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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]

This study investigated the effects of the co-supplementation of vitamins C (0, 500, and 1000 mg kg−1) and E (0, 62.5, and 125 mg kg−1) on the growth performance, haematology and the modulation of blood stress indicators and immune parameters in hybrid catfish ( Clarias macrocephalus × Clarias gariepinus) under combinations of thermal and acidic stress. Supplementation of vitamins C and E influenced the growth, haematological indices, serum chloride, plasma protein and immune parameters (lysozyme, total immunoglobulin and alternative complement haemolytic assay) ( P < 0.05). Although vitamins C and E did not prevent a significant reduction in serum chloride, they minimized not only the modulation of blood glucose and plasma protein, but also the reduction in immune parameters ( P < 0.05) owing to stress. Our results demonstrated that co-supplementation of 500 mg kg−1 vitamin C and 125 mg kg−1 vitamin E, or 1000 mg kg−1 vitamin C alone, for four weeks and co-supplementation of both vitamins at low levels (vitamins C at 500 mg kg−1 and E at 62.5 mg kg−1) for eight weeks had beneficial effects on the growth, amelioration of stress-mediated adverse changes in the physiological and immunosuppressive responses of hybrid catfish under stressful conditions. [ABSTRACT FROM AUTHOR]

A 50-day feeding trial was conducted to determine the effects of dietary oxidized fish oil ( OFO) and vitamin C ( VC) on growth and oxidative stress in juvenile red sea bream. Test diets were formulated with 2 degrees of peroxide value (23 and 29 meq kg−1) combined with 3 levels of VC (0, 400 and 800 ppm). No significant difference was found on growth performance between fish fed OFO with 400 or 800 mg VC and the control group that fed a diet with fresh fish oil after 50 days. However, fish fed OFO without VC supplement indicated significantly poor growth than the control group. Liver and muscle thiobarbituric acid reactive substances were reduced by increased VC intake of fish. Fish fed diets containing low OFO with 400 and 800 mg VC, high OFO with 800 mg VC, and fresh fish oil are allocated in the zone of high resistance against oxidative stress together with low oxidative stress condition. On the other hand, no VC supplemented group was under the highest oxidative stress condition. In conclusion, dietary oxidized lipid increased the oxidative stress condition of fish, but more than 400 mg VC kg−1 of dietary supplement improved growth and health of juvenile red sea bream. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin C on survival and growth of juvenile crayfish ( Pacifastacus leniusculus). An 80-day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets differing in the content of l-ascorbyl-2-monophosphate- Na were prepared: 0, 0.2, 0.4 or 0.8 g kg−1 diet. Each diet was tested on grouped or individually isolated crayfish. Diets had no significant effects on survival of crayfish held in groups (average: 73.1%) neither on the isolated ones (average: 90%). Crayfish fed the diet with 0.2 g kg−1 of l-ascorbyl-2-monophosphate- Na had the highest growth (groups: 13.64 mm carapace length ( CL), 542.4 mg weight; isolated: 17.05 mm CL, 1213.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 0.99). This study provides the first data on vitamin C requirements of freshwater crayfish. A level of 0.2 g l-ascorbyl-2-monophosphate- Na kg−1 diet (0.07 g ascorbic acid equivalent) can be recommended for juvenile P. leniusculus during the first period of intensive rearing. [ABSTRACT FROM AUTHOR]

