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1.
This study compared the efficacy of different dietary algae on the growth and reproduction of the cyclopoid copepod Cyclopina kasignete, a potential live food species for fish larvae in aquaculture. The experimental diets for the copepod consisted of three monoalgal diets (Nannochloropsis oculata, Tisochrysis lutea and dry Melosira sp.) and two mixed algae diets (T. lutea?+?N. oculata, T. lutea?+?dry Melosira sp.). The experiment was carried out for 30 days, and the population growth, survival and reproductive performance (generation time, hatching rate, life spawning times, daily offspring production, eggs per sac, lifespan and sex ratio) were used to assess the responses of C. kasignete to different food types. Population growth, survival and reproductive capacities of C. kasignete were significantly affected by the mono and binary species of algal diets. The results showed that copepods exhibited superior growth, survival and productivity when fed on fresh T. lutea, dry Melosira sp. and a mixture of both species compared to other dietary treatments. Copepods produced comparable growth, survival and productivity when fed on diatoms (dry Melosira sp.) as a single or in combination with other algae. This study indicates that cyclopoid copepod C. kasignete grow fast and have the potential to serve as a live food for aquaculture. The algae T. lutea, dry Melosira sp. and their combination are appropriate food to sustain the growth and reproduction of this copepods in mass culture as a potential live food in fish hatchery.  相似文献   

2.
We compared the development and fatty acid content of the harpacticoid copepods Tachidius discipes and Tisbe sp. fed with different microalgal species (Dunaliella tertiolecta, Rhodomonas sp., Phaeodactylum tricornutum, Isochrysis galbana and a concentrate of Pavlova sp.), which differed in cell size and fatty acid composition. Tisbe could develop in 11 days with every alga to the same average stage, whereas Tachidius developed poorly when fed with Isochrysis and Dunaliella. Feeding with Phaeodactylum resulted in a fast development of both copepods at low algal concentrations. However, reproduction was higher with Rhodomonas as food than with the other algae. Fatty acid compositions of copepods were influenced by their food source, but both were able to convert docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from precursors. Tachidius fed with Rhodomonas or Phaeodactylum was closest to the DHA/EPA/arachidonic acid (ARA) ratio of 10 : 5 : 1 considered optimal for some marine fish larvae. Tachidius showed similar development and reproduction capacity as Tisbe, but requested higher absolute fatty acid contents in the diet. Tisbe was superior in the utilization of bacteria as additional food source and the bioconversion of precursor fatty acids. Phaeodactylum and Rhodomonas are recommendable food sources for both copepod species, but Phaeodactylum is more easily cultured.  相似文献   

3.
The brackish cyclopoid copepod Apocyclops royi is used in Taiwanese aquaculture industry as a prey for fish larvae. This study investigated the effects of seven microalgal diets, namely single‐species diets of Isochrysis galbana (ISO), Nannochloropsis oculata (NAN), and Tetraselmis chui (TET), two‐species diets (ISO+NAN, ISO+TET and TET+NAN), and a three‐species diet (ISO+NAN+TET), on the population growth, female fecundity and fatty acid composition of A. royi. For reproductive traits, the combination ISO+NAN was found to be the most supportive diet for both population growth and female fecundity. For nutritional value, copepods fed ISO and ISO+NAN were detected to have the highest content of docosahexaenoic acid (DHA) (18.99% and 10.73% total fatty acid, respectively) and, more importantly, a high DHA/EPA ratio (6.09 and 4.09, respectively). Additionally, a comparison of fatty acid composition between copepods and microalgae gives a tentative indication that A. royi may have the ability to synthesize long‐chain polyunsaturated fatty acids (PUFA) from short‐chain PUFA. Our findings illustrate that ISO+NAN is the most suitable microalgal diet for mass culturing A. royi because it increases productivity and enhances the nutritional value of the copepods for use as fish larvae prey.  相似文献   

