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Vitamin C (VC) plays an essential role in fish physiological function and normal growth. However, its effects and requirement of coho salmon Oncorhynchus kisutch (Walbaum, 1792) are still unknown. Based on the influences on growth, serum biochemical parameters, and antioxidative ability, an assessment of dietary VC requirement for coho salmon postsmolts (183.19 ± 1.91 g) was conducted with a ten-week feeding trial. Seven isonitrogenous (45.66% protein) and isolipidic (10.76% lipid) diets were formulated to include graded VC concentrations of 1.8, 10.9, 50.8, 100.5, 197.3, 293.8, and 586.7 mg/kg, respectively. Results showed that VC markedly improved the growth performance indexes and liver VC concentration, enhanced the hepatic and serum antioxidant activities, and increased the contents of serum alkaline phosphatase (AKP) activity, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and total cholesterol (TC) whereas decreased the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, and triglyceride (TG) level. Polynomial analysis showed that the optimal VC levels in the diet of coho salmon postsmolts were 188.10, 190.68, 224.68, 132.83, 156.57, 170.12, 171.00, 185.50, 142.77, and 93.08 mg/kg on the basis of specific growth rate (SGR), feed conversion ratio (FCR), liver VC concentration, catalase (CAT), hepatic superoxide dismutase (SOD) activities, malondialdehyde (MDA) content, and serum total antioxidative capacity (T-AOC), AKP, AST, and ALT activities, respectively. The dietary VC requirement was in the range of 93.08–224.68 mg/kg for optimum growth performance, serum enzyme activities, and antioxidant capacity of coho salmon postsmolts. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the growth performance and fin regeneration rates of zebrafish fed with diets containing levels of vitamin C (Vit C). A basal practical diet was formulated to test six levels of Vit C supplementation (0, 75, 150, 300, 600 and 1,200 mg kg−1). A total of 504 juvenile zebrafish were distributed into thirty‐six 8‐L aquaria, constituting an experimental design with six treatments and six replicates. After 60 days of feeding, growth performance was evaluated. To analyse the regeneration rates of the caudal fin, 18 fish of each treatment were anesthetized and had part of their fins amputated. To determine the regenerated portion on Days 5, 10 and 15 postamputation, six fish of each treatment were subjected to image analysis. The average weight gain, specific growth rate, feed conversion ratio and final length were positively affected (p <.05) by Vit C supplementation. The diets with higher dietary concentrations of Vit C presented the best results regarding tissue regeneration. Based on the broken‐line regression analysis, it is concluded that the Vit C nutritional requirement for the maximum growth and tissue regeneration of zebrafish juveniles fed with practical diets for 60 days were 188.7 and 897.4 mg kg−1 diet, respectively. [ABSTRACT FROM AUTHOR]

L‐ascorbyl‐2‐monophosphate (AMP) was used as a vitamin C source to investigate its effects on growth performance and nonspecific immunity of red swamp crayfish (Procambarus clarkii). Six experimental diets (AMP0, AMP15, AMP30, AMP45, AMP60 and AMP75) with different levels of AMP (.00, 141.01, 280.44, 419.06, 558.13 and 692.09 mg kg−1 diet, respectively) were fed to juvenile crayfish (average weight:.70 ±.01 g) for 56 days. At the end of the 56‐day trial, the highest final body weight, specific growth rate (SGR), phenoloxidase activity, lysozyme activity, superoxide dismutase activity and anti‐superoxide anion activity all occurred in the AMP30 group (p <.05). Compared with the AMP0 group, crayfish fed with AMP‐supplemented diets showed significantly higher hepatosomatic index value (p <.05). Conversely, the feed conversion ratio value of crayfish fed with AMP‐supplemented diets was significantly reduced relative to that of the AMP0 group (p <.05). AMP15 to AMP30 diets showed significantly higher muscle rate value, crude protein content, total haemocyte count and blood cell respiratory burst activity (p <.05). Broken‐line regression analysis on SGR indicated that the optimal dietary AMP level of red swamp crayfish was estimated to be 300.95 mg kg−1 diet. [ABSTRACT FROM AUTHOR]

Vitamin C or ascorbic acid (ASA) is an essential micronutrient for normal growth, antioxidant capacity and immunity of fish. However, appropriate requirements of ASA for Ctenopharyngodon idella, grass carp juveniles (8.46 ± 0.19), remain unknown. For this purpose, a feeding trial of 60 days was conducted in triplicates. Six isolipidic and isoproteic diets containing 0, 25, 50, 100, 200 and 400 mg/kg of ASA were prepared. Results showed a linear increase in growth as ASA supplementation was increased from 0 to 100 mg/kg. However, a further increase in dietary ASA supplementation from 200 to 400 mg/kg resulted in a slight decrease in growth parameters. A similar trend was also recorded for the whole body, proximate composition, antioxidant enzymes and organ indices against ASA supplementation. On the contrary, fish fed with basal diet had higher thiobarbituric acid reactive substances (TBARS) content in the liver and muscles than those fed with ASA supplemented diets. ASA concentration in muscles increased in a dose‐dependent manner, while ASA value was the highest in the fish fed with 100 mg/kg ASA concentration. The weight gain (WG%) data were subjected to broken‐line regression analysis, and the optimal ASA requirement of grass carp juveniles was estimated to be 67.1667 mg/kg. Taken together, the inclusion of 67.1667 mg/kg of ASA is recommended in the feed of grass carp juveniles for optimum growth performance. We also recommend analysing the effect of ASA in combination with vitamin A and E. [ABSTRACT FROM AUTHOR]

A 14‐week feeding trial was conducted to determine the effects of dietary L‐ascorbyl‐2‐polyphosphate on the growth performance, haematological parameters, biochemical characteristics, and skeletal features of juvenile hybrid grouper (♀Epinephelus fuscoguttatus × ♂E. lanceolatus). Eight experimental diets containing graded vitamin C (VC) levels (0, 18, 45, 78, 144, 245, 386, and 762 mg/kg) were prepared and fed to triplicate groups of fish (initial body weight: 10.41 ± 0.06 g). The final body weight, weight gain rate, specific growth rates, and fish survival increased when fed with diets supplemented with VC regardless of the supplementation level. Total feed intake reduction was observed in fish fed non‐VC diet. Whereas no significant differences were detected in the feed conversion ratios and protein efficiency ratios among fish treatments. The hepatic VC concentration was positively correlated with dietary VC supplementation and reached a plateau when supplemented with more than 386 mg/kg diet. Higher total protein and alkaline phosphatase levels in blood serum and incidence of skeletal deformities were recorded in the fish fed with a control diet compared to other treatments. The results indicate that adding 18 mg/kg of VC is optimum and further increase does not provide any significant benefit to fish growth and health. [ABSTRACT FROM AUTHOR]

An 8‐week feeding experiment was implemented to study the effect of dietary vitamin C (VC) on growth, immunity, oxidation resistance and relevant gene expressions in juvenile S. sihama (2.33 ± 0.02 g). Fish were fed six diets containing VC level of 5, 16, 27, 65, 122 and 233 mg/kg, respectively. VC‐deficient signs including ascites syndrome, skin decay and haemorrhage were found in the fish fed basal diets. Appropriate VC supplement in diets (a) increased weight gain (WG), specific growth rate (SGR), feed intake (FI) and protein efficiency ratio (PER); (b) increased contents of hepatic total immunoglobulin (IgM), complement 3 (C3) and complement 4 (C4) and activity of alkaline phosphatase (AKP); (c) increased hepatic and intestinal copper–zinc superoxide dismutase (CuZnSOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione S‐transferase (GST) activities, but decreased hepatic MDA content; and (d) up‐regulated gene expressions of NF‐E2‐related factor 2 (Nrf2), Kelch‐like ECH‐associated protein 1 (Keap1), CAT, GST, GPx, glutathione reductase (GR), CuZnSOD and manganese superoxide dismutase (MnSOD) in liver and intestine. These results indicated that dietary VC significantly influenced the growth, immunity and oxidation resistance at enzymatic and genic levels. Based on regression analysis for PER, IgM, intestinal CuZnSOD and hepatic VC concentration, the optimal requirement of dietary VC in juvenile S. sihama was estimated to be 98.33, 139.03, 104.23 and 143.69 mg/kg. [ABSTRACT FROM AUTHOR]

