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1.
The effect of varying levels of dietary n-3 highly unsaturated fatty acid (HUFA) and docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratios on growth, survival and osmotic stress tolerance of Eriocheir sinensis zoea larvae was studied in two separate experiments. In experiment I, larvae were fed rotifers and Artemia enriched with ICES emulsions with 0, 30 and 50% total n-3 HUFA levels but with the same DHA/EPA ratio of 0.6. In experiment II, larvae were fed different combinations of enriched rotifers and Artemia, in which, rotifers were enriched with emulsions containing 30% total n-3 HUFA, but different DHA/EPA ratio of 0.6, 2 and 4; while Artemia were enriched with the same emulsions, but DHA/EPA ratio of 0.6 and 4. In both experiments, un-enriched rotifers cultured on baker's yeast and newly-hatched Artemia nauplii were used as control diets. Larvae were fed rotifers at zoea 1 and zoea 2 stages; upon reaching zoea 3 stage, Artemia was introduced.Experiment I revealed no significant effect of prey enrichment on the survival of megalopa among treatments, but higher total n-3 HUFA levels significantly enhanced larval development (larval stage index, LSI) and resulted in higher individual dry body weight of megalopa. Furthermore higher dietary n-3 HUFA levels also resulted in better tolerance to salinity stress. Experiment II indicated that at the same total n-3 HUFA level, larvae continuously receiving a low dietary DHA/EPA ratio had significantly lower survival at the megalopa stage and inferior individual body weight at the megalopa stage, but no negative effect was observed on larval development (LSI). The ability to endure salinity stress of zoea 3, zoea 5 and megalopa fed diets with higher DHA/EPA ratio was also improved.  相似文献   

2.
Importance of Docosahexaenoic Acid in Marine Larval Fish   总被引：28，自引：0，他引：28  
Marine finfish require n-3 HUFA such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as essential fatty acids (EFA) for their normal growth. But it remained unclear as to which of the n-3 HUFA, either EPA or DHA, was important. Unlike the freshwater species, the EFA efficiency of EPA and DHA may vary in marine fish. The developing eggs rapidly utilize DHA either for energy or for production of physiologically important substances like prostaglandin.
This report reveals that in marine larval fish DHA is superior to EPA as EFA. In the case of red seabream, feeding rotifers incorporating EPA and DHA or an n-3 HUFA mixture prevented many of the ill-effects observed when the rotifers were low in n-3 HUFA. Apart from the best growth and survival in an activity test for the larvae fed on DHA-rotifer, the incidence of hydrops seemed to be totally prevented dietetically by DHA. Similar results were obtained in larval yellowtail, striped jack, striped knifejaw and flounder. There seems to exist a functional difference between EPA and DHA.  相似文献   

3.
A feeding study was conducted in the winter 2001 to determine the effects of feeding rotifers (Brachionus plicatilis) enriched with various levels of essential fatty acids on the growth and survival of haddock larvae (Melanogrammus aeglefinus). Rotifer enrichment treatments were: 1) mixed algae, 2) high DHA (docosahexaenoic acid, 22:6n-3), 3) high DHA and EPA (eicosapentaenoic acid, 20:5n-3), and 4) DHA, EPA, and AA (arachidonic acid, 20:4n-6). Larvae were fed rotifers enriched with the different treatments from days 1 to 16 post-hatch. From day 17 until 25 all treatment groups were fed rotifers reared on mixed algae and then weaned onto the International Council for Exploration of the SEA (ICES) Standard Reference Weaning diet (http://allserv.rug.ac.t/aquaculture/rend/rend.htm) over a five day period. The experiment was terminated on day 41 post-hatch. The enrichment treatments affected the fatty acid composition of the rotifers and correlated with the accumulation of these fatty acids in the haddock larvae. However, no significant differences in larval growth or survival to 40 days post hatch were detected, suggesting that all treatments provided the minimal essential fatty acid requirements for haddock.  相似文献   