4.
The importance of dietary 20:5n‐3 (EPA), 22:6n‐3 (DHA) and 20:4n‐6 (ARA) for growth, survival and fatty acid composition of juvenile cockles (Cerastoderma edule) was investigated. Cockles of 6.24 ± 0.04 mm and 66.14 ± 0.34 mg (live weight) were distributed into three treatments where live microalgae diets were fed constantly below the pseudofaeces production threshold, for three weeks. Diets had distinct fatty acid profiles: high EPA (53% Chaetoceros muelleri + 47% Pyramimonas parkeae), no DHA (47% Brachiomonas submarina + 53% Tetraselmis suecica) and low ARA concentrations (73% P. parkeae + 27% Phaeodactylum tricornutum). Growth was positively affected by high EPA and low ARA diets, whereas no significant growth was observed for the no DHA diet. High mortality of cockles fed no DHA diet raises questions about its suitability for cockles. In balanced diets with EPA and DHA, lower concentrations of ARA do not limit growth. The impact of dietary fatty acids was evident in the fatty acids of neutral and polar lipids of cockles. In polar lipids of all cockles, there was a decrease in EPA, in contrast to an increase in DHA. The combination of EPA and DHA in a live microalgae diet was beneficial for the growth and survival of juvenile cockles.  相似文献   

5.
This study is the first attempt to condition broodstock Babylonia areolata using formulated diets under hatchery conditions. Samples of spotted babylon egg capsules from broodstock fed either a formulated diet or a local trash fish, carangid fish (Seleroides leptolepis) for 120 days were analyzed for proximate composition and fatty acid composition. The formulated diet contained significantly higher levels of arachidonic acid (20:4n − 6; ARA), eicosapentaenoic acid (20:5n − 3; EPA) and docosahexaenoic acid (22:6n − 3; DHA) than those of the local trash fish. The formulated diet also had significantly higher ratios of DHA/EPA and (n − 3)/(n − 6) PUFA than those of local trash fish but not for the ARA/EPA ratio. The compositions of egg capsules produced from broodstock fed formulated diet contained significantly more ARA, EPA and DHA compared to broodstock fed the local trash fish. The ARA/EPA and DHA/EPA ratios in egg capsules were significantly higher in the trash fish—fed group compared to those fed the formulated diet. However, (n − 3)/(n − 6) PUFA ratios in egg capsules produced from broodstock fed the formulated diet did not differ significantly compared to those from broodstock fed the local trash fish. The relatively low DHA/EPA, ARA/EPA and (n − 3)/(n − 6) ratios in the egg capsules produced from the formulated diet—fed broodstock B. areolata suggested that this diet is inferior, when compared to the traditional food of trash fish.  相似文献   

6.
This study examined the dietary requirement of arachidonic acid (ARA) when that of linoleic acid (LOA), the natural precursor to ARA, was also satisfied with linolenic acid (LNA) and also with and without the other key dietary highly unsaturated fatty acids (HUFA). Growth by prawns fed diets supplemented with ARA was poorer than in diets where it was not present. Supplementation of ARA to diets with either optimized HUFA or just optimised poly unsaurated fatty acids (PUFA) (i.e. LOA, LNA) resulted in poorer growth. Growth was poorest by prawns (215 ± 13%) fed diets with ARA supplemented at 20% of the total fatty acids but including 7% LOA, 21% LNA and 4% of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Growth was best in prawns fed diets devoid of ARA but with 7% LOA and 21% LNA (350 ± 19%). Prawns fed the reference diet (348 ± 21%) and the other diet devoid of ARA but containing about 7% LOA, 21% LNA and 4% of both EPA and DHA (345 ± 18%) had similar growth. The growth responses were not effects of altered lipid or fatty acid digestibilities. Indeed supplementation of ARA to the diet marginally improved the digestibility of the total neutral lipid in the diet and the digestibilities of some other dietary fatty acids. The amount of lipid in the digestive glands of prawns fed with the diets was reduced by the inclusion of ARA in the dietary lipids. Composition of the lipids in the digestive gland (DG) of the prawns was almost directly related to the composition of their dietary lipids. The proportion of ARA in the total fatty acids increased with level of supplementation of dietary ARA. An increased level of dietary ARA reduced the proportion of EPA, DHA in the DG lipid and also the total n‐3 and n‐6 fatty acids in the DG lipid. The results of this study support that addition of ARA to the diet of Penaues monodon when the other key essential fatty acids (EFA) have been optimized, does not improve their growth performance. It is suggested that key cause for this response may lie in the importance of the balance of the n‐3 to n‐6 fatty acids in the diet of these animals.  相似文献   