Vitamin C is an essential micronutrient for normal physiological and immune functions of fish. However, its requirements and effects in Chu's croaker (Nibea coibor) are currently unknown. A 56‐day feeding trial was conducted to evaluate the optimal dietary vitamin C requirements based on its effects on growth performance, body composition and biochemical parameters in juvenile Chu's croaker (14.17 ± 0.1 g). Six isoproteic (450 g/kg crude protein) and isolipidic (100 g/kg crude lipid) diets were formulated to contain 2.24 (basal diet), 39.03, 85.01, 171.16, 356.49 and 715.46 mg/kg of vitamin C. The results showed that fish fed on 171.16 mg/kg vitamin C diet had the highest growth performance and feed utilization. Fish fed on the basal diet had higher malondialdehyde (MDA) content and lower activities of antioxidant enzymes in the serum and liver as compared with those fed on vitamin C diets. Polynomial analysis indicated that the optimal dietary vitamin C requirements of juvenile Chu's croaker were 102.28, 98.21, 150.26, 165.38, 71.46, 176.19, 84.84 and 103.78 mg/kg based on weight gain, specific growth rate, liver storage, muscle storage, liver MDA content, liver alanine aminotransferase activity, liver alkaline phosphatase activity and liver superoxide dismutase activity, respectively. We recommend an inclusion level in the range of 71.46–150.26 mg/kg vitamin C in the diets of juvenile Chu's croaker for optimum growth performance, liver function, antioxidant capacity and innate immunity functions. [ABSTRACT FROM AUTHOR]

An 80‐day feeding trial was conducted to evaluate the effects of dietary ascorbic acid (AA) supplementation at different levels (0, 0.2 and 0.4 g/kg l‐ascorbate‐2‐polyphosphate; 7.6, 77.2 and 146.7 mg/kg AA, respectively) on cholesterol metabolism in rainbow trout (Oncorhynchus mykiss). Dietary AA supplementation regardless of inclusion level increased the serum total cholesterol and low‐density lipoprotein (LDL) cholesterol levels and LDL cholesterol/high‐density lipoprotein cholesterol ratio. No significant differences were observed in the serum triiodothyronine and thyroxine levels, faecal cholesterol content, hepatic activity and mRNA expression of acyl‐coenzyme A:cholesterol acyltransferase among the dietary treatments. Dietary AA inclusion increased the faecal bile acid content, hepatic activity and mRNA expression of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase and hepatic cholesterol 7α‐hydroxylase mRNA expression, but decreased the hepatic LDL receptor content. High level of AA supplementation (0.4 g/kg) depressed the serum cortisol levels. These results suggest that dietary supplementation with 0.2‒0.4 g/kg l‐ascorbate‐2‐polyphosphate may increase the serum total cholesterol level in rainbow trout. The cholesterol‐raising effect of AA may be due to the increased hepatic cholesterol production and the depressed cholesterol clearance from serum. In addition, dietary AA inclusion also facilitates the hepatic conversion of cholesterol to bile acids. [ABSTRACT FROM AUTHOR]

A 56‐day experiment was carried out to investigate the effects of dietary vitamin C and vitamin E on the growth, antioxidant status and digestive enzyme activities of discus fish (Symphysodon haraldi; initial body weight: 7.96 ± 0.61 g and body length: 5.45 ± 0.65 cm). Animals were fed with 13 different diets including one control diet and 12 treatment diets containing four levels of vitamin C (magnesium‐L‐ascorbyl‐2‐phosphate; 40, 80, 120 and 160 mg/kg) crossed with three levels of vitamin E (DL‐α‐tocopheryl acetate; 40, 80 and 120 mg/kg). The results showed that the fish fed diets containing additional vitamin C (40 mg/kg) and vitamin E (80 mg/kg) showed higher specific growth rate, length growth rate, total antioxidant capacity and protease activity but had lower feed conversion ratio and total superoxide dismutase activity than those fed the control diet. Collectively, these findings suggest that the inclusion of additional 40 mg/kg of vitamin C and 80 mg/kg of vitamin E in the basal diet could have beneficial effect on the growth, antioxidant defence and digestion of S. haraldi. [ABSTRACT FROM AUTHOR]