4.
用3种营养强化剂强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,研究牙鲆仔鱼的生长、成活、体脂肪酸的组成。结果表明:用强化的轮虫和卤虫无节幼体投喂牙鲆仔鱼,成活率、增重均显著高于对照组(p<0 01),其中V号强化剂的效果最好,成活率为29 34%,比对照组提高100%;增重倍数为217 90,比对照组提高68 61%;这是由于V号强化剂强化的卤虫无节幼体体内含有较多的AA的缘故,饵料中AA含量的提高,可以提高牙鲆仔鱼的成活率、促进其生长。牙鲆摄食强化过的轮虫、卤虫无节幼体后,其EPA、DHA、n-3HUFA、PUFA的含量随着饵料中含量的升高而升高,这也是牙鲆仔鱼生长速度和成活率提高的重要因素之一。  相似文献   

5.
The effects of dietary n-3 highly unsaturated fatty acid (n-3 HUFA) on eggs and larval quality were investigated in the Chilean flounder Paralichthys adspersus . Broodstock were fed with three formulated diets with similar proximate compositions but different n-3 HUFA (2.1%, 3.1% or 4.1%) estimated levels from 5 months before and during the spawning period. The diet with an intermediate n-3 HUFA level resulted in a significantly higher ( P <0.05) percentage of buoyant eggs (68.2 ± 2.9%), fertilization (92.8 ± 3.9%), normal cell cleavages (93.5 ± 1.9%), hatching rate (87.7 ± 4.1%) and normal larvae (76.3 ± 3.7%) compared with the other two diets. In contrast, high levels of n-3 HUFA produced larvae with a higher survival capacity when subjected to fasting. The diet with the lowest content of n-3 HUFA produces lower quality eggs and larvae. The n-3 HUFA level in eggs increased with an increase in the dietary level, and the n-3/n-6 ratios were 1:1, 2:1 and 3:1. The DHA/EPA and EPA/ARA ratios of 2 and 4 in eggs, respectively, were associated with improved egg and larval quality and were similar to the ratios found in eggs from wild broodstock. Attainment of optimal fatty acid contents in broodstock diets is one of the key factors for producing the high-quality spawning required for managed culture of this flounder.  相似文献   

6.
Feeding experiments and laboratory analyses were conducted to establish the essential fatty acid (EFA) requirement of red drum (Sciaenops ocellatus). Juvenile red drum were maintained in aquaria containing brackish water (5 ± 2‰ total dissolved solids) for two 6-week experiments. Semipurified diets contained a total of 70% lipid consisting of different combinations of tristearin [predominantly 18:0] and the following fatty acid ethyl esters: oleate, linoleate, linolenate, and a mixture of highly unsaturated fatty acids (HUFA) containing approximately 60% eicosapentaenoate plus docosahexaenoate. EFA-deficient diets (containing only tristearin or oleate) rapidly reduced fish growth and feed efficiency, and increased mortality. Fin erosion and a “shock syndrome” also occurred in association with EFA deficiency. Of the diets containing fatty acid ethyl esters, those with 0.5–1% (n-3) HUFA (0.3–0.6% eicosapentaenoate plus docosahexaenoate) promoted the best growth, survival, and feed efficiency; however, the control diet containing 7% menhaden fish oil provided the best performance. Excess (n-3) HUFA suppressed fish weight gain; suppression became evident at 1.5% (n-3) HUFA, and was pronounced at 2.5%. Fatty acid compositions of whole-body, muscle and liver tissues from red drum fed the various diets generally reflected dietary fatty acids, but modifications of these patterns also were evident. Levels of saturated fatty acids appeared to be regulated independent of diet. In fish fed EFA-deficient diets (containing only tristearin or oleate), monoenes increased and (n-3) HUFA were preferentially conserved in polar lipid fractions. Eicosatrienoic acid [20:3(n-9)] was not elevated in EFA-deficient red drum, apparently due to their limited ability to transform fatty acids. Red drum exhibited some limited ability to elongate and desaturate linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)]; however, metabolism of 18:3(n-3) did not generally result in increased tissue levels of (n-3) HUFA. Based on these responses, the red drum required approximately 0.5% (n-3) HUFA in the diet (approximately 7% of dietary lipid) for proper growth and health.  相似文献   