7.
Evidence confirms that polyunsaturated fatty acids (PUFAs), arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid, DHA are involved in growth as well in pigmentation of marine fish larvae.In the present study we examined the performance of common sole larvae reared on Artemia enriched with 10 formulated emulsions, differing in inclusions of ARA, EPA, and DHA. The specific growth rate of the sole larvae until late metamorphosis, 21 days after hatching (dah) was 20 to 27% d− 1. Even though the relative tissue essential fatty acid (EFA) concentrations significantly reflected dietary composition, neither standard growth nor larval survival were significantly related to the absolute concentrations of ARA, EPA and DHA or their ratios. This suggests low requirements for essential polyunsaturated fatty acids (PUFAs) in common sole. Malpigmentation was significantly related to increased dietary ARA content. However, pigmentation was not affected by inclusion levels of EPA or DHA when ARA was high. This, and no relation between DHA: EPA or ARA: EPA ratios and pigmentation and only a weak relation to ARA: DHA ratio, advocate for that it is the absolute concentration of ARA in larval tissues, that is responsible for malpigmentation rather than the relative concentration to other PUFAs.Within malpigmentation, the trait “albinism” was characterised by an abnormal incomplete eye migration, but this trait is suggested not to be related to dietary ARA. Furthermore, albinism resulted in a lower growth rate, which suggests that visual aberrations affected prey capture.  相似文献   

8.
Farmed eels had lower levels of arachidonic acid (20:4 n‐6) (ARA) and higher ratios of eicosapentaenoic acid (20:5 n‐3) (EPA):ARA compared to wild European eels collected from the Baltic Sea and southern Norwegian coast. Eels fed a formulated feed (JD) with a distribution of essential fatty acids (EFA) resembling wild European eel were sampled after 0, 5, 10, 14 and 44 weeks of feeding to examine changes in fatty acid composition (FAC) in ovaries, visceral fat and muscle. The results showed a slow but steady incorporation of EFA. Lipids are incorporated in the oocytes early in oogenesis, and the leading cohort of oocytes is rich in lipid droplets before the onset of vitellogenesis. This indicates that feeding with optimized broodstock feeds should start early to allow the incorporation of EFA in the first cohort of oocytes. At least 14 weeks of feeding is required to change lipid EFA in broodstock eel to resemble EFA in the diet or in wild fish. After 44 weeks of feeding, ARA was significantly higher in the neutral lipids of ovaries (1.9%) compared to visceral fat (1.2%) or muscle (1.0%). EPA:ARA ratios decreased two‐ to threefold in all tissues examined during that time. ARA and docosahexaenoic acid (22:6 n‐3) (DHA) had accumulated in ovarian polar lipids.  相似文献   

