gibelio) (5.5 ± 0.1 g). Purified basal diet was formulated using vitamin-free casein as protein source. Choline chloride was supplemented to the basal diet to formulate seven diets containing 76.1, 163, 356, 969, 1457, 2024 and 4400 mg kg−1 choline. Dietary methionine was 0.58%, less than the requirement (0.69%). The results indicated that specific growth rate ( SGR) was higher in the fish fed 2024 mg kg−1 diet than the control group. Feeding rate and feed efficiency were not significantly affected. Protein productive value increased as dietary choline increased from 76.1 to 2024 mg kg−1 diet and was lower in the fish fed the diet containing 4400 mg choline kg−1 diet. Serum high-density lipoprotein cholesterol ( HDL- C) and total cholesterol significantly increased with increasing dietary choline up to 1457 mg kg−1, and no differences were found with further increase. Fish carcass fat contents decreased significantly with increased dietary choline. Hepatic lipid contents increased with dietary choline up to 1457 mg kg−1 and then decreased. Quadric regression of SGR and plasma HDL- C indicted dietary choline requirement was 2500 and 2667 mg kg−1 diet, respectively. [ABSTRACT FROM AUTHOR]

Gibel carp ( Carassius auratus gibelio) of mean initial weight 3.1 g were fed one of seven casein-dextrin-based diets containing graded levels of magnesium (Mg) (39, 120, 220, 380, 700, 1600 and 2900 mg kg−1) for 3 months with the waterborne Mg concentration of 10.6-12.7 mg L−1. Magnesium sulphate was used as the supplementation Mg source in the diets. The experiment was carried out in a flow-through system. Growth, survival rate, Na+/K+-ATPase, Mg2+-ATPase and tissue mineral contents were measured to investigate the effect of dietary magnesium in gibel carp. At the end of the experiment, the hepatopancreas of fish were collected for enzyme determination. The hepatopancreas, vertebrae and whole body were collected for tissue magnesium content analysis. After 3 months, dietary magnesium supplementation did not improve the growth performance, including feed intake, weight gain and feed conversion efficiency of juvenile gibel carp. On the contrary, negative impacts on survival, reduced growth performance and dramatically decreased Na+/K+-ATPase, Mg2+-ATPase and superoxide dismutase activities were observed in gibel carp fed a high Mg diet of 2900 mg kg−1. Although serum and hepatopancreas Mg and Ca contents were not affected by dietary Mg supplementation, vertebrae and whole-body Mg contents increased significantly with the increasing dietary Mg concentrations. Based on the relationship between whole-body Mg retention and dietary Mg concentration, a suitable dietary Mg level of 745 mg kg−1 could be estimated for gibel carp. It could be concluded that dietary Mg supplementation did not improve the growth performance, but could increase vertebrae Mg contents of gibel carp. Considering the adverse effects, a dietary Mg concentration of above 2900 mg kg−1 is not recommended and it should be careful to supplement magnesium in practical diets for gibel carp as most feed ingredients contain high magnesium concentrations. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to determine lysine requirement of juvenile yellow catfish ( Pelteobagrus fulvidraco) by feeding formulated diets containing crystalline l-lysine. Six isonitrogenous and isoenergetic diets (405 g kg−1 protein, 18 kJ g−1 gloss energy) containing fish meal together with soybean protein concentrate as protein sources and fish oil together with soybean oil as lipid sources were formulated. Crystalline l-lysine was added into the six diets to acquire lysine concentrations of 17.3, 21.8, 26.0, 31.3, 35.5 and 41.9 g kg−1 dry diets, respectively. Mixture of crystalline amino acid was supplemented to simulate the amino acid profile in muscle of yellow catfish. The results indicated that final body weight (FBW), weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency (PE) increased with the increase in dietary lysine level from 17.3 to 31.3 g kg−1 of diet and then decreased as the dietary lysine levels further increased. No significant difference in survival rate was found among all the dietary treatments. One-slope, quadratic broken-line analysis on the basis of SGR showed that the dietary l-lysine requirement of juvenile yellow catfish was 33.1 g kg−1 of dry diet (83.2 g kg−1 of dietary protein). [ABSTRACT FROM AUTHOR]

