A multivariate study on the effects of dietary vitamin K, vitamin D3 and calcium, and dissolved carbon dioxide on growth, bone minerals, vitamin status and health performance in smolting Atlantic salmon Salmo salar L.

Bone deformities represent an increasing, unsolved problem for intensive farming of Atlantic salmon, Salmo salar L. To increase insight into nutritional and environmental impacts on bone mineralization, 16 groups of Atlantic salmon parr were fed diets with different levels of menadione sodium bisulphite (MSB), vitamin D₃, and calcium (Ca), and exposed to different levels of dissolved carbon dioxide (CO₂) based on a multivariate factorial design (2⁴). The composition of the experimental diets was either a high or low level of each of the design variables. In addition, four groups (centre points) were fed a diet with intermediate levels of all dietary parameters and exposed to an intermediate level of dissolved CO₂ to record the variation among tanks. After 6 weeks in fresh water, fish were marked according to group, transferred to a common net pen in sea water and fed commercial feed for another 11 weeks. High levels of CO₂ decreased fish growth both in fresh water and sea water. No visible bone deformities were recorded at any time. Dry matter, protein and ash compositions of bone and concentrations of Ca, phosphorus (P) and magnesium (Mg) in bone were not significantly affected by any of the design variables. Minor effects were observed in clinical parameters recording health performance, stress and plasma Ca homeostasis. The mean level of vitamin D₃ measured as cholecalciferol in fish organs increased significantly during the freshwater period and reflected dietary vitamin D₃, whereas the level decreased when fish were fed commercial feed in sea water. The level of menaquinone in liver increased significantly in response to high dietary levels of MSB, indicating that dietary MSB was converted to menaquinone in salmon.     

Vitamin B6 supplementation increases the docosahexaenoic acid concentration of muscle lipids of rainbow trout (Oncorhynchus mykiss)

Fish fillet quality is influenced by feed quality. In particular, vitamin B₆ availability improves growth rate and nutritional value, because it is related to protein and lipid metabolism. The present study investigates the effect of increasing amounts of vitamin B₆ on growth, fatty acid composition and lipid peroxidation of muscle tissue of rainbow trout (Oncorhynchus mykiss). Quadruplicate groups of trout of a mean initial weight of 110 g were fed commercial diets supplemented with four different quantities of vitamin B₆ (0, 10, 25 and 50 mg kg^?1 diet). Over the experimental period, there were no significant differences in weight gain and feed intake, while vitamin B₆ concentration of muscle was affected by dietary intake, even though its increase was not proportional to the concentrations in the feed. The fatty acid composition of muscle lipid showed differences between the four groups. The percentage of long‐chain unsaturated fatty acids, in particular docosahexaenoic acid, increased significantly in vitamin B₆‐supplemented groups. However, despite the increased fatty acid unsaturation index, lipid peroxidation parameters such as vitamin E content, malondialdehyde production, glutathione reductase and glutathione peroxidase activities did not show significant differences, meaning that the higher level of long‐chain unsaturated fatty acid did not increase the muscle susceptibility to oxidative stress.     

Toxicity of Moniliformin and Fumonisin B1 Fed Singly and in Combination in Diets for Young Channel Catfish Ictalurus punctatus

Abstract.— Growth, histological lesions, and biochemical changes were investigated in channel catfish Ictalurus punctatus fed various concentrations of moniliformin with or without fumonisin B₁. Channel catfish (average initial weight, 1.5 g) were fed diets formulated to contain 0, 20, 40, 60, and 120 mg moniliformin/kg; 0, 20, and 40 mg fumonisin B₁/kg, or two combinations of moniliformin and fumonisin B₁ for 10 wk. Fish fed diets with the lowest concentration of moniliformin or fumonisin B₁ (20 mg/kg diet) had significantly (P < 0.05) less weight gain than the control fish. Increasing the level of moniliformin in the diets resulted in a linear decrease in weight gain. Overall mortality of fish was 4% and not related to treatment effects. Hematocrit was significantly (P < 0.05) lowered by 60‐mg moniliformin/kg diet or 40‐mg fumonisin B₁/kg diet. Dose‐dependent increases in serum pyruvate concentration and ratio of free sphinganine to free sphingonine were obtained with increasing concentration of dietary moniliformin and fumonisin B₁, respectively. Mean serum pyruvate level was significantly (P < 0.05) higher in fish fed the diet containing 60‐mg moniliformin/kg diet. Addition of fumonisin B₁ (40 mg/kg) to the diet containing 40‐mg moniliformin/kg significantly increased the serum pyruvate level above that of the control. Also, the lowest concentration of fumonisin B₁ (20 mg/kg diet) significantly (P < 0.05) increased the ratio of sphingolipids. Combinations of moniliformin and fumonisin B₁ at levels of 20:40 and 40:40 mg/kg diet did not significantly change the effect of fumonisin B₁ on the ratio of sphingolipids. The only tissue lesions observed in liver and heart were smaller nuclei of cells in livers of fish fed diets containing the two highest levels of moniliformin and the combinations of the two toxins.     

Influence of dietary menadione nicotinamide bisulphite (vitamin K3) and phylloquinone (vitamin K1) on Atlantic salmon (Salmo salar L.) tissue levels,determined by high‐performance liquid chromatography with fluorescence detection

The aim of the present study was to investigate the retention of menadione nicotinamide bisulphite (MNB; vitamin K₃) and phylloquinone (vitamin K₁) in Atlantic salmon (Salmo salar L.). Another objective was to find a reliable method for determination of menadione in fish feed, and to include and validate more matrices in the methods for phylloquinone and menaquinones (vitamin K₂). Duplicate tanks of Atlantic salmon (～93 g) were fed four levels (0–1000 mg menadione kg^?1 feed) of MNB for 9 weeks. The concentration of menadione and phylloquinone in the feed and the concentration of phylloquinone and menaquinone‐4 (MK‐4) in the tissues were determined. The analysed concentration of dietary menadione found in feed indicated a substantial loss of MNB during feed production. This assumption was supported by screening 15 commercial fish feed samples which also revealed menadione concentrations far below the recommended level. MNB fed salmon showed only a minor increase in liver MK‐4 concentration, compared to salmon fed phylloquinone which had a considerably higher level of liver phylloquinone, indicating a higher retention of phylloquinone compared to menadione in Atlantic salmon. Due to highly varying stability and bioavailability of the different vitamin K derivatives, vitamin K supplementation in fish feed needs a revision.     

Ascorbate-2-sulfate as a dietary vitamin C source for atlantic salmon (Salmo salar): 1. Growth,bioactivity, haematology and humoral immune response

The present experiment shows that ascorbate-2-sulfate (AS) is not equivalent to ascorbic acid (AA) as a dietary vitamin C source for Atlantic salmon (Salmo salar). Within reasonable feed supplemental levels AS does not provide the tissues with adequate supplies of vitamin C to secure optimal physiological functions as demonstrated by biochemical and haematological analyses. AS could not be detected in the liver of fish fed either AA or AS, nor in vitamin C — deprived salmon, suggesting that AS is not the natural storage form of vitamin C in this species. There were no significant differences in antibody production against a soluble artificial antigen (NIP₁₁-LPH) in fish fed 500 and 5000 mg AA/Kg dry diet or equivalent amounts of AS during a period of six weeks at a water temperature of 7.2°C.     

Dietary vitamin C,immunity and disease resistance in Atlantic salmon (Salmo salar)

Presmolt Atlantic salmon were fed a fish meal based experimental diet supplemented with graded levels of ascorbate-2-monophosphate (AP), equivalent to 40, 400, 2000 and 4000 mg ascorbic acid (AA)/kg for 6 months prior to a bacterial challenge experiment. The liver AA concentration reflected the dietary intake of AP, but not linearly. Growth, hematology and acid phosphatase activity in zymosan stimulated macrophages were not affected by dietary AP. Serum hemolytic complement activity was higher in fish fed the highest AP level, but the variation was not significant. Production of specific antibodies was significantly higher in fish fed the highest AP level 11 and 17 weeks after vaccination. Bacterial challenge with Aeromonas salmonicida showed increased survival in the 4000 AP group. Lysozyme activity in headkidney and serum complement activity and serum iron in fish surviving the challenge were higher in the 4000 AP group, indicating important roles of vitamin C on lysozyme, complement and iron in non-specific disease resistance. The results indicate that high dietary levels of AP favourably affect health in Atlantic salmon. Disease resistance was, however, not correlated with the AA status in the liver.     

Dietary menadione nicotinamide bisulphite (vitamin K3) does not affect growth or bone health in first-feeding fry of Atlantic salmon (Salmo salar L.)

The aim of the present study was to elucidate if increasing levels of added vitamin K in the feed influenced fish growth, health or the incidences of bone deformities in Atlantic salmon ( Salmo salar L.) from onset of start feeding to ∼100 g in freshwater. Duplicate groups of Atlantic salmon fry (∼0.20 g) were fed eight levels (0, 2.5, 5, 7.5, 10, 15, 20 and 50 mg menadione kg⁻¹) of the vitamin K derivate menadione nicotinamide bisulphite (MNB) in a regression design for 28 weeks. All fish maintained high growth rates throughout the experiment, and showed no significant differences in specific growth rate, condition factor, whole body proximate analysis, blood coagulation time, vertebra morphology or mechanical properties of vertebrae. We found a dose-response between whole body vitamin K concentration and the dietary MNB supplementation level. Analysis of liver γ-glutamylcarboxylase activity revealed significant dose-dependent differences between groups given the 0, 10 and 50 mg MNB kg⁻¹ diets. In conclusion, Atlantic salmon seems to require low levels of dietary vitamin K, and the amount of vitamin K found naturally in the presently used feed ingredients may be enough to maintain optimal growth, health and bone strength in Atlantic salmon fry from start feeding.     

仿刺参幼参对饲料中维生素B6需求量的研究

为研究仿刺参幼参对维生素B_6的最适需求量,配制维生素B_6实测含量分别为1.23、5.29、9.35、17.47、33.71和66.17 mg/kg的6组实验饲料D1、D2、D3、D4、D5和D6组,饲喂初始体质量为(12.23±0.11) g的仿刺参幼参12周。结果显示,①随着维生素B_6含量的增加,实验仿刺参的增重率、特定生长率均先升后降,在D5组达到最高值;体壁粗蛋白含量先升后降,D6组显著低于其他组;D1组粗脂肪含量显著低于其他组;②体腔液中葡萄糖-6-磷酸脱氢酶、异柠檬酸脱氢酶、乙酰辅酶A羧化酶及一氧化氮合酶活性均先升后降,D6组显著低于其他组;③随着饲料中维生素B_6含量的增加,肠道蛋白酶及淀粉酶活性显著升高,纤维素酶活性显著降低,肠壁厚度及绒毛长度均显著升高。以增重率为评价指标,经一元二次回归分析得出仿刺参幼参饲料中维生素B_6的适宜需求量为45 mg/kg。     

Atlantic salmon fed a nutrient package of surplus methionine,vitamin B12, folic acid and vitamin B6 improved growth and reduced the relative liver size,but when in excess growth reduced

Feeding plant‐based diet through smoltification of Atlantic salmon requires verification of the optimal level of 1C nutrients. Here, we fed Atlantic salmon plant‐based diets containing three different surplus amounts of the 1C nutrients; methionine, cobalamin (vitamin B12), pyridoxine (vitamin B6) and folic acid during 6 weeks in fresh water, through smoltification, followed by 3 months on‐growing period in salt water. The three diets were fed to fish dispersed in triplicate tanks throughout the experiment. Mean start body weight was 32 g. Dietary methionine levels in the diets were 6.7, 9.2 and 11.7 g/kg. Dietary B6 was 6.75, 8.45 and 11 mg/kg. Cobalamin was 0.16, 0.18 and 0.20 mg/kg. While dietary folic acid was 2.9, 4.8 and 6.3 mg/kg, diets are referred to as low, medium and high 1C diet. All other amino acids were similar between diets. The results showed no differences in growth or feed utilization in the fresh water period, but following the on‐growing salt water period, differences between diets occurred. The fish fed the medium 1C diet showed better growth, as compared to fish fed the low or high 1C diet (p = .009). The medium 1C fed fish showed a relative lower liver weight compared with fish fed low or high 1C diet (p = .025). Condition factor was better in fish fed the medium and high 1C diet as compared to those fed the low 1C diet (p = .0006). As expected, free methionine in liver, plasma and muscle increased by dietary methionine inclusion. Surplus vitamins only had minor effect on tissue concentrations. Based on these findings, we conclude that the micronutrient and methionine level presented in the medium 1C diet improved the growth, liver size and condition factor; however, more research is needed to evaluate the optimal requirement level for each of the 1C nutrients.     

The effect of dietary vitamin A on the immunocompetence of Atlantic salmon (Salmo salar L.)