7.
Abstract— The purpose of this study was to examine the effect of varying dietary levels of highly unsaturated fatty acids (HUFA) in Live prey on the standard length, specific growth rate, survival, and fatty acid composition of yellowtail snapper Ocyurus chrysurus larvae. Two experiments were conducted utilizing rotifers and Artemiu enriched with live algae ( Isochrysis galbana or Nannochloris oculata ) or commercial preparations (Aquagrow Advantage, Aquagrow Advantage plus Aquagrow arachidonic acid, and Algarnac 2000). Larval growth and fatty acid composition were evaluated during the rotifer, B rachionus plicatilis , and Artemia feeding periods and survival rates were calculated at the termination of each trial (18 or 20 d after hatching). In general, prey enriched with the commercial products contained higher levels of docosahexaenoic acid, eicosapentaenoic acid, n-3 HUFA, and × HUFA than those enriched with live algae. The addition of arachidonic acid to the Aquagrow Advantage enrichment medium significantly increased the amount of this fatty acid in rotifers but not in Artemia . At the end of the growth trials, larval standard length was highest when larvae were fed prey enriched with I. galbanu (6.4 mm) or commercial preparations (6.7–7.1 mm) versus N. oculatu (5.2 mm). Furthermore, larvae fed prey enriched with commercial preparations had significantly ( P < 0.05) higher survival rates (2.2-5.9%) than those fed prey enriched with live algae (1.1-1.4%). These results suggest that yellowtail snapper larvae require dietary levels of HUFA beyond those achieved by enriching prey with live N. oculata or I. galbana  相似文献   

8.
牙鲆幼鱼对EPA和DHA的营养需求   总被引：5，自引：2，他引：5  
薛敏 《水产学报》2004,28(3):285-291
研究了EPA和DHA水平对牙鲆生长的影响,饲料中含0.5%EPA和1.0%～1.5%DHA能保证牙鲆幼鱼最适生长,鱼体水分最低,肝体指数最小,脂肪含量有较大幅度提高,肝脏极性脂中EPA和DHA达到最大积累;在肝脏和肌肉的非极性脂部分,各组间的脂肪酸组成没有显著变化,而极性脂部分能体现出饲料中n-3 HUFA含量对鱼体脂肪酸组成的影响,极性脂中的EPA和DHA含量远高于非极性脂;在肌肉和肝脏的极性脂和非极性脂中都含有较高的16:0和18:1n-9; 18:1n-9/n-3HUFA可以作为必需脂肪酸满足程度的一个判据,18:1n-9值的升高往往是缺乏必需脂肪酸的表现,在生长最佳时18:1n-9/n-3HUFA比值下降,为0.62和0.74.  相似文献   

9.
Two experiments were carried out to investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA) levels in rotifers (Brachionus plicatilis) and Artemia on the survival, development and metamorphosis of mud crab Scylla paramamosain larvae. Five different lipid emulsions, varying in the level of total n‐3 and n‐6 highly unsaturated fatty acids (HUFA), DHA, EPA and ARA were used to manipulate the fatty acid profile of the live food. Fatty acid profiles of the live food and crab larvae at zoea one, three and five stages were analysed to study the HUFA uptake by the larvae. The fatty acid content of the live food affected the fatty acid profiles of the crab larvae. In both experiments, the survival rate in the zoeal stages was not statistically different among treatments. However, larval development rate and metamorphosis success were affected by the dietary treatments. In this respect, the DHA/EPA ratio in the live food seems to be a key factor. Enrichment emulsions with a very high (50%) total HUFA content but a low DHA/EPA ratio (0.6), or zero total HUFA content caused developmental retardation and/or metamorphosis failure. An emulsion with a moderate total HUFA (30%) and a high DHA/EPA ratio (4) was the best in terms of larval development during the zoeal stages and resulted in improved metamorphosis. Dietary ARA seemed to improve first metamorphosis, but its exact role needs further clarification. For the larval rearing of S. paramamosain, an enrichment medium containing about 30% total n‐3 HUFA with a minimum DHA/EPA ratio of 1 is recommended. Further investigation is needed on the total HUFA and optimum DHA/EPA ratio requirements for each crab larval stage.  相似文献   