A 21-day growth trial was undertaken to investigate the effect of water temperature (25, 28, 31, 34, 37 °C) on growth, feed utilization and energy budget of juvenile Nile tilapia ( Oreochromis niloticus) (initial body weight around 12 g) with four replicates at each temperature. Feed intake energy (IE), recovered energy (RE), faecal energy (FE), excretory energy (UE + ZE) and heat energy (HE) were calculated to obtain the energy budget. The results showed that feeding rate and ammonia excretion were not significantly affected by water temperature. Specific growth rate in wet weight (SGRw) and FE was significantly lower in the fish reared at 37 °C while no significant difference was observed between the fish reared at 25-34 °C. Protein retention efficiency was highest at 28 °C and lowest at 37 °C. The proportion of IE channelled into RE and UE + ZE was lower while those lost in HE was higher in the fish reared at 37 °C. The optimal growth temperature was estimated as 30.1 °C based on the regression of SGR and water temperature. Energy budget at maximum growth (34 °C) was: 100 IE = 27.0 RE + 1.1 (ZE + UE) + 10.6 FE + 59.2 HE. HE accounted for 69.3% and RE for 30.7% of metabolizable energy. [ABSTRACT FROM AUTHOR]

A 12-week growth trial was conducted with gibel carp Carassius auratus gibelio (initial weight: 2.69 g) to evaluate the effects of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) on growth performance and tissue fatty acid composition. Five diets of different n-3 HUFA levels from 0 to 17 g kg diet were supplemented at 80 g kg dietary lipid by including fish oil (FO) at 0, 25, 50, 75 and 100% of supplemental lipid. The remainder was coconut oil. The results showed that fish fed FO and FO obtained highest specific growth rate and lowest with FO. Feed efficiency was highest at FO and lowest at FO. Apparent digestibility coefficient of lipid increased with increasing dietary n-3 HUFA. The fish fed FO diet had the lowest thiobarbituric acid reactive substance in serum and muscle and highest moisture and lowest lipid content in viscera. Fatty acid compositions of muscle and liver were correlated with dietary fatty acids. Fish muscle concentration of 20:5n-3 increased with increasing dietary n-3 HUFA while the concentration of 22:6n-3 was distinctly reduced in FO group. It suggested that 4 g kg n-3 HUFA in diet could permit gibel carp normal growth performance and provide considerable n-3 HUFA in fish muscle. Excessive n-3 HUFA showed impact on growth performance of gibel carp. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to investigate the effect of supplemental dietary zinc sources on the growth performance and carbohydrate utilization of juvenile tilapia Smith 1840, Oreochromis niloticus × O. aureus. The goal was to compare the bioavailability of two zinc sources, zinc sulphate (ZnSO) or zinc methionine (ZnMet), by using two practical basal diets with 350 g kg (C350) or 400 g kg (C400) carbohydrates based on wheat as the carbohydrate source. The results showed that fish fed with a diet supplemented with 60 mg kg Zn from either ZnSO or ZnMet had a significantly ( P < 0.05) greater specific growth rate and protein efficiency ratio than those fed with the diets of ≤30 mg kg Zn. The composition of tilapia carcass was also found to be influenced by various levels of dietary zinc from the two zinc sources. The G6P-DH in fish fed with the 20 mg kg ZnMet diet and the PK levels in fish fed with 20 mg kg ZnSO and 30 mg kg ZnMet diet were significantly ( P < 0.05) higher than those in fish fed with the C400 diet. The data suggest that supplemental dietary zinc from either ZnMet or ZnSO significantly affects the growth performance and carbohydrate utilization of tilapia. [ABSTRACT FROM AUTHOR]

A 8-week feeding experiment was conducted to evaluate the effect of different dietary protein and lipid levels on growth and energy productive value of juvenile Litopenaeus vannamei, at 30 and 2 ppt, respectively. Nine practical diets were formulated to contain three protein levels (380, 410 and 440 g kg−1) and three lipid levels (60, 80 and 100 g kg−1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The effects of salinity and an interaction between dietary protein level and lipid level on growth and energy productive value of shrimp were observed under the experimental conditions of this study. At 30 ppt seawater, shrimp fed with 440 g kg−1protein diets had significantly higher weight gain (WG) than those fed with 380 g kg−1 protein diets at the same dietary lipid level, and the 60 g kg−1 lipid group showed higher growth than 80 g kg−1and 100 g kg−1 lipid groups at the same dietary protein level. At 2 ppt seawater, the growth of shrimp was little affected by dietary protein treatments when shrimp fed the 80 and 100 g kg−1 lipid, shrimp fed the 80 g kg−1 lipid diets had only slightly higher growth than that fed 60and 100 g kg−1 lipid diets when fed 380 and 410 g kg−1 dietary protein diets. A significant effect of salinity on growth of shrimp was detected with the growth responses at 30 ppt > 2ppt ( P < 0.05). Final body lipid content, body protein content and energy productive value of shrimp was significantly higher in animals exposed to 30 ppt than in shrimp held at 2 ppt. [ABSTRACT FROM AUTHOR]

