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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.
Results from three larval Senegalese sole (Solea senegalensis) feeding trials using non-enriched Artemia and Artemia enriched with Super HUFA®, Arasco®, sunflower oil and microalgae are presented and the effects on larval survival, growth and fatty acid (FA) composition are reported. The FA profile of Senegalese sole eggs was analysed to gather information about the nutritional requirements of the early larval stages and a quite high DHA/EPA ratio (4.3) was found. However, there was no evidence of a high dietary demand for DHA or EPA, given that no relationship was found between dietary HUFA concentration and larval growth and survival. When larvae were fed non-enriched Artemia a significantly better growth and comparable survival were obtained than with Artemia enriched with Super HUFA® (containing the highest HUFA level and DHA/EPA ratio). The FA profiles of the larvae generally reflected those of their diets. DHA was an exception, as it was present in high proportions, even in larvae fed DHA-deficient prey. Total FAME concentration decreased during larval development, with SFA, MUFA and PUFA being equally consumed; HUFA appeared to be less used, with its relative concentration being either kept constant (particularly EPA and ARA) or increased (DHA). A specific requirement for ARA in the first larval stages could not be confirmed but it was always present in considerable amounts, even in larvae fed an ARA poor diet.  相似文献   

3.
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   

4.
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   

5.
《水生生物资源》1999,12(1):31-36
Larvae of the coral reef damselfish Acanthochromis polyacanthus (Bleeker) were fed either unenriched Artemia nauplii or nauplii which had been enriched by pre-feeding with microcapsules containing either squid oil (SQO) or cod liver oil (CLO). Enriched nauplii contained elevated levels of the n-3 highly unsaturated fatty acids (HUFA) eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) which made up 5.22 ± 0.34 and 2.62 ± 0.28 %, respectively, of total fatty acids in nauplii enriched with CLO, and 10.48 ± 0.36 and 3.43 ± 0.33 %, respectively, in nauplii enriched with SQO. In contrast, unenriched nauplii contained EPA (5.03 ± 1.04 %) but did not contain DHA. Survival differed significantly between treatments over the 18-d study; larvae receiving CLO enriched nauplii showed 100 % survival and those receiving SQO enriched nauplii showed 93.3 ± 6.6 % survival. In contrast, only 46 ± 6.7 % of larvae receiving unenriched nauplii survived to the end of the 18-d study. Wet weight, dry weight and proximate biochemical composition did not differ significantly between treatments at the end of the study. Mean standard length of larvae fed CLO enriched nauplii was significantly smaller than that of larvae fed SQO enriched nauplii; however, neither differed significantly from larvae fed unenriched nauplii. The fatty acid composition of A. polyacanthus larvae was significantly influenced by the fatty acid composition of the diet. The results indicate that A. polyacanthus larvae are unable to synthesise DHA from available dietary precursors and, as such, dietary DHA is required to maximise survival. Development of appropriate culture techniques for the larvae of coral reef fishes will allow controlled laboratory studies with these species and may eventually reduce pressure on wild populations exploited for the aquarium trade.  相似文献   

6.
Larval sinking causes larval mass mortality during seed production in the horsehair crab, Erimacrus isenbeