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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]