The effects of aflatoxin B1 (AFB1) on growth, physiological responses and histological changes were investigated in juvenile gibel carp ( Carassius auratus gibelio). Triplicate groups of gibel carp (3.53 ± 0.02 g) were fed seven semipurified diets (Diet 1 to 7) containing 3.20, 5.37, 7.08, 9.55, 12.70, 17.90 and 28.60 μg AFB1 kg−1 diet for 3 months. The results showed fish weight gain fed Diet 6 was 112.6% of that of control group (Diet 1) after 3 months, but there was no significant difference of weight gain between fish fed Diet 7 and the control group. Alanine aminotransferase (ALT) of fish hepatopancreas fed Diet 7 was significantly higher than the control group ( P < 0.05), but no significant difference was observed in ALT activities of the fish fed with more than 10 μg AFB1 kg−1 (Diet 4, 5, 6 and 7). No significant histological lesions were identified between the control and increasing AFB1 treatments. AFB1 accumulated in hepatopancreas was logarithmically related to the dietary AFB1 levels, and AFB1 also accumulated in muscles and ovaries of gibel carp fed Diet 3 to Diet 7. The present results indicated that fish fed with more than 10 μg AFB1 kg−1 diet showed impaired physiological responses and more AFB1 residue of muscles and ovaries above the safety limitation of European Union. [ABSTRACT FROM AUTHOR]

A 68-day growth trial was conducted in a flow-through system to determine the effect of dietary manganese levels on growth and tissue manganese concentration of juvenile gibel carp ( Carassius auratus gibelio). Seven purified diets containing 7.21, 8.46, 9.50, 10.50, 13.03, 19.72 and 22.17 mg manganese (as manganic sulfate) per kilogram diet were fed to triplicate groups of fish (initial weight 3.21 ± 0.01 g). The results showed that dietary manganese levels did not significantly affect feed intake of the fish. Specific growth rate, feed efficiency, total hepatic superoxide dismutase activity, carcass and skeletal manganese concentration increased significantly with increased dietary manganese( P < 0.05) while condition factor decreased significantly( P < 0.05). It was concluded that dietary requirement of manganese was 13.77 mg Mn per kilogram diet. Carcass and skeletal manganese concentration could also be used to evaluate the manganese requirement. Total hepatic superoxide dismulase activity was not a sensitive indicator for dietary requirement. [ABSTRACT FROM AUTHOR]

Triplicate groups of gibel carpCarassius auratus gibelio(initial body weight: 5.25 ± 0.02 g) were fed for 8 weeks at 20–25 °C on five isonitrogenous (crude protein: 400 g kg−1) and isoenergetic diets (gross energy: 17 kJ g−1). Meat and bone meal (MBM) or poultry by-product meal (PBM) were used to replace fish meal at different levels of protein. The control diet contained fish meal as the sole protein source. In the other four diets, 150 or 500 g kg−1 of fish meal protein was substituted by MBM (MBM15, MBM50) or PBM (PBM15, PBM50). The results showed that feeding rate for the MBM50 group was significantly higher than for other groups except the PBM50 group (P < 0.05). Growth rate in the MBM15 group was significantly higher than that in the control (P < 0.05), while there was no significant difference in growth between the control and other groups (P > 0.05). Feed efficiency and protein efficiency ratio in MBM50 was significantly lower while that in MBM15 was significantly higher (P < 0.05). Replacement of fish meal by MBM at 500 g kg−1 protein significantly decreased apparent dry matter digestibility (ADCD) and gross energy (ADCE) while apparent protein digestibility (ADCP) was significantly decreased by the replacement of MBM or PBM (P < 0.05). The results suggest that MBM and PBM could replace up to 500 g kg−1 of fish meal protein in diets for gibel carp without negative effects on growth while 150 g kg−1 replacement by MBM protein improved feed utilization. [ABSTRACT FROM AUTHOR]