A 10-week feeding trial was conducted to determine the optimal requirement of cobia ( Rachycentron canadum Linneaus) for dietary ascorbic acid (AA). Graded levels of L-ascorbyl-2-polyphosphate (LAPP) were supplemented in basal diet to formulate six semi-purified diets containing 2.70 (the control diet), 8.47, 28.3, 80.6, 241 and 733 mg AA equivalent kg diet, respectively. Each diet was randomly fed to triplicate groups of fish in flow-through plastic tanks (300 L), and each tank was stocked with 25 fish with average initial weight of 4.59 ± 0.36 g. Observed deficiency signs included poor growth, higher mortality and lower feeding rate (FR) in the fish of the control group. Fish fed the control diet had significantly lower weight gain (WG), lower feed efficiency ratio (FER) and lower tissue AA concentrations in fish liver and muscle. With the increase of dietary AA, the survival, WG, FER, hepatic and muscular AA concentrations of cobia significantly increased and then levelled off. The dietary AA requirement of cobia was estimated to be 44.7 mg kg based on WG, 53.9 mg kg or 104 mg kg based on either hepatic or muscular AA concentration, respectively. [ABSTRACT FROM AUTHOR]

This study was conducted to examine the effects of dietary ascorbic acid (AsA) and phospholipid (PL) and their interaction on growth, survival, and stress resistance in red sea bream larvae. Twenty-six days old red sea bream were fed nine micro-bound diets supplemented three levels of AsA (0, 800 and 1600 mg kg−1 diet) and PL (0, 20 and 40 g kg−1 diet) for 15 days. Dietary AsA and PL were both significant factors on survival rates. There was also an interaction between dietary AsA and PL on survival rate ( P < 0.05). The larvae fed 800 or 1600 mg kg−1 AsA with 40 g kg−1 PL diets showed the highest survival rate, with values similar to those of the live-food supplemented group. Stress resistance against low salinity exposure significantly increased with increased dietary level of AsA and PL. However, significant interaction of AsA and PL was not detected. The larvae fed 1600 mg kg−1 AsA with 40 g kg−1 PL diet showed the highest stress resistance among all diets, but it was not significantly different than that of larvae fed 800 mg kg−1 AsA with 40 g kg−1 PL diet. This study clearly demonstrated that combined use of AsA and PL can improve survival of 26–40 days posthatching red sea bream larvae. Moreover, the present study suggested that 800 mg kg−1 AsA with 40 g kg−1 PL in diet was needed for producing high quality seedling under the stressful conditions. [ABSTRACT FROM AUTHOR]

l-ascorbyl-2-polyphosphate (ApP) was used as a vitamin C source to investigate the ascorbic acid (AsA) requirements on growth performance and stress resistance of the larval white shrimp, Litopenaeus vannamei. Five isoenergetic and isonitrogenous fish meal-fish protein hydrolysate-based diets with five levels of ApP, AsA equivalent to 91.8, 188, 271, 360 and 436 mg kg−1 diet were fed to triplicate groups of L. vannamei (mean initial wet weight 1 mg) for 32 days. The diet with AsA 91.8 mg kg−1 showed high cumulative mortality after 10 days of feeding. After the 32-day trial, the shrimp that fed the diet had significantly lower survival and weight gain (WG, %) than those that fed 188, 271, 360 and 436 mg AsA kg−1 diets. Specific growth rate (SGR, % day−1) and final body wet weight (FBW, mg) showed the same pattern as WG (%). There were no significant differences in growth performance (FBW, WG and SGR) among the groups that fed 188, 271, 360 and 436 mg kg−1 of AsA at the termination of feeding trial. Broken-line regression analysis on WG indicated that 191 mg AsA kg−1 in the diet was the optimum for larval L. vannamei. On the contrary, dietary level of more than 360 mg AsA kg−1 was needed to ensure high resistance to stressful conditions such as low dissolved oxygen stressors. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to examine the efficacy of a vitamin C (L-ascorbic acid, AsA) derivative,l-ascorbyl-2-monophosphate Na/Ca (AMP-Na/Ca) by comparing tol-ascorbyl-2-monophosphate-Mg (AMP-Mg) in terms of growth, AsA content in tissues, and hematology in yellowtail Seriola quinqueradiata juvenile (1.10 ± 0.01 g). Furthermore, a stress resistance test for the species fed AMP-Na/Ca was also conducted. In experiment 1, 11 test pellet diets with different levels of AMP-Na/Ca (0, 12, 43, 88, 440 and 881 mg AsA kg−1diet) and AMP-Mg (0, 16, 52, 106, 595 and 1164 mg AsA kg−1 diet) were formulated and fed to the yellowtail three times per day for 50 days. In both the vitamin C sources, the survival rates of the fish fed diets without supplemental AsA were lower than 50% at day 20, and more than 50% mortality occurred in fish that fed the diets containing 12 or 16 mg AsA kg−1 after day 30. However, no significant differences were detected in survival and growth among fish that fed the diets containing more than 43 mg AsA kg−1. Liver and brain AsA concentrations generally increased with increasing dietary AsA level in both sources. In experiment 2, test diets were formulated to contain 43, 88, 440 and 881 mg AsA kg−1 using AMP-Na/Ca, and after 60 days of feeding, yellowtail juveniles were subjected to low salinity and air exposure stress. The fish that received diets with 440 mg AsA kg−1 showed significantly higher tolerance to low salinity stress and higher survival rate in air exposure stress than those of other groups. The present study demonstrated that yellowtail juveniles could utilize AMP-Na/Ca as an AsA source like AMP-Mg, and that supplementation of 43–52 mg AsA kg−1 diet was optimum for normal growth. However, this study showed that dietary inclusion of 440 mg AsA kg−1 would be necessary to improve stress resistance of this species. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA)-enriched Artemia in alginate pellets and unenriched pellets were fed to Jasus edwardsii broodstock to supplement AA intake of the basal diet (mussels, squid and compound prawn pellets) during ovarian development before egg extrusion. Pellet AA content ranged from 150 μg g−1 (unenriched) to 9153 μg g−1 (enriched). The basal diet (150 μg AA g−1) was compared with low (150 μg AA g−1), medium (450 μg AA g−1) and high (1350 μg AA g−1) AA supplementation. Dietary AA content was obtained using combinations of unenriched and AA-enriched Artemia in combination with the basal diet. Supplementation resulted in ovarian AA saturation at ∼240 μg g−1, a significant increase over 152 μg g−1 at time 0. Digestive gland concentrations were 76–92 μg AA g−1 for diets containing ≤450 μg AA g−1, but reached 270 μg AA g−1 for the high supplement. The considerable AA store in tail muscle appeared to be translocated to the ovary during maturation. There was no significant AA depletion in eggs during embryogenesis suggesting minimal AA utilization during this phase. Jasus edwardsii spawns once annually, unlike other multiple spawning crustaceans. Therefore, AA supplementation did not alter fecundity or phyllosoma quality, but resulted in a dose-dependent increase (up to 33%) in AA content of eggs and phyllosoma. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to evaluate the efficacy of dietaryl-ascorbic acid (AA) dosages on immunity, growth and survival of the fingerlings of Labeo rohita. AA was supplemented at 0, 100, 200 and 500 mg kg−1 basal diets. Each diet was fed for 8 weeks to duplicate groups of fingerlings of rohu with initial body weight of 35 ± 5 g. Selected biochemical and haematological analyses were evaluated every second week. At the end of the feeding trial of 56 days, fish were divided into two subgroups under each major treatment group for challenge with two pathogens, Aeromonas hydrophila and Edwardsiella tarda. The mortality (%) and agglutinating antibody titre were recorded on 28th day postchallenge. Non-specific immune parameters like superoxide anion production, lysozyme activity and complement activity increased independently of the levels of AA in the diet. Whereas phagocytic ratio, phagocytic indices, lymphokine production indices and serum bactericidal activity were better in the group of fish fed with 200 mg AA kg−1 feed for 42 days. However, growth parameters such as specific growth rate, feed conversion ratio and survival were better in the group of fish fed with the highest level of AA through feed for 56 days. These data indicated that elevated levels of dietary AA could be recommended for optimum immunity, growth and survival of fingerlings of L. rohita. [ABSTRACT FROM AUTHOR]