9.
The purpose of this study was to evaluate the effect of varying dietary levels of highly unsaturated fatty acids (HUFAs) in live prey (Artemia nauplii and a calanoid copepod, Schmackeria dubia) on the growth performance, survival, and fatty acid composition of the lined seahorse, Hippocampus erectus, juveniles. Artemia nauplii were enriched with a commercial product (SS? 50DE‐microcapsule as HUFA source, 2/3 DHA, 1/3 EPA. Shengsuo Fishery Feed Research Center of Shandong Province, Qingdao, China) at four concentrations of 0.0, 14.0, 28.0, and 56.0. Newly hatched juveniles were cultured for 35 days. The content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n‐3 HUFAs in the Artemia nauplii was positively related to the enrichment concentration. At the end of the trials, growth performance of the juveniles was positively related to the enrichment concentration as well. However, the juveniles fed prey enriched with the highest concentration of enrichment (56.0 μL/L) had the significantly lower (P < 0.05) survival rate. The juveniles fed the copepod had the best growth performance and the highest survival rate, suggesting that the copepod, S. dubia, is suitable for feeding the seahorse juveniles. The comparisons between the growth, survival, and fatty acid profiles of the juveniles fed Artemia and copepods indicate that the seahorse juveniles require dietary levels of DHA beyond those achieved by enriching prey with the HUFA enrichment. Surplus EPA resulted from an imbalance between DHA and EPA in the enriched Artemia nauplii probably caused an adverse effect on the seahorse juveniles. This study suggests that DHA and EPA requirement of the lined seahorse juveniles is roughly 32% of total fatty acid, and the optimal DHA/EPA ratio for the species is circa 4:1. To avoid an adverse effect resulting from excessive EPA, maximum proportion of EPA in enriched Artemia nauplii should not exceed 13% of total fatty acid, and a recommended minimum DHA/EPA ratio in the enriched Artemia nauplii is 1.46. Arachidonic acid (20:4n‐6) might not be an essential fatty acid for the seahorse juveniles.  相似文献   

10.
This study investigated the effects of varying dietary levels of decosahexaenoic acid (DHA) on growth performance, proximate composition and whole body fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Triplicate groups of fish (30.55 ± 0.08 g) were fed diets containing 5.2%, 9.31% and 13.38% DHA (% of total fatty acids) or 0.85%, 1.52% and 2.18% DHA on dry diet weight for diets 1, 2 and 3 respectively. Survival was not affected by dietary DHA levels. The growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P < 0.05) higher than those fed diet 1, although these parameters in diets 2 and 3 did not differ significantly (P > 0.05). Whole body lipid and fatty acid profiles were influenced by dietary DHA levels. Significantly higher n‐3 fatty acids particularly DHA, DHA:EPA(eicosapentaenoic acid) ratios and n‐3:n‐6 ratios were observed in fish fed diets 2 and 3 compared to those fed diet 1. Better growth performance and higher whole body DHA:EPA (2.31, 2.29) ratios and n‐3:n‐6 ratios (2.17, 2.12) observed in fish fed diets 2 and 3, respectively, suggests that silver pomfret juveniles have a higher requirement for n‐3 fatty acids, notably DHA for optimum growth and survival.  相似文献   

11.
The cyclopoid copepod Apocyclops dengizicus was isolated from a marine shrimp pond, Penaeus monodon, Kuala Selangor, Malaysia, and reared in the laboratory for 3 months to establish a pure population stock. Amino acids and fatty acids of A. dengizicus were determined when fed Chaetocerous calcitrans (C), Tetraselmis tetrathele (T) and their combination (CT) (1:1 by number). The protein contents in A. dengizicus that received C, T and CT were 46.8%, 60.5% and 55.3% of dry weight respectively. Correspondingly, the lipid was 19.0%, 17.8% and 19.1% of dry weight for C, T and CT respectively. The A. dengizicus cultured on C, T and CT had total essential amino acids without tryptophan measurement of 57.1, 60.3 and 67.8 and total non‐essential amino acids of 42.9%, 40.0% and 32.2% of total amino acids. The fatty acid content of A. dengizicus showed that it was able to synthesize docosahexenoic acid (22:6n‐3, DHA), eicosapentaenoic acid (20:5n‐3, EPA) and arachidonic acid (20: 4n‐6, ARA) from examined microalgal diets. The DHA:EPA:ARA ratios of A. dengizicus fed on C, T and CT were 6.8:3.0:1, 14.0:5.8:1 and 11.6:2.6:1 respectively. Apocyclops dengizicus could be suitable live food for larval fish and shrimp rearing because it meets their nutritive requirements.  相似文献   