The effects of aflatoxin B1 (AFB1) on growth, physiological responses and histological changes were investigated in juvenile gibel carp ( Carassius auratus gibelio). Triplicate groups of gibel carp (3.53 ± 0.02 g) were fed seven semipurified diets (Diet 1 to 7) containing 3.20, 5.37, 7.08, 9.55, 12.70, 17.90 and 28.60 μg AFB1 kg−1 diet for 3 months. The results showed fish weight gain fed Diet 6 was 112.6% of that of control group (Diet 1) after 3 months, but there was no significant difference of weight gain between fish fed Diet 7 and the control group. Alanine aminotransferase (ALT) of fish hepatopancreas fed Diet 7 was significantly higher than the control group ( P < 0.05), but no significant difference was observed in ALT activities of the fish fed with more than 10 μg AFB1 kg−1 (Diet 4, 5, 6 and 7). No significant histological lesions were identified between the control and increasing AFB1 treatments. AFB1 accumulated in hepatopancreas was logarithmically related to the dietary AFB1 levels, and AFB1 also accumulated in muscles and ovaries of gibel carp fed Diet 3 to Diet 7. The present results indicated that fish fed with more than 10 μg AFB1 kg−1 diet showed impaired physiological responses and more AFB1 residue of muscles and ovaries above the safety limitation of European Union. [ABSTRACT FROM AUTHOR]

Excessive carbohydrate intake leads to metabolic disorders in fish. However, few literatures have reported the appropriate carbohydrate level for zebrafish, and the metabolic response to dietary carbohydrate remains largely unknown in zebrafish. This study assessed the responses of zebrafish and zebrafish liver cell line (ZFL) to different carbohydrate levels. In vivo results showed that ≥30% dietary dextrin levels significantly increased the plasma glucose content, activated the expression of hepatic glycolysis-related genes, and inhibited the expression of hepatic gluconeogenesis-related genes in zebrafish. Oil red O staining, triglyceride content, and Hematoxylin-Eosin staining results showed that dietary dextrin levels of ≥30% significantly increased lipid accumulation and liver damage, as well as processes related to glycolipid metabolism and inflammation in zebrafish. In ZFL, the transcription factor sterol regulatory element binding protein-1c signal intensity, 4,4-difluoro-1,3,5,7,8-pentamethyl-4-bora-3a,4a-diaza-s-indacene (BODIPY 493/503) signal intensity, and triglyceride content were also significantly increased when incubated in high glucose, along with abnormal glycolipid metabolism and increased inflammation-related genes. In conclusion, we demonstrated that the maximum dietary carbohydrate level in adult zebrafish should be less than 30%. Excess dietary carbohydrates (30%-50%) caused hepatic steatosis and damage to zebrafish, similar to that seen in aquaculture species. Thus, this study assessed responses to different carbohydrate levels in zebrafish and illustrated that zebrafish is an optimal model for investigating glucose metabolism in some aquatic animals., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Longwei Xi et al.)

To assess the effect of dietary selenium (Se) sources on the meat quality and antioxidant capacity of yellow catfish ( Pelteobagrus fulvidraco ), sodium selenite (Na 2 SeO 3 ), Se yeast, and selenium-enriched Spirulina platensis (Se-SP) were supplemented in the control diet at 0.30 mg Se/kg feed to formulate four diets. The experimental period lasted 50 days. The results showed that Se levels in the plasma, liver, muscle, and whole body were significantly increased by dietary Se yeast supplementation ( P < 0.05) but showed no change in response to Na 2 SeO 3 ( P > 0.05). The three types of Se all increased the firmness and decreased the fracturability of the muscles ( P < 0.05), but only Na 2 SeO 3 resulted in higher springiness, flexibility, stringiness, and stickiness ( P < 0.05). In addition, the muscle n -3 polyunsaturated fatty acid (PUFA) content was increased by Se yeast ( P < 0.05). Regarding antioxidant capacity, dietary Se yeast and Se-SP supplementation improved hepatic glutathione peroxidase activity but decreased hepatic malondialdehyde content ( P < 0.05). Given these results, Se yeast was found to be the optimal source of Se for yellow catfish for higher tissue retention, antioxidant capacity, and PUFA levels. Dietary Se is an effective way to regulate the meat quality and antioxidant capacity of yellow catfish., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Zheng Chen et al.)