The effects of supplementall-ascorbyl-2-polyphosphate (APP) in enriched live food ( Artemia) on reactive oxygen intermediate (ROI) and free radical scavenging enzyme (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione transferase) activities in the muscle of Penaeus vannamei of two sizes exposed to ambient ammonia-N, were investigated. Significantly, decreased ROI value was found in prawns fed on enriched Artemia compared with those fed on starved Artemia ( P < 0.05); the decrease was 24% and 36%, respectively. In both size classes, the antioxidant enzyme activities in prawns fed on enriched Artemia were higher than in those fed on starved Artemia ( P < 0.05). The results demonstrated that the supplementation of ascorbic acid in enriched live food ( Artemia) enhanced the antioxidant capacity of prawn, increasing its defense system that may fight against environmental stress, leading to impaired ammonia toxicity. [ABSTRACT FROM AUTHOR]

To investigate dietary ascorbic acid (AA) requirement of juvenile ayu ( Plecoglossus altivelis) weighing 1.27 ± 0.02 g, eight diets were formulated with graded levels (0, 20, 40, 80, 160, 320, 640 and 1280 mg AA kg−1) of AA supplied as ascorbyl polyphosphate. Each experimental diet was fed to four-replicate groups to apparent satiation three times a day for 8 weeks. At the end of the feeding trial, fish fed AA-deficient diet showed visible AA deficiency signs and low survival. Based on the four-parameter saturation kinetics model, the calculated AA requirement levels for each dose-dependent response [weight gain, hepatic AA concentration, hydroxyproline (HyPro) concentration in skin and HyPro concentration in backbone] were 116, 226, 47 and 35 mg kg−1, respectively. Based on the maximal growth performance, a level of 116 mg AA kg−1 was recommended for commercial diet of juvenile ayu. To maintain tissue HyPro saturation and avoid AA deficiency symptoms, the minimum required dietary AA level was 47 mg kg−1. Hepatic AA saturation was considered as the most stringent criterion for determination of AA requirement. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to determine two vitamin C derivatives,l-ascorbyl-2-sulphate (C2S) andl-ascorbyl-2-polyphosphate (C2PP), to satisfy vitamin C requirement and to test their effects on the non-specific humoral immune responses of juvenile grouper,Epinephelus malabaricus. C2S and C2PP were each supplemented at 20, 50, 80, 150, 250 and 400 mg kg−1 diet in the semi-purified basal diet providing of 7, 16, 28, 55, 86, 142 mg ascorbic acid (AA) equivalent of C2S kg−1 diet and 4, 9, 15, 31, 49, 75 mg AA equivalent of C2PP kg−1 diet, respectively. Basal diet without AA supplemented was included as a control. Each diet was fed to triplicate groups of grouper (mean initial weight: 6.69 ± 0.07 g). Fish fed diets with≥28 mg AA equivalent of C2S or≥4 mg AA equivalent of C2PP kg−1 had significantly (P < 0.05) greater weight gain (WG) than fish fed the unsupplemented control diet. Liver AA concentrations were higher in fish fed diets with≥16 mg AA equivalent of C2S or≥9 mg AA equivalent of C2PP kg−1 than fish fed the control diet. Alternative pathway of complement activation (ACP) was higher in fish fed diets with≥55 mg AA equivalent of C2S or≥15 mg AA equivalent of C2PP kg−1 than fish fed the control diet. Lysozyme activity was higher in fish fed≥86 mg AA equivalent of C2S or≥15 mg AA equivalent of C2PP kg−1 than fish fed the control diet. Analysis by broken-line regression of WG indicated that the adequate dietary vitamin C concentration from each vitamin C derivative in growing grouper is 46.2 mg AA equivalent of C2S kg−1 diet and 17.8 mg AA equivalent of C2PP kg−1 diet, and it also indicated that C2S is approximately 39% as effective as C2PP in meeting the vitamin C requirement for grouper. The data suggest that both C2S and C2PP supplementation support non-specific immune responses of grouper. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the effect of dietary supplementation of vitamin C on anti-acid stress ability in juvenile soft-shelled turtle. The soft-shelled turtles were fed vitamin C supplemented diets at levels of 0, 250, 500, 2500, 5000 and 10 000 mg kg−1 for 4 weeks. The results showed that the phagocytic rate of blood cell in the group fed vitamin C deficient diets, the serum bacteriolytic activity in the two groups fed vitamin C supplemented diet at 0 and 250 mg kg−1 and the serum bactericidal activity in all groups after acid stress significantly decreased compared with those of before stress (P < 0.1). The phagocytic rate of blood cells in the two groups fed vitamin C supplemented diet at 2500 and 5000 mg kg−1 were significantly higher than those of the four groups fed at 0, 250, 500 and 10 000 mg kg−1 (P < 0.01). The serum bacteriolytic activity in the groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg−1 were significantly higher than that of the group fed vitamin C deficient diets (P < 0.05), and the two groups fed vitamin C at 2500 and 5000 mg kg−1 were significantly higher than those of the groups fed at 250 and 10 000 mg kg−1 (P < 0.05). The serum bactericidal activities in the four groups fed vitamin C supplemented diet at 500, 2500, 5000 and 10 000 mg kg−1 were significantly higher than those of the two groups fed at 0 and 250 mg kg−1 diet (P < 0.01), and the two groups fed vitamin C at 2500 and 5000 mg kg−1 were significantly higher than those of the two groups fed at 500 and 10 000 mg kg−1 (P < 0.1). These results suggest that supplementation of vitamin C higher than 250 mg kg−1 is necessary to reduce the adverse effects of acid stress. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to evaluate two vitamin C derivatives, L-ascorbyl-2-monophosphate-Mg (C2MP-Mg) and L-ascorbyl-2-monophosphate-Na (C2MP-Na), to satisfy the vitamin C requirement and to test their effects on the immune responses of juvenile grouper,Epinephelus malabaricus. C2MP-Mg and C2MP-Na were each supplemented at 20, 50, 80, 150, 250, and 400 mg kg−1 diet in the basal diet providing of 7, 18, 31, 51, 93, 145 mg ascorbic acid (AA) equivalent of C2MP-Mg kg−1 diet and 4, 10, 17, 31, 47, 77 mg ascorbic acid (AA) equivalent of C2MP-Na kg−1 diet, respectively. Basal diet without AA supplementation was included as control. Each diet was fed to triplicate groups of grouper (mean initial weight 3.20 ± 0.05 g). Fish fed diets supplemented with either C2MP-Mg or C2MP-Na had significantly (P < 0.05) greater weight gain (WG), feed efficiency and survival than those fed the unsupplemented control diet. Liver ascorbate concentrations in fish generally increased as dietary C2MP-Mg or C2MP-Na supplementation level increased. Haemolytic complement activity was higher in fish fed diets supplemented with 92 mg AA equivalent of C2MP-Mg kg−1 or 10–17 mg AA equivalent of C2MP-Na kg−1 than fish fed the unsupplemented control diet. Lysozyme activity was higher in fish fed≥51 mg AA equivalent of C2MP-Mg kg−1 or≥47 mg AA equivalent of C2MP-Na kg−1 than fish fed the unsupplemented control diet. Analysis by broken-line regression of WG indicated that the adequate dietary vitamin C concentration from each vitamin C derivative in growing grouper is 17.9 mg AA equivalent of 2MP-Mg kg−1 and 8.3 mg AA equivalent of C2MP-Na kg−1, and it also indicated that C2MP-Mg is about 46% as effective as C2MP-Na in meeting the vitamin C requirement of grouper. [ABSTRACT FROM AUTHOR]