Atlantic salmon, Salmo salar L. were maintained on diets containing low (0.37 mg kg^–1 diet), normal (1.95 mg kg^–1 diet) and high (15 mg kg^–1 diet) levels of vitamin A fed at 1.5% body weight per day. After 4 months, liver vitamin A levels reflected dietary intake and growth rates of all three groups were similar. Kidney leucocyte migration and serum bactericidal activity were found to be significantly reduced in fish fed low levels of vitamin A. On the other hand, high levels of vitamin A in the diet were found to augment serum antiprotease activity relative to the levels found in the other dietary groups. However, phagocyte respiratory burst activity, bactericidal activity and eicosanoid production were unaffected by the dietary vitamin A regime, as were lymphocyte functions (lymphokine and antibody production) and both serum lysozyme and classical complement activity. That the overall immunomodulatory effect of vitamin A was small was reflected in the resistance to Aeromonas salmonicida. No significant differences were found between the different vitamin A intake groups despite a trend to decreased resistance in the low vitamin A diet group.     

Effects of dietary vitamin C on growth and parr-smolt transformation in Atlantic salmon, Salmo salar L.

Atlantic salmon (Salmo salar) parr were fed fish meal based pelleted diets supplemented with graded levels of ascorbate-2-monophosphate (AP), equivalent to 0, 20, 60 and 1000 mg ascorbic acid (AA) kg”¹ throughout smoltification on a continuous light regime from February to June. No differences were observed in growth rate and body length distribution between the dietary regimes. The condition factor and the hepatosomatic index were somewhat elevated in fish fed no vitamin C throughout the smoltification, which can reflect changes in lipid metabolism in fish with suboptimal vitamin C nutrition. Sea water challenge tests (exposure to sea water with salinity of 34 gL^?1 and ambient temperature for 24 h) performed monthly did not reveal differences attributed to the vitamin C status, as measured by mortality, serum chloride and cortisol concentrations, haematological parameters and liver and head kidney ascorbate concentrations after 24 h. Elevated serum cortisol concentrations most probably reflected stress in the challenge tests, and some lower concentrations in fish fed high vitamin C levels may indicate a certain stress-ameliorating effect. The present results do not, however, support the anticipation of increased requirement of dietary vitamin C above the minimum requirement during smoltification in Atlantic salmon.     

Effects of dietary oxidized oil and vitamin E on the growth,blood parameters and body composition of juvenile Atlantic cod Gadus morhua (Linnaeus 1758)

The effects of oxidized dietary lipid and the role of vitamin E on the growth performance, blood parameters and body composition of juvenile Atlantic cod (Gadus morhua) were evaluated over a 9‐week feeding period. Four isonitrogenous experimental diets containing fresh or oxidized fish oil with or without added vitamin E (α‐tocopherol or mixed tocopherols) were fed to juvenile cod. The oxidized lipid used had a peroxide value of 94 mEq kg^?1 oil. No significant (P>0.05) differences in growth performance (weight gain and specific growth rate) or feed utilization (feed consumption and feed efficiency ratio) were observed when oxidized dietary lipid was used. The hepatosomatic index (HSI), viscerosomatic index (VSI) and haematocrit did not show any significant (P>0.05) differences among the treatments. However, erythrocyte osmotic fragility (EOF), referred to as susceptibility to haemolysis, of fish fed oxidized oil without added vitamin E was high in comparison with those fed unoxidized oil. Supplementation with α‐tocopherol appeared to decrease haemolysis, but mixed tocopherols had no significant (P>0.05) effect on EOF. The proximate composition of fish whole body was also affected by diet treatment. Fatty acid composition of liver total lipid reflected that of dietary lipid. Variations in tissue (liver and muscle) fatty acid composition among the treatments followed the same trend as those of the dietary fatty acids. Fish fed fresh oil had a higher proportion of polyunsaturated fatty acids (PUFA) in muscle and liver lipid than those fed oxidized oil. The results suggest that oxidized dietary oil affected juvenile Atlantic cod in certain tissues and that these effects could be alleviated by supplementation of sufficient amounts of vitamin E in the diet.     

Comparative effects of dietary Na+-lactate on Arctic char, Salvelinus alpinus L., and Atlantic salmon, Salmo salar L.