The present study investigated the sequential regulation signals of high-carbohydrate diet (HCD)-induced hepatic lipid deposition in gibel carp ( Carassius gibelio ). Two isonitrogenous and isolipidic diets, containing 25% (normal carbohydrate diet, NCD) and 45% (HCD) corn starch, were formulated to feed gibel carp (14.82 ± 0.04 g) for 8 weeks. The experimental fish were sampled at 2 nd , 4 th , 6 th , and 8 th week. In HCD group, the hyperlipidemia and significant hepatic lipid deposition (oil red O area and triglyceride content) was found at 4 th , 6 th , and 8 th week, while the significant hyperglycemia was found at 2 nd , 4 th , and 8 th week, compared to NCD group ( P < 0.05). HCD induced hepatic lipid deposition via increased hepatic lipogenesis ( acc , fasn , and acly ) but not decreased hepatic lipolysis ( hsl and cpt1a ). When compared with NCD group, HCD significantly elevated the hepatic sterol regulatory element binding proteins 1 (SREBP1) signals (positive hepatocytes and fluorescence intensity) at 4 th , 6 th , and 8 th week ( P < 0.05). The hepatic SREBP1 signals increased from 2 nd to 6 th week, but decreased at 8 th week due to substantiated insulin resistance (plasma insulin levels, plasma glucose levels, and P-AKT Ser473 levels) in HCD group. Importantly, the hepatic carbohydrate response element binding protein (ChREBP) signals (positive hepatocytes, fluorescence intensity, and expression levels) were all significantly elevated by HCD-induced glucose-6-phosphate (G6P) accumulation at 2 nd , 4 th , 6 th , and 8 th week ( P < 0.05). Compared to 2 nd and 4 th week, the hepatic ChREBP signals and G6P contents was significantly increased by HCD at 6 th and 8 th week ( P < 0.05). The HCD-induced G6P accumulation was caused by the significantly increased expression of hepatic gck , pklr , and glut2 ( P < 0.05) but not 6pfk at 4 th , 6 th , and 8 th week, compared to NCD group. These results suggested that the HCD-induced hepatic lipid deposition was mainly promoted by SREBP1 in earlier stage and by ChREBP in later stage for gibel carp. This study revealed the sequential regulation pathways of the conversion from feed carbohydrate to body lipid in fish., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Yulong Gong et al.)

To investigate the effects of different dietary protein sources on the reproductive performance of female broodstock, yellow catfish ( Pelteobagrus fulvidraco ) were fed with three experimental diets using fishmeal (FM), soybean meal (SBM), and rapeseed meal (RSM) as main protein sources, respectively. Females (initial weight: 64.56 ± 0.45 g) were distributed into 9 net cages for feeding trial. Results indicated that 30% dietary SBM improved the reproductive performance for higher gonadosomatic index (GSI), relative fecundity, total egg production, egg diameter, and hatching rate. In addition, SBM and RSM diets resulted in higher estradiol (E2), vitellogenin (VTG), luteinizing hormones (LH), and lower follicle-stimulating hormone (FSH) and testosterone (T) in plasma ( P < 0.05) of female broodstock. Dietary SBM and RSM also resulted in lower mesenteric fat index (MFI), plasma total cholesterol (TC), plasma total bilirubin (T-Bil) contents, and gonadal cortisol concentrations, while dietary SBM downregulated the transcription levels of steroidogenesis-related proteins by negative feedback ( P < 0.05). The results demonstrated that dietary SBM and RSM could promote sex steroid hormone and VTG biosynthesis and showed hypocholesterolemic effects. Besides, 30% dietary SBM inclusion could improve the reproductive performance of female yellow catfish broodstock., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2023 Zheng Chen et al.)

An 8-week feeding trial was conducted to evaluate the application of common carbohydrate sources, cornstarch (CS), wheat starch (WS), and wheat flour (WF), to different gibel carp genotypes, Dongting, CASIII, and CASV. The results of the growth and physical responses were analysed by data visualization and unsupervised machine learning. As revealed by a self-organizing map (SOM) and the cluster of growth and biochemical indicators, CASV had superior growth and feed utilization and better regulation of postprandial glucose, followed by CASIII, while Dongting showed a high level of plasma glucose with poor growth performance. CS, WS, and WF were differently utilized by the gibel carp, and WF was associated with greater zootechnical performance based on higher specific growth rate (SGR), feed efficiency (FE), protein retention efficiency (PRE), and lipid retention efficiency (LRE), induced hepatic lipogenesis, increased liver lipids, and enhanced muscle glycogen. Spearman's correlation analysis of the physiological responses indicated that plasma glucose had a significantly negative correlation with growth, feed utilization, glycogen storage, and plasma cholesterol level, and it was positively related to liver fat content in gibel carp. Transcriptional variabilities were observed: CASIII showed increased expression of pklr , which is involved in hepatic glycolysis, and pck and g6p , which are involved in gluconeogenesis. Interestingly, Dongting showed upregulation of genes involved in glycolysis and fatty acid oxidation in muscle. Furthermore, there were numerous interactions between carbohydrate sources and strains for growth, metabolites, and transcriptional control, confirming the existence of genetic polymorphisms in carbohydrate use in gibel carp. Globally, CASV showed relatively better growth and carbohydrate utilization, and wheat flour seemed to be more efficiently utilized by gibel carp., Competing Interests: This work has no conflict of interest., (Copyright © 2023 Xuerong Song et al.)