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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]

A 75-day experiment was conducted with juvenile gibel carp ( Carassius auratus gibelio) (4.80 ± 0.01 g) to evaluate effects of dietary chitosan on fish growth performance, haematology, intestine morphology and immune response. Six isonitrogenous (crude protein: 383 g kg−1), isolipid (97.5 g kg−1) and isocaloric (gross energy: 16.7 kJ g−1) diets were formulated to contain 0, 1800, 4000, 7500, 10 000, 20 000 mg kg−1 chitosan, respectively. The results showed that the growth was depressed when the fish fed with 10 000 mg kg−1 chitosan. Serum cholesterol, triglyceride and low-density lipoprotein decreased in 10 000 and 20 000 mg kg−1 chitosan. On day 75, blood leucocyte phagocytic activity respiratory burst and alternative pathway of complement haemolytic activity were enhanced in 4000 mg kg−1 chitosan. The number of goblet cell, intraepithelial lymphocyte of mid-intestine and microvilli height of distal intestine increased at 4000 mg kg−1 dietary chitosan. Dietary chitosan modulated intestine microbiota, depressed pathogen bacteria Aeromonas veronii-like and improved Cellulomonas hominis-like, Bacillus oceanisediminis-like and two uncultured bacterium-like species on day 75. Dietary 7500 and 10 000 mg kg−1 chitosan enhanced the protection against Aeromonas hydrophila infection. In conclusion, oral administration of dietary 7500 mg kg−1 chitosan for 75 days is recommended for the survival of gibel carp. [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]

Toxicity of aflatoxin B (AFB) was investigated in juvenile hybrid sturgeon Acipenser ruthenus ♂ × A. baeri♀, an important coldwater finfish farmed in China and other countries. Seven experimental diets (Diet A-G) containing different levels of AFB (0, 1, 5, 10, 20, 40 and 80 μg kg diet) were fed to juvenile sturgeon weighing 10.53 ± 0.17 g kg to determine its effect on survival, growth, feed consumption, hematocrit, liver histology as well as muscular and hepatic toxin accumulation. The experiment lasted for 35 days and was conducted in two periods of 25 and 10 days each. No external changes or unusual behaviour was observed in the fish fed diets with AFB. Mortality was observed in fish fed with highest levels of AFB (80 μg kg- Diet G) from day 12 onwards. After 25 days, fish fed the diet of 80 μg AFB kg showed significant lower survival (50 ± 5.77%) followed by those fed 40 μg AFB kg diet (80 ± 5.77%) and 20 μg AFB kg diet (86.66 ± 3.33%). No significant difference was observed in specific growth rate (SGR) or hepatosomatic index (HSI) between groups. Hematocrit was significantly higher in the fish fed the diet of highest AFB. The fish were weighed at day 25 in some treatments (Diets F and G) because of high mortality. However, feeding was continued for another 10 days to observe mortality or behavioural changes if any in the other groups. After 35 days, survival in the fish fed Diet F (40 μg AFB kg) was 40% and those fed Diet E (20 μg AFB kg) was 36.2%. Significant histopathological changes including nuclear hypertrophy, hyperchromasia, extensive biliary hyperplasia, focal hepatocyte necrosis and presence of inflammatory cells were observed in the liver of fish fed high levels of aflatoxin (40 and 80 μg kg). AFB accumulation in fish muscle and liver increased with increased dietary AFB levels. It could be confirmed that 10 μg AFB kg diet was the maximum allowable level in hybrid sturgeon diet. [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]

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]

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]

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]

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]

Two trials were conducted to investigate protein requirements of juvenile (3.18 g in Trial 1) and on-growing (87.1 g in Trial 2) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets containing 250-500 g kg−1 dietary protein were formulated using soy protein concentrate ( SPC) and casein as protein sources. The results showed that weight gain ( WG) increased when dietary protein increased from 250 to 400 g kg−1 and decreased at 400 to 500 g kg−1 CP in Trial 1, while WG increased when dietary protein increased from 250 to 350 g kg−1 and kept constant at 350 to 500 g kg−1 CP in Trial 2. With increasing dietary protein, feed conversion ratio ( FCR) decreased, while protein retention efficiency ( PRE) decreased in Trial 1 and was not affected in Trial 2. Apparent digestibility coefficient of protein ( ADCp) increased with increasing dietary protein in two trails. Trypsin activity increased with dietary protein in the juveniles and was not affected in on-growing fish. Hepatic alanine aminotransferase ( ALT) and aspartate aminotransferase ( AST) activities increased with dietary protein. Broken-line and quadratic regression of WG estimated that dietary protein requirements for maximum growth were about 402-427 g kg−1 for the juvenile and 337-418 g kg−1 for on-growing gibel carp. [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]

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]

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 65-day growth trial was conducted at 19.5 °C to determine the optimal dietary methionine for juvenile rockfish, Sebastes schlegeli. Semipurified diets were formulated to be isonitrogenous and isoenergetic. Fish meal was used as intact protein source and crystal amino acid was used as a part of dietary protein. Six experimental diets were formulated to contain 5.8, 10.8, 15.8, 20.8, 25.8 and 30.8 g kg−1 dietary methionine. The results showed that dietary methionine significantly affected specific growth rate, weight gain, food conversion ratio, protein productive value (PPV), energy retention efficiency, carcass index and body composition. No significant difference was found in hepatosomatic index. The dietary methionine requirement for maximum growth was 13.7 g kg−1 dry matter or 28.0 g kg−1 of dietary protein when cystine content was 1.2 g kg−1 dry matter. [ABSTRACT FROM AUTHOR]