Arctic char, Salvelinus alpinus L., and Atlantic salmon, Salmo salar L., were fed a commercial diet with or without supplementation of 1.5% Na⁺-lactate. Dietary Na⁺-lactate enhanced growth of Arctic char, while that of salmon was unaffected. Dietary ¹⁴C-lactate was retained for significantly longer in the stomach of Arctic char than that of Atlantic salmon. Changes in intestinal cholytaurin hydrolase activity, a bacterially produced enzyme, may indicate that dietary lactate affects the intestinal microbiota of Arctic char but not that of Atlantic salmon. Analysis of bile acids of char showed that dietary Na⁺-Iactate influenced neither intestinal nor gallbladder bile acid composition. Although Arctic char possesses the classical entero-hepatic circulation pathway, no extra loss of bile acids from the fish was observed. It is concluded that the retention time of diet in the stomach of char is significantly longer than that of salmon. This may increase the antibacterial action of lactate in the former, favouring the colonization of lactic-acid-tolerant bacteria in the intestinal tract, some of which produce the enzyme cholytaurin hydrolase.     

Three different levels of dietary vitamin D3 fed to first-feeding fry of Atlantic salmon (Salmo salar L.): effect on growth, mortality, calcium content and bone formation

Atlantic salmon ( Salmo salar L.) fry were reared on a fishmeal-based diet with three different levels of vitamin D₃ (0.2, 5 and 57 mg vitamin D₃ kg^–1 feed, ww) from first-feeding for 14 weeks. No significant differences were recorded in weight, length, specific growth rate, mortality, or kidney calcium concentration between the different dietary groups. No skeletal malformations or histopathological changes were recorded in any of the dietary groups. These results suggest Atlantic salmon fry to be highly tolerant of megadoses of vitamin D₃ over a limited period of time.     

Tissue distribution of vitamin D3 in Atlantic salmon Salmo salar: effect of dietary level

Atlantic salmon Salmo salar were given three dietary doses of vitamin D₃ for a period of 11 weeks: diet groups I, II and III received a 0.04, 2.21 and 28.68 μg g⁻¹ diet of vitamin D₃, respectively. The tissue distribution of vitamin D₃ was investigated, and between diet groups II and III, the level of vitamin D₃ found in the tissues was increased by a factor similar to the increased level in the feed. No effects were observed on weight gain, survival, plasma level of calcium, red blood cell count or haematocrit, relative to the dietary levels of vitamin D₃. The results showed that while the plasma concentration of 25(OH)D₃ increased between diet groups II and III, the concentration of 1,25(OH)₂D₃ decreased.     

Influence of vitamin C on the immune system of salmonids

Abstract. Trials were run to determine the immunomodulatory effect of dietary vitamin C in rainbow trout. Oncorhynchus mykiss (Walbaum), and Atlanticsalmon, Salmo Salar L. We first investigated whether depletion of ascorbic acid (AA) could depress the immune system. Subsequently, we focused our studies on the stimulatory effect of a high dietary dose of stable vitamin C derivatives (1000mg AA-equivalent per kg of feed) in order to determine their prophylactic role. Three trials were run with rainbow trout fed, for periods of time varying from 2 to 6 months, a high dietary dose of ascorbate-2-polyphosphate (AAPP) or L-ascorbate-2-monophosphate calcium salt (AAMP) equivalent to 1000mg AA per kg of feed. The high dietary level of vitamin C was compared to 60mg AA-equivalent per kg of feed. Another experiment was conducted with Atlantic salmon pre-fed AAPP at 60mg/kg for 6 months followed by AAPP at 1000mg/kg for 2 months. Various immune parameters were tested such as mitogen-induced proliferation, serum complement level, phagocytosis and natural cytotoxicity. Leucocyte and plasma AA contents were also determined. The immune response in vitamin-C deficient trout was not strongly different from that in trout fed the minimal growth requirement level. Serum complement level was not affected by vitamin C. A high dietary dose of vitamin C was found to increase trout and salmon leucocyte AA content, mitogen-induced proliferation of lymphocytes, and chemiluminescence response of leucocytes with a higher constancy, when the cells were stimulated with opsonized zymosan and with luminol as a substrate. Natural cytotoxicity was enhanced in trout fed a high dietary dose of vitamin C. The results of these immunity studies support supplementation levels of vitamin C which are much higher than the minimal requirement known to prevent deficiency symptoms and promote normal growth. Further investigations on the time-dose response are needed to define quantitatively the high dietary dose of vitamin C.     

