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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 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]

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]

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 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]

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]