A 11-week growth trial was conducted in a flow-through system with juvenile gibel carp Carassius auratus gibelio to evaluate the effects of gradual replacement of fish meal (FM) by meat and bone meal (MBM) on growth performance, phosphorus (P) and nitrogen (N) loading. Six isonitrogenous (crude protein: 410 g kg−1) and isoenergetic (gross energy: 18 kJ g−1) diets were formulated. FM was used as the control protein. In the other five diets, 20, 40, 60, 80 and 100% FM protein was substituted with MBM20, MBM40, MBM60, MBM80, MBM100, respectively. Total P content in the diets ranged from 16.0 to 28.3 g kg−1 and the available P was 5.0–6.6 g kg−1. The results showed that the best growth was achieved with fish fed on the control diet and MBM20. Final body weight, weight gain, feed efficiency, protein retention efficiency and energy retention efficiency decreased with increased dietary MBM. No significant differences were found in the feeding rate and hepatosomatic index between the groups. Apparent digestibility coefficient (ADC) of dry matter, protein and P decreased with increase in dietary MBM, while there were no significant differences in the ADC of energy. P and N retention decreased linearly while P and N loading increased linearly with the increased dietary MBM levels. No significant differences were observed in the activity of alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase, as well as pyruvate kinase in liver or in serum. Total superoxide dismutase activity in MBM20 was significantly higher than that of MBM100. [ABSTRACT FROM AUTHOR]

The nutritional function of monosaccharides, disaccharides and polysaccharides for omnivorous gibel carp and carnivorous Chinese longsnout catfish were investigated and the ability of these two species to utilize carbohydrates was compared. For each species, triplicate groups of fish were assigned to each of five groups of isoenergetic and isonitrogenous experimental diets with different carbohydrate sources: glucose, sucrose, dextrin, soluble starch (acid-modified starch) and α-cellulose. The carbohydrates were included at 60 g kg−1 in Chinese longsnout catfish diets and at 200 g kg−1 in gibel carp diets. A growth trial was carried out in a recirculation system at 27.8 ± 1.9 °C for 8 weeks. The results showed that fish with different food habits showed difference in the utilization of carbohydrate sources. For gibel carp, better specific growth rate (SGR) and feed efficiency (FE) were observed in fish fed diets containing soluble starch and cellulose, but for Chinese longsnout catfish, better SGR and FE were observed in fish fed diets containing dextrin and sucrose. Apparent digestibility coefficient of dry matter (ADCd) and apparent digestibility coefficient of energy (ADCe) were significantly affected by dietary carbohydrate sources in gibel carp. ADCd and ADCe significantly decreased as dietary carbohydrate complexity increased in Chinese longsnout catfish except that glucose diet had medium ADCd and ADCe. In both species, no significant difference of apparent digestibility coefficient of protein was observed between different carbohydrate sources. Dietary carbohydrate sources significantly affected body composition, and liver phosphoenolpyruvate carboxykinase (PEPCK), pyruvate kinase (PK), glucose 6-phosphate dehydrogenase (G6PD) and malic enzyme (ME) activities also varied according to dietary carbohydrate complexity. Fish with different food habits showed different abilities to synthesize liver glycogen, and the liver glycogen content in gibel carp was significantly higher than in Chinese longsnout catfish. The influence of carbohydrate source on gluconeogenesis and lipogenesis was also different in the two fish species. [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]

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]

A 100-day growth trial was executed to determine the dietary selenium (Se) requirement of juvenile gibel carp ( Carassius auratus gibelio). Selenomethionine was supplemented to casein-gelatin diets at 0, 0.1, 0.25, 0.5, 1.0, 2.5 and 5 mg Se kg, respectively. Each of these seven semi-purified diets containing 0.34, 0.47, 0.66, 0.82, 1.23, 2.77 and 5.13 mg Se kg was fed to triplicate groups of gibel carp (2.74 ± 0.02 g) in a flow-through system. No behaviour abnormalities and no mortality were found in fish exposed to dietary Se concentrations. With the increasing dietary Se supplemented concentrations, weight gain of fish remarkably increased at the levels of ≤1 mg Se kg diet and then showed no significant difference above 1 mg Se kg levels. Although growth performances (weight gain, hepatosomatic index, condition factor and survival) were not impaired in gibel carp fed at above the levels of 2.5 mg Se kg, indicators of oxidative stress were changed significantly. Serum superoxide dismutase (SOD) activities significantly declined, hepatic glutathione peroxidase (GPx) activities significantly increased and the tissue Se concentrations significantly raised at the highest supplemented level of 5 mg Se kg. A clear linear relationship between Se-depended GPx activities and hepatic Se concentrations was observed. The present results indicated that the dietary Se requirement for gibel carp is 1.18 mg Se kg diet based on weight gain, GPx activities and tissue accumulation. [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]

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]

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]