Abstract: A sixty‐day feeding trial was conducted to determine the ascorbic acid (AA) requirement for growth of striped catfish, Pangasianodon hypophthalmus juveniles. Seven iso‐nitrogenous and iso‐energetic (370 g protein per kg and 19.6 MJ/kg) purified diets were prepared with different levels of ascorbic acid such as control (0), T1 (17.5), T2 (35), T3 (70), T4 (175), T5 (350) and T6 (700) mg ascorbic acid (L‐ascorbyl‐2‐polyphosphate) equivalent per kg diet. Fish with a mean body weight of 3.2–3.4 g were stocked (fifteen fish per tank) in triplicates following a completely randomized design. Each group was fed to satiation twice a day for 60 days. Significant differences were observed in growth, survival, body composition and metabolic enzymes activities with different dietary ascorbic acid levels. Maximum weight gain, specific growth rate (SGR) and protein efficiency ratio (PER) were found in fishes fed with 35 mg AA per kg diet, supported by best feed conversion. Fish fed a diet containing vitamin C had the highest activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) compared to those fed with vitamin C‐depleted diets. In this study, based on using broken‐line regression analysis, the dietary vitamin C requirement for growth of P. hypophthalmus juveniles was estimated to be in the range of 46–76 mg AA per kg, depending on the criterion used, growth and liver storage. Our results will be helpful for the formulation of cost‐effective ascorbic acid incorporated diets for striped catfish, P. hypophthalmus. [ABSTRACT FROM AUTHOR]

A 60-day feeding trial was conducted to determine the effects of copper nanoparticles (Cu- NPs) and vitamin C ( VC) on red sea bream. Besides the control diet (D1), six diets were supplemented with Cu- NPs and VC [0/800 (D2), 0/1,000 (D3), 0/1,200 (D4), 2/800 (D5), 2/1,000 (D6) and 2/1,200 (D7) mg Cu- NPs/ VC per kg]. Cu- NP was a significant factor on final weight ( FBW), weight gain ( WG) and specific growth rate ( SGR), feed intake ( FI), feed ( FER) and protein efficiency ratios ( PER), protein gain ( PG) and protein retention ( PR), body protein and lipid contents, protease ( PA) and bactericidal activities ( BA) and tolerance against stress ( LT50%) ( p < .05). In addition, BA and LT50% were significantly affected by either Cu- NPs or VC ( p < .05). Fish fed Cu- NPs or/and VC-supplemented diets showed higher FBW, WG, SGR, PG, PR, FI, PA, LA and BA values when compared with the control group ( p < .05). FER, PER and body lipid content were significantly enhanced in D4, D5, D6 and D7 groups; meanwhile, body protein and LT50% were significantly enhanced in D5, D6 and D7 groups when compared with D1 group ( p < .05). In conclusion, dietary Cu- NPs or/and VC improved growth and health of red sea bream. [ABSTRACT FROM AUTHOR]

The amelioration effect of balanced diet with supplementation of vitamin C against stress was evaluated in freshwater paddy field fish, Clarias batrachus, exposed to organophosphate insecticide, monocrotophos ( MCP). Three groups of fishes, that is, ( E0) Control, ( E1) MCP (2.14 mg L−1) exposure and E2) Vitamin C, MCP (0.2 g kg−1 body weight + 2.144 mg L−1) were selected for the sublethal study. The effect of MCP on protein metabolism in physiological sensitive tissues, namely gills, kidney, liver and muscle of the fish has been determined. Stress on Clarias batrachus was evident that the total protein, amino acid and ammonia contents were decreased, and urea and glutamine levels were elevated in all tissues for 30 days. Similarly, the activities of protease, aminotransferases and phosphatases were elevated significantly in all the tissues during the same period. Fish fed with a diet supplemented by vitamin C (0.2 g kg−1 body weight) could significantly counter these effects. [ABSTRACT FROM AUTHOR]