Newly hatched Jasus edwardsii phyllosoma were fed unenriched Artemia [endogenous ascorbic acid (AA) concentration of 166 μg g−1 dry weight (dw)], Artemia supplemented with algae (AA concentration 594 μg g−1 dw) or with ascorbyl-2-polyphosphate (A2P) (AA concentration 11 737 μg g−1 dw) to examine possible benefits of AA enhancement on culture. Plain or algal-enriched Artemia were fed continuously for 28 days in two treatments during the study. Four other treatments received A2P-enriched Artemia on a progressive basis starting from the commencement of the trial (D-0), the third (D-3), sixth (D-6) or ninth day (D-9) of Stage I (14 days) and similarly during Stage II (14 days). Prior to the commencement of A2P supplementation, plain Artemia were supplied to these animals. By Stage III (28 days feeding), algal, D-0 and D-3 phyllosoma had attained the largest size. The uptake and retention of AA by Stage III phyllosoma appeared to be dose-dependent with the highest concentration of AA incorporation evident in D-0 phyllosoma (1816 μg g−1 dw), while algal and plain phyllosoma contained the lowest concentrations (600 and 300 μg g−1 dw, respectively). Survival at Stage III was highest in D-0 phyllosoma (89%) and lowest in plain phyllosoma (51%). There was a positive relationship between phyllosoma AA concentration and larval survival ( R2 = 0.8328, P < 0.0001). D-0 phyllosoma had the lowest stress index when subjected to an osmotic/temperature activity test, indicative of better survival in culture compared to plain, algal and D-9 phyllosoma, which had consistently higher indices. A negative relationship existed between phyllosoma AA concentration and stress indices at Stage III ( R2 = 0.9263, P < 0.0001), suggesting that AA from the Artemia diet conferred stress resistance. [ABSTRACT FROM AUTHOR]

A study was conducted to establish whether a particulate form of ascorbic acid (AA), ascorbyl-2-phosphate (A2P), could be used to enrich Artemia. In the first experiment, we examined the efficiency of A2P conversion to and maintenance of AA by juvenile Artemia (1.5 mm, 5-day-old) held at 9000 L−1 and 28 °C for 24 h. Maximal uptake and assimilation was >10 000 μg AA g−1 dry weight (dw) (representing >1% Artemia dw) at enrichment rates of ≥1.2 g A2P L−1. In the second experiment, a similar biomass of instar II/III nauplii (1 mm, 2-day-old) and juvenile (2.5 mm, 8-day-old) Artemia were enriched for 6 or 24 h at 28 °C before starvation for 6 or 24 h at 18 or 28 °C. At 0 h and after 6 and 24 h enrichment, AA levels were 485, 3468 and 11 080 μg g−1 dw in nauplii and 122, 4286 and 12 470 μg g−1 dw in juveniles. When Artemia nauplii or juveniles were enriched for 6 h and starved for 6 h at 18 or 28 °C, there was no significant reduction in AA. Continuation of starvation to 24 h at 18 and 28 °C reduced the level of AA to 3367 and 2482 μg g−1 dw in nauplii and 3068 and 2286 μg g−1 dw in juveniles. After 24 h enrichment, 6 h of starvation at 18 and 28 °C reduced AA to 8847 and 7899 μg g−1 dw in nauplii and to 9053 and 8199 μg g−1 dw in juveniles. Continuation of starvation to 24 h at 18 and 28 °C further reduced AA levels in nauplii to 6977 and 4078 μg g−1 dw and to 7583 and 5114 μg g−1 dw in juveniles. This study demonstrated that A2P could be assimilated as AA in the body tissue of different-sized Artemia in a dose-dependant manner and AA was depleted during starvation depending on time and temperature. [ABSTRACT FROM AUTHOR]

Abstract Fish fillet quality has been shown to be influenced by the level of antioxidants in preslaughter diet. Thus, an experiment was conducted to study the effect of different levels of vitamin E and C on the fillet quality of market-size reared turbot (Scophthalmus maximus ). Turbot of a mean initial weight of 347 ± 20 g were divided into four groups and fed commercial turbot diets (60% protein, 12% fat), supplemented with α -tocopheryl acetate (mg kg -1 ) and ascorbyl-2 monophosphate (mg kg -1 ) at the following dietary levels: 500/100, 1000/100, 100/1000, 100/100 respectively. Over a dietary supplementation period of 15 weeks, fish were fed to satiation and reached a final mean weight of 916 ± 29 g. α-Tocopherol levels increased significantly ( P < 0.001) in tissue (i.e. muscle, liver, heart and kidney) of fish fed diets containing elevated