10.
A docosahexaenoic acid (DHA), 22:6(n-3), rich strain of Schizochytrium sp. was used in a spray-dried form to evaluate the enhancement of highly unsaturated fatty acids (HUFAs) in Artemia franciscana nauplii (Utah biotype) and the rotifer Brachionus plicatilis . This heterotrophic microalga was selected because of its high concentration of the longest chain HUFAs in the n-3 and n-6 series, DHA and docosapentaenoic acid (DPA), 22:5(n-6), respectively. When 24-h-old Artemia nauplii were fed 400 mg/L of the algae for 24 h, the DHA content of the nauplii went from undetectable levels to 0.8% of dry weight and the omega-3 HUFA eicosapentaenoic acid (EPA), 20:5n-3, content went from 0.1% to 0.5% of dry weight in the nauplii. Similarly, 22:5(n-6) increased in the nauplii from undetectable levels to 0.4% of dry weight, with a concomitant increase in arachidonic acid, (20:4n-6), from trace to 0.3% of dry weight even though there was no arachidonic acid in the algal biomass. Similar enrichment patterns were observed in rotifers. The results suggest that spray-dried cells of Schizochytrium sp. are effective in enriching Artemia naupli and rotifers in both n-3 and n-6 HUFAs. The results also suggest that Artemia nauplii and rotifers are capable of readily retroconverting 22:6(n-3) to 20:5(n-3) and 22:5(n-6) to 20:4(n-6) through the process of β-oxidation, a well-known process in mammals.  相似文献   

11.
European sea bass juveniles (14.4±0.1 g mean weight) were fed diets containing different levels of fish oil then of n-3 highly unsaturated fatty acids (n-3 HUFA) for 12 weeks. The fish performance as well as fatty acid (FA) composition of neutral and polar lipids from whole body after 7 and 12 weeks feeding were studied. The requirements of juvenile sea bass for n-3 highly unsaturated fatty acids (n-3 HUFA) were studied by feeding fish diets containing six different levels of n-3 HUFA ranging from 0.2% to 1.9% of the diet, with approximately the same DHA/EPA ratio (1.5:1).

The growth rate at the end of the trial showed significant differences. Fish fed low dietary n-3 HUFA (0.2% DM of the diet) showed significantly lower growth than the diet 3 (0.7%), then no further improvement (P>0.05) of growth performance was seen by elevating the n-3 HUFA level in the diet up to 1.9% (diet 6). No difference in feed efficiency, protein efficiency ratio or protein retention was observed among treatments, nor in protein and total lipid content. However, the n-3 HUFA levels in diets highly influenced fish fatty acid composition in neutral lipid, while polar lipid composition was less affected. Comparison of polar lipid content after 7 or 12 weeks indicated that DHA remained stable at the requirement level, while arachidonic acid decreased with time. Results of this experiment suggest that the requirement for growth of n-3 HUFA of juvenile sea bass of 14 g weight is at least 0.7% of the dry diet.  相似文献   


12.
Live hatchery feeds were assayed for fatty acids (FA), amino acids (AA), and their ability to support growth and survival of larval and postlarval mahimahi Coryphaena hippurus at two different hatchery stages. Euterpina acuritrons copepods (C), mahimahi yolk-sac larvae (YSL), Artemia parthenogenica brine shrimp nauplii (BSn), A. parthenogenica juveniles (BSj), and Brachionus plicatilis rotifers (R) were assayed, using several enrichment media. There was little difference in AAs among feeds.
Levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were about 10 times higher in YSL than in their feeds. This explains previous findings where first stage larval survival (0–9 days) was not affected by feed HUFA levels. Second stage survival was significantly higher when larvae were fed copepods. Enrichment with 100 ppm SuperSelco greatly improved the survival of larvae that were fed brine shrimp. The even higher omega-3 fatty acids found in copepods appear to be important for survival of larvae under more stressful conditions.
Brine shrimp juveniles enriched with SuperSelco are a good food for postlarval mahimahi. Yolksac larvae of mahimahi are an even better food, promoting faster growth at less cost, for large scale mahimahi aquaculturists. Different batches of yolksac mahimahi larvae varied by a factor of 10 in their concentration of DHA, but always had the highest level of DHA as much as 40% of total fatty acids (FAs). These "high HUFA" batches of YSL also had the highest levels of EPA and total fatty acids. The data suggest that climate and broodstock age may have considerable influence on larval nutrition.  相似文献   