12.
The effects of feeding different sources of brine shrimp nauplii with different fatty acid compositions on growth, survival, and fatty acid composition of striped bass, Morone saxarilis and palmetto bass (M. saxatilis x M. chrysops) were determined. The sources of brine shrimp were Chinese (CH), with a high percentage of 20:5(n-3), eicosapentaenoic acid (EPA), and Colombian (COL), San Francisco Bay (SFB), and Great Salt Lake (GSL), with low percentages of EPA but high percentages of 18:3(n-3), linoienic acid. None of the brine shrimp sources contained a measurable amount of 22:6(n-3), docosahexaenoic acid (DHA). After enrichment with menhaden oil to increase the content of EPA and DHA, the GSL brine shrimp nauplii were also fed to hybrid striped bass.Growth and survival of fish larvae fed brine shrimp nauplii with high percentages of EPA and DHA (CH and GSLE) were higher (P < 0.05) than those of fish fed brine shrimp with a low percentage of EPA (COL, SFB, and GSL). The ratio of 20:3(n-9) eicosatrienoic acid (ETA), to DHA in polar lipids (phospholipids) of fish, traditionally used as an indicator of essential fatty acid (EFA) sufficiency of the diet, was not a reliable indicator of essential fatty acid sufficiency of diets for larval striped bass and hybrid striped bass. However, the ratio of ETA to EPA appears to be an appropriate indicator. An ETA-to-EPA ratio in phospholipids of less than 0.10 is consistent with an EFA sufficient diet.  相似文献   

13.
The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from first feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and 10% total fatty acids=TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed significantly (P<0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also significantly (P<0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L−1) challenge, no significant differences (P>0.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50=25.6 min) and larvae fed 0% DHA (ST50=18.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHA with increasing ARA within the range of 0–6% showed improved growth and survival from first feeding through metamorphic stages.  相似文献   

14.
Y. Wang  M. Li  K. Filer  Y. Xue  Q. Ai  K. Mai 《Aquaculture Nutrition》2017,23(5):1113-1120
This trial was conducted to evaluate the effects of replacing dietary fish oil with Schizochytrium meal for Pacific white shrimp (Litopenaeus vannamei) larvae (initial body weight 4.21 ± 0.10 mg). Six test microdiets were formulated using Schizochytrium meal to replace 0 g/kg, 250 g/kg, 500 g/kg, 750 g/kg, 1000 g/kg or 1500 g/kg fish oil DHA. No significant differences were observed in survival, growth, final body length and activities of digestive enzyme among shrimp fed different diets (p > .05). No significant differences were observed in C20:5n‐3 (EPA) in muscle samples (p > .05). C18:3n‐3 and C20:4n‐6 in muscle increased as Schizochytrium meal replacement level increased (p < .05). No significant differences were observed in C22:6n‐3 (DHA) and n‐3 fatty acids among shrimp fed diets that algae meal replaced 0 g/kg ‐ 1000 g/kg of fish oil. Shrimp fed diet R150 had higher DHA content than other groups and had higher n‐3 fatty acids than that of shrimp fed diets R50, R75 and R100 (p < .05). C18:2n‐6, PUFA and n‐6 fatty acids in muscle increased, while n‐3/n‐6 ratio decreased with increasing algae meal replacement level from 0 g/kg to 1000 g/kg (p < .05). In conclusion, Schizochytrium meal could replace 1500 g/kg fish oil DHA in the microdiets without negatively affecting shrimp larvae survival, growth and activities of digestive enzyme.  相似文献   