levels of α -tocopheryl acetate. In ice storage, fillets of these fish exhibited significantly lower ( P < 0.001) levels of lipid oxidation, and showed significantly less ( P < 0.001) colour deterioration (higher hue angle and lower chroma). Elevated dietary α -tocopheryl acetate levels had a negative effect ( P ≤ 0.001) on the concentration of ascorbic acid in muscle tissue. An increase in dietary vitamin C did not have any detectable effect on fillet quality. Prolonged feeding times had a negative effect on lipid oxidation ( P < 0.001) and colour deterioration ( P < 0.01). These results suggest that increased dietary α -tocopheryl acetate could prevent colour deterioration and lipid oxidation of turbot fillets in retail storage on ice. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of enriching Artemia nauplii with vitamin C (ascorbyl-6 palmitate) or vitamin E (α-tocopherol acetate), 20% w/w, together with a mixture of concentrated eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) on the growth, survival, and stress resistance of fresh water walleye Stizostedion vitreum larvae. Either cod liver oil (CLO) or EPA/DHA ethyl esters concentrate was used as lipid sources in the Artemia enrichment. Walleye larvae were fed ad libitum for 40 days. At day 40, submersion in salt water (25 g L-1) was performed to evaluate larvae resistance to stress. EPA and DHA levels in walleye juveniles fed EPA/DHA-enriched Artemia increased significantly, by an average of 650% compared with fish fed non-enriched Artemia. A significant increase was found for vitamins C (71.8 ± 1.0 and 42.7 ± 1.2 μg g-1 wet weight (WW)) and E (17.0 ± 3.7 and 6.5 ± 0.9 μg g-1WW) concentrations in fish fed enriched and unenriched Artemia, respectively. Growth was comparable throughout treatments, whereas survival was significantly higher in fish fed CLO-enriched Artemia nauplii compared with fish fed Artemia nauplii enriched with EPA/DHA concentrate. The addition of vitamin C increased fish survival by 1.4-fold compared with fish fed Artemia enriched with only EPA/DHA concentrate. The survival of the latter was similar to control fish (Artemia without enrichment). The supplementation of vitamin E did not affect fish survival significantly. Stress tests revealed that the resistance of walleye larvae to salinity changes increased when Artemia enrichment was supplemented with vitamin C. However, walleye larvae fed CLO-enriched Artemia had the best performances in the stress test. [ABSTRACT FROM AUTHOR]

A culture trial was performed using five levels of ascorbic acid 2-monophosphate (AmP at 0, 10, 100, 1000 and 2000 mg kg-1 diet, expressed as active ascorbic acid, AA) in a semipurified diet for early postlarval Penaeus vannamei. The experiment started 10 days after metamorphosis of the mysid larvae into postlarvae (=PL10). Each treatment was run in four replicates. P. vannamei postlarvae showed significantly better growth according to dietary AA level after 25 days of feeding, i.e. at PL36 stage. Whereas the dry weight of PL36 in the control treatment (0 mg AA kg-1 diet) was only 2 mg, supplementation of 1000 mg AA kg-1 increased the shrimp dry weight up to 18 mg. However, the growth in the other treatments was not significantly different from the control. Fitting a broken-line regression to the biomass yield demonstrated an optimal dietary level of 130 mg AA kg-1 diet. There were no differences observed among the treatments in stress resistance of postlarval P. vannamei to a salinity shock. [ABSTRACT FROM AUTHOR]