13.
Abstract— Most marine fish larviculture is dependent on the culture and nutritional manipulation of live prey, of which the rotifers Brachionus sp. are one of the most commonly used. The particular reproductive characteristics of gilthead seabream Spus aurata L. lead to an egg overproduction in commercial hatcheries, where the excess is normally wasted. This study was developed with the objective of testing seabream eggs as an enrichment product for Brachionus sp., using as control the commercial product Algamac 2000×. In view of the need to preserve and store the eggs produced in excess, freezedrying was examined as a possible technical solution for this purpose. The fatty acid profiles of the tested enrichment products (fresh seabream eggs, freeze-dried eggs and Algamac 2000×), as well as of the enriched rotifers at 0 h and after 3,6,12, 15, 18 and 24 h of enrichment, were analyzed. Freeze-dried eggs were stored for 14 and 58 wk prior to analysis, in order to examine a potential deterioration of the fatty acid nutritional quality. A potential use of seabream eggs as an enrichment product for Brachionus sp. was demonstrated. Rotifers enriched with eggs, fresh and freeze-dried, presented relatively high levels of polyunsaturated fatty acids (PUFA), highly unsaturated fatty acids (HUFA; × C20 and 2 double bonds), and fatty acid methyl esters (FAME), a docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio of about 2 and a fairly high (n-3)/(n-6) ratio, especially during the first 3-6 h of enrichment. When freeze-dried eggs were stored in a dry atmosphere during 14 and 58 wk, only a slight and nonsignificant decrease was noted in the fatty acid content over this period of time. Therefore, freeze-drying may be an effective way of preserving the eggs in excess, at least up to 58 wk of storage.  相似文献   

14.
The proliferation of bacteria in intensive aquaculture systems may be responsible for poor growth and mass mortality of marine fish larvae. Essential fatty acids provided in the diet could protect larvae by modulation of the immune response via arachidonic acid (AA) and eicosapentaenoic acid (EPA). Winter flounder Pseudopleuronectes americanus larvae were fed rotifers Brachionus plicatilis enriched with three commercial diets containing different fatty acid profiles. Bacterial colonization on the gills and skin and in the intestinal lumen was evaluated at the end of the rotifer feeding period (day 26), and growth was surveyed until metamorphosis. At 26 days post hatching, larvae fed rotifers containing the higher AA content and with a higher docosahexaenoic acid (DHA) to EPA ratio showed better growth and the lowest bacterial colonization of the intestinal lumen compared to larvae fed rotifers with the lowest AA and DHA : EPA levels. AA had been selectively incorporated into the polar lipids of larvae fed the rotifers enriched with the three diets. This is the first study in winter flounder larvae to report a link between different commercial rotifer enrichments and bacterial density in intestinal lumen.  相似文献   

15.
采用乳化油直接添加法,用n－3高度不饱和脂肪酸（n－3HUFA）含量不等的4种乳化油分别强化轮虫、卤虫活饵料,培育4组黑鲷仔鱼和稚鱼,各自历时15d,结果表明,n－3HUFA对黑鲷仔鱼和稚鱼的生长和存活均有重要影响。在该条件下,轮虫体内n－3HUFA含量为0．233％（湿重计）,卤虫体内n－3HUFA含量为4．273％（湿重计）时,仔鱼和稚鱼达到最佳生长和成活率。  相似文献   

16.
锯缘青蟹幼体饵料的营养强化   总被引：15，自引：0，他引：15       下载免费PDF全文
翁幼竹 《水产学报》2001,25(3):227-231
用酵母、水球藻、鱼油强化和豆油强化四种不同方式培养轮虫，再分别投喂锯缘青蟹幼体，分析测定轮虫和体的生化组成，结果显示，（1）不同方式培养的轮虫之间以及摄食这些轮虫的锯缘青蟹幼体之间的蛋白质含量都没有显著差异；（2）轮虫的脂类含量和脂肪酸组成与培养方式密切相关，小球藻轮虫的脂类含量最高，20：5n-3(EPA)占总脂肪酸的比例也最高 ，为18.05%，鱼油轮虫则含有最多的22：6n-3(DHA)，占总脂肪酸3.16%，脂类含量仅次于小球藻轮虫；（3）锯缘青蟹幼体的脂类含量和脂肪酸组成受相应饵料营养成分的影响。另外，幼体培育实验也发现，饵料营养成分影响幼体的存活率，结果表明，提高轮虫的EPA和DHA含量，尤其晨DHA含量，将有利于锯缘青蟹幼体的存活和发育。  相似文献   