15.
We examined the effect of dietary eicosapentaenoic acid (EPA, 20:5n‐3) on growth, survival, pigmentation and fatty acid composition of Senegal sole larvae. From 3 to 40 days post‐hatch (dph), larvae were fed live food that had been enriched using one of four experimental emulsions containing graduated concentrations of EPA and constant docosahexaenoic acid (DHA, 22:6n‐3) and arachidonic acid (ARA, 20:4n‐6). Final proportions of EPA in the enriched Artemia nauplii were described as ‘nil’ (EPA‐N, 0.5% total fatty acids, TFA), ‘low’ (EPA‐L, 10.7% TFA), ‘medium’ (EPA‐M, 20.3% TFA) or ‘high’ (EPA‐H, 29.5% TFA). Significant differences among dietary treatments in larval length were observed at 25, 30 and 40 dph, and in dry weight at 30 and 40 dph, although no significant correlation could be found between dietary EPA content and growth. Eye migration at 17 and 25 dph was affected by dietary levels of EPA. Significantly lower survival was observed in fish fed EPA‐H diet. Lower percentage of fish fed EPA‐N (82.7%) and EPA‐L (82.9%) diets were normally pigmented compared with the fish fed EPA‐M (98.1%) and EPA‐H (99.4%) enriched nauplii. Tissue fatty acid concentrations reflected the corresponding dietary composition. ARA and DHA levels in all the tissues examined were inversely related to dietary EPA. This work concluded that Senegal sole larvae have a very low EPA requirement during the live feeding period.  相似文献   

16.
The aim of this study was to determine if algal products rich in DHA or ARA are able to completely replace fish oil in microdiets for marine fish larvae, gilthead seabream and if extra supplementation with EPA may further enhance larval performance. For that purpose, 20 day‐old gilthead seabream larvae of 5.97 ± 0.4 mm mean total length and 0.12 ± 0.001 mg mean dry body weight were fed with five microdiets tested by triplicate: a control diet based on sardine oil; a diet containing AquaGrow® DHA (diet DHA) to completely substitute the sardine oil; a diet containing AquaGrow® ARA (diet ARA); a diet containing both products, AquaGrow® DHA and AquaGrow® ARA to completely substitute the fish oil; and, a diet containing both products, AquaGrow® DHA and AquaGrow® ARA, together with an EPA source. Temperature, air and salinity activity tests were also performed to detect larval resistance to stress. At the end of the experiment, final survivals did not differ among groups. The microorganism produced DHA was able to completely replace fish oil in weaning diets for gilthead seabream without affecting survival, growth or stress resistance, whereas the inclusion of microorganism produced ARA did not improve larval performance. Moreover, addition of EPA to diets with total replacement of fish oil by microorganism produced DHA and ARA, significantly improved growth in terms of body weight and total length. The results of this study denoted the good nutritional value of microorganisms produced DHA as a replacement of fish oil in weaning diets for gilthead seabream, without a complementary addition of ARA. However, dietary supplementation of EPA seems to be necessary to further promote larval performance.  相似文献   

17.
The nutritional requirements of pikeperch larvae have been sparsely examined. Dietary polyunsaturated fatty acids, arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may affect growth and physiological stress response in marine fish larvae, but these mechanisms have not received as much attention in freshwater fish. Pikeperch larvae were reared on Artemia from day 3 until 21 days posthatch. Artemia were enriched with six formulated emulsions, with inclusion of either fish oil, pure olive oil (POO) or olive oil supplemented with various combinations of ARA, EPA and DHA. Larval tissue FA was significantly related to the content in the diets, but larval growth was similar for all treatments. When exposed to stress by confinement in small tanks with culture tank water or saline water (15 g L?1.), mortality in larvae treated with POO was significantly higher than in the remaining treatments while tissue cortisol contents in these fish seemed lower. The findings of a lower stress response in larvae fed POO may be related to the lower tissue content in these larvae of essential fatty acids especially DHA but also EPA and ARA.  相似文献   