The enrichment and retention of ascorbic acid (AA) was investigated in rotifers Brachionus plicatilis fed on microalgae (Nannochloropsis oculata and Isochrysis sp. (T.ISO)) and baker's yeast Saccharomyces cerevisiae. The concentrations of AA of the rotifer diets used in the study differed significantly: 4200 μg g[sup -1] of dry weight in Isochrysis sp. (T.ISO), 2600 μg g[sup -1] in N. oculata and only 77 μg g[sup -1] in S. cerevisiae. Rotifers contained 620 μg AA g[sup -1] prior to the experimental feeding. When subsequently fed for 3 h on microalgae at a ration of 0.13 mg dry microalgae per 10[sup 6] rotifers rapidly and efficiently increased their content of AA: Isochrysis sp.-fed rotifers contained 1600 μg AA g[sup -1] and N. oculata-fed rotifers contained 1100 μg AA g[sup -1]. Concentrations were boosted by a further feeding of a second ration of algae at three times the initial feeding ration; 21 h later, Isochrysis sp.-fed rotifers contained 2500 μg AA g[sup -1] and N. oculata-fed rotifers contained 1700 μg AA g[sup -1]. This represented a 180% and 310% increase in the pre-feeding vitamin concentrations in Isochrysis sp. and N. oculata-fed rotifers, respectively. There were no significant changes in AA concentration in rotifers fed a similar ration of yeast throughout the feeding period (520-620 μg AA g[sup -1]). Rotifers retained AA during a subsequent 24 h non-feeding period, with no significant changes in the concentrations in any of the rotifer groups. The production of rotifers rich in AA may be particularly valuable for the culture of fish larvae that have a high requirement for the vitamin. [ABSTRACT FROM AUTHOR]

Growth, survival, tissue ascorbate concentration and collagen content were studied in fast-growing Penaeus monodon fed two ascorbic acid (AA) derivatives. Prior to the experimental trial, shrimp (initial body weight: 0.9 ± 0.4 g) were fed on a diet lacking vitamin C for 5 weeks. During the following 13-week experiment, the shrimp (initial body weight: 8.2 ± 0.7 g) were given one of five squid-meal-based diets. The dietary treatments consisted of a diet lacking vitamin C, two diets supplemented with either 500 or 1000 mg AA kg[sup -1] in the form of silicone-coated AA, and two diets supplemented with either 500 or 1000 mg AA kg[sup -1] in the form of ascorbyl-2-polyphosphate. Shrimp gained 18.3 g in 13 weeks. The AA-free diet group exhibited the lowest growth rate, feed intake and survival (26.8%) after 4 weeks. Hepatopancreatic ascorbate and muscle collagen content were significantly (P < 0.05) lower in AA-deprived shrimp. At the end of the feeding trial, growth rate and survival were not significantly (P > 0.05) different among groups fed AA-supplemented diets. Hepatopancreatic and haemolymphatic ascorbate concentrations were significantly (P < 0.05) higher in groups given ascorbyl-2-polyphosphate than in groups given silicone-coated AA. A supplement of 500 mg AA kg[sup -1] diet in the form of either silicone-coated AA or ascorbyl-2-polyphosphate was adequate for optimal growth. But ascorbate concentrations in tissues remained much below saturation levels with a supplement of 1000 mg AA kg[sup -1] diet. It is questionable whether the established vitamin C requirements for P. monodon are adequate to maintain tissue ascorbate in fast-growing juveniles. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the minimum dietary vitamin C requirement of juvenile red drum and characterize signs of vitamin C deficiency. Semipurified diets containing 400 g crude protein kg–1 from lyophilized red drum muscle and crystalline amino acids were used in the feeding trial. The basal diet without supplemental vitamin C contained ≈ 6 mg vitamin C kg–1 and was fed for a 1-week conditioning period. Red drum, initially averaging ≈ 3.6 g each, were fed diets supplemented with 0, 10, 20, 30, 45, 60, 75, or 150 mg vitamin C kg–1 as ascorbate polyphosphate for a period of 10 weeks. Fish fed the basal diet began to exhibit overt signs of vitamin C deficiency, including reduced weight gain, lordosis, scoliosis and loss of equilibrium after 8 weeks. Total ascorbate was undetectable in liver of fish fed the basal diet while liver ascorbate levels in fish fed the other diets generally reflected dietary supplementation. Regression analysis of weight gain data using the broken-line model resulted in a minimum vitamin C requirement (±SE) of 15 ± 3 mg kg–1 diet. [ABSTRACT FROM AUTHOR]