The influence of environmental temperature on the apparent nutrient and fatty acid digestibility in Atlantic salmon (Salmo salar L.) fed finishing diets containing different blends of fish oil, rapeseed oil and palm oil

A 12‐week feeding trial was conducted to investigate the interactive effects between water temperature and diets supplemented with different blends of fish oil, rapeseed oil and crude palm oil (CPO) on the apparent nutrient and fatty acid digestibility in Atlantic salmon. Two isolipidic extruded diets with added fish oil fixed at 50% and CPO supplemented at 10% or 25% of total added oil, at the expense of rapeseed oil, were formulated and fed to groups of Atlantic salmon (about 3.4 kg) maintained in floating cages. There were no significant effects (P>0.05) of diet on growth, feed utilization efficiency, muscle total lipid or pigment concentrations. Fatty acid compositions of muscle and liver lipids were mostly not significantly different in salmon fed the two experimental diets but showed elevated concentrations of 18:1n‐9 and 18:2n‐6 compared with initial values. Decreasing water temperatures (11–6°C) did not significantly affect protein, lipid or energy apparent digestibilities of the diets with different oil blends. However, dry matter digestibility decreased significantly in fish fed the diet with CPO at 25% of added oil. Increasing dietary CPO levels and decreasing water temperature significantly reduced the apparent digestibility (AD) of saturated fatty acids. The AD of the saturates decreased with increasing chain length within each temperature regimen irrespective of CPO level fed to the fish. The AD of monoenes and polyunsaturated fatty acids was not affected by dietary CPO levels or water temperature. No significant interaction between diet and water temperature effects was detected on the AD of all nutrients and fatty acids. The results of this study showed that the inclusion of CPO up to about 10% (wt/wt) in Atlantic salmon feeds resulted in negligible differences in nutrient and fatty acid digestibility that did not affect growth performance of fish at the range of water temperatures generally encountered in the grow‐out phase.     

Net production of Atlantic salmon (FIFO,Fish in Fish out < 1) with dietary plant proteins and vegetable oils

Adult Atlantic salmon (Salmo salar; approximately 800 g start weight) were fed diets with a high replacement of fish meal (FM) with plant proteins (70% replacement), and either fish oil (FO) or 80% of the FO replaced by olive oil (OO), rapeseed oil (RO) or soybean oil (SO) during 28 weeks in triplicate. Varying the lipid source only gave non‐significant effects on growth and final weight. However, a significantly reduced feed intake was observed in the SO fed fish, and both feed utilization and lipid digestibility were significantly reduced in the FO fed fish. Limited levels of dietary 18:3n‐3, precursor to EPA and DHA, resulted in no net production of EPA and DHA despite increased mRNA expression of delta‐5‐desaturase and delta‐6‐desaturase in all vegetable oil fed fish. Net production of marine protein, but not of marine omega‐3 fatty acids, is thus possible in Atlantic salmon fed 80% dietary vegetable oil and 70% plant proteins resulting in an estimated net production of 1.3 kg Atlantic salmon protein from 1 kg of FM protein. Production of one 1 kg of Atlantic salmon on this diet required only 800 g of wild fish resources (Fish in ‐ Fish out < 1).     

Growth and survival of Atlantic salmon, Salmo salar L. fed different dietary levels of astaxanthin. Juveniles

Atlantic salmon, Salmo salar L., juveniles, with a mean initial weight of 1.75 g, were fed casein-based purified diets which had been supplemented with different levels of astaxanthin for a 10-week period. The astaxanthin content of the diets ranged from 0 to 190 mg kg^?1 dry diet. The growth and survival of the juveniles were recorded throughout the experiment. The proximate composition, astaxanthin and vitamin A content were determined from whole-body samples at the start and termination of the experiment. The dietary treatment was found to affect growth significantly (P < 0.05). A reduction in the mean weight of the juveniles was observed in the groups fed the diets without astaxanthin supplementation. There was no difference in growth rate between the fish in the groups fed the diets containing 36 or 190 mg astaxanthin kg^?1 dry diet, whereas the fish in the group fed the diet containing 5.3 mg astaxanthin kg^?1 dry diet had a lower growth rate. There was a tendency to higher survival in the groups fed the diets containing astaxanthin when compared with the groups fed the non-supplemented diets. The moisture and ash contents were significantly lower and the lipid content was higher in the groups fed the astaxanthin-supplemented diets. The astaxanthin and the vitamin A concentrations in the fish were found to be dependent upon the dietary astaxanthin dose; the highest values were found in the fish fed the diet with the highest astaxanthin content. These results strongly indicate that astaxanthin functions as a provitamin A for juvenile Atlantic salmon. The body storage of vitamin A increased in the fish fed the diets containing astaxanthin. However, the increase was low in the fish fed the diet containing 5.3 mg astaxanthin kg^?1 dry diet.