18.
This study aimed at comparing fatty acid contents of rotifers cultured with different methods after nutritional enrichment in order to evaluate the rotifer quality produced by these methods. Rotifers were cultured using either a batch or a continuous culture. From the batch culture, three experimental subpopulations were used, sampled from the culture at 1, 24, and 48 h after rotifer inoculation. The continuous culture was performed with two tanks; one was for cultivation with continuous feeding and water supply (cultivation tank), and another was for harvesting from the cultivation tank by overflow (harvest tank). From the continuous culture, two subpopulations were used: one from the cultivation and one from the harvest tank. Nutritional enrichment was performed after each culture. Each population was enriched with Nannochloropsis oculata or a commercial enrichment diet. When the enrichment was performed with N. oculata on populations at 24 h after inoculation originating from either of the two tanks of continuous culture or the batch culture tank, a higher quantity of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) was obtained from the two tanks of continuous culture. The same results were obtained when enrichment diet was used, this time including docosahexaenoic acid (DHA).  相似文献   

19.
Five purified diets containing AA (20:4n-6) at 0.02–0.78% dry weight and DHA (22:6n-3) at 0.93–0.17% dry weight were fed to duplicate groups of juvenile turbot (Scophthalmus maximus) of initial weight 0.87 g for a period of 11 weeks. The dietary DHA:AA ratio ranged from 62 to 0.2. Incorporation of AA into liver phospholipids increased with increasing dietary AA input. Phospholipids from fish fed diets containing 0.02, 0.06 and 0.11% of dry weight as AA generally contained less AA compared to fish fed fish oil while those fed diets containing 0.35 and 0.78% of dry weight as AA had higher AA levels in their phospholipids. The highest levels of AA were found in PI but the greatest percentage increase in AA incorporation was in PE and PC. Brain phospholipid fatty acid compositions were less altered by dietary treatment than those of liver but DHA content of PC and PE in brain was substantially lower in fish fed 0.93% pure DHA compared to those fed fish oil. This suggests that dietary DHA must exceed 1% of dry weight to satisfy the requirements of the developing neural system in juvenile turbot. In both tissues, (20:5n-3) concentration was inversely related to both dietary and tissue PI AA concentration. Similar dietary induced changes in AA, EPA and DHA concentrations occurred in the phospholipids of heart, gill and kidney. PGE2 and 6-ketoPGF1 were measured in homogenates of heart, brain, gill and kidney. In general, fish fed the lowest dietary AA levels had reduced levels of prostaglandins in their tissue homogenates while those fed the highest level of AA had increased prostaglandin levels, compared to fish fed fish oil. In brains, the PGE2 concentration was only significantly increased in fish fed the highest dietary AA.Abbreviations AA arachidonic acid - DHA docosahexaenoic acid - EFA essential fatty acid - EPA eicosapentaenoic acid - HPTLC high performance thin-layer chromatography - HUFA highly unsaturated fatty acid - PC phosphatidylcholine - PE phosphatidylethanolamine - PGE prostaglandin E - PGE prostaglandin E - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography  相似文献   

20.
This study compared the efficacy of four products that are commonly used in hatchery for nutritional enhancement of rotifer Brachionus plicatilis as the starter food for yellowtail kingfish Seriola lalandi larvae. This experiment consisted of one fresh algae and three enrichment products: (1) Fresh algae were a mixture of Nannochloropsis and Isochrysis at 2:1 on a cell concentration basis; (2) S.presso, (Selco S.presso ®, INVE Aquaculture); (3) Algamac 3050® (Aquafauna, USA); (4) Nutrokol ® (Nutra‐Kol, Australia). Survival rates of the fish fed rotifers enriched with fresh microalgae (40.69%) and S.presso (31.21%) were higher than those fed Algamac 3050 (10.31%). On 3 day post hatch (DPH), fish feeding incidence in the fresh algae treatment was significantly higher than that in other treatments. On 6 DPH, fish showed the lowest feeding incidence in the Algamac 3050 treatment. The methods of enrichment did not affect total lipid levels in either rotifer or fish larvae, but Algamac 3050 enrichment achieved the highest DHA/EPA ratio and lowest EPA/ARA ratio in both rotifers and fish larvae. This study indicates that fresh algae can be replaced by S.presso, but Algamac 3050 is not as good as other formula for rotifer enrichment in rearing yellowtail kingfish larvae in this system.  相似文献   

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