17.
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   

18.
Several commercial oils of plant and animal origin were tested in order to improve the HUFA content and the DHA:EPA ratio of Artemia sp. metanauplii. The relationship between the n-3 and n-6 fatty acid series, and more recently, the DHA:EPA ratio seem to be indicators for better survival and growth of marine fish larvae. The tested plant oils were derived from linseed, peanut and sunflower, and the animal oils came from squid, sardine, cod liver and Selco emulsion. For each oil emulsion tested, four different enrichment periods (9, 24, 33 and 48 h) were evaluated in the same Artemia sp. strain (Artemia EG from Artemia Systems Inc., Baasrode, Belgium). The results show that oil emulsions of plant origin give very poor results in relation to either HUFA content or DHA:EPA ratio. All the oil emulsions from animal origin resulted in HUFA incorporation. Sardine oil was the poorest and squid oil the best. The HUFA content and the DHA:EPA ratio increased with enrichment periods up to 33 h, followed by a negligible variation up to the final 48 h.  相似文献   

19.
Lipid classes and fatty acid levels were analyzed in freshly fertilized eggs, early and late embryo development, and freshly hatched larvae obtained from wild and captive silverside Chirostoma estor estor broodstock, as well as in plankton, Artemia, and pelleted feed. The concentration of triglycerides (TGs) and highly unsaturated fatty acids (HUFAs) in neutral lipid fraction significantly decreased during early development and especially after hatching, whereas phospholipids and HUFA in polar lipid fraction remained constant. These results indicate that TGs rather than PLs are used as energy sources and that all HUFAs [20:4n-6/arachidonic acid (ARA), 20:5n-3/eicosapentaenoic acid (EPA), and 22:6n-3/docosahexaenoic acid (DHA)] of polar lipids are selectively conserved during early development. High levels of DHA (30%, on average, of total fatty acids) and low levels of EPA (4%) were observed in eggs, embryos, and larvae and did not reflect the proportions of these fatty acids in food. Preferential accumulation of DHA from food consumed by broodstock, and then transference to eggs, was probably occurring. The main difference between eggs from both origins was a low level of ARA in eggs from captive fish (4% of total fatty acids) compared to wild fish (9%). This could be associated with a deficiency in the diet that is not compensated for by desaturation/elongation of 18:2n-6 and, possibly, with greater stress in captive fish. In any case, particular requirements of ARA should be determined to optimize the culture of C. estor.  相似文献   

20.
The role of dietary ratios of docosahexaenoic acid (DHA, 22:6n−3), eicosapentaenoic acid (EPA, 20:5n−3) and arachidonic acid (AA, 20:4n−6) on early growth, survival, lipid composition, and pigmentation of yellowtail flounder was studied. Rotifers were enriched with lipid emulsions containing high DHA (43.3% of total fatty acids), DHA+EPA (37.4% and 14.2%, respectively), DHA+AA (36.0% and 8.9%), or a control emulsion containing only olive oil (no DHA, EPA, or AA). Larvae were fed differently enriched rotifers for 4 weeks post-hatch. At week 4, yellowtail larvae fed the high DHA diet were significantly larger (9.7±0.2 mm, P<0.05) and had higher survival (22.1±0.4%), while larvae fed the control diet were significantly smaller (7.3±0.2 mm, P<0.05) and showed lower survival (5.2±1.9%). Larval lipid class and fatty acid profiles differed significantly among treatments with larvae fed high polyunsaturated fatty acid (PUFA) diets having higher relative amounts of triacylglycerols (18–21% of total lipid) than larvae in the control diet (11%). Larval fatty acids reflected dietary levels of DHA, EPA and AA while larvae fed the control diet had reduced amounts of monounsaturated fatty acids (MUFA) and increased levels of PUFA relative to dietary levels. A strong relationship was observed between the DHA/EPA ratio in the diet and larval size (r2=0.75, P=0.005) and survival (r2=0.86, P=0.001). Following metamorphosis, the incidence of malpigmentation was higher in the DHA+AA diet (92%) than in all other treatments (50%). Results suggest that yellowtail larvae require a high level of dietary DHA for maximal growth and survival while diets containing elevated AA exert negative effects on larval pigmentation.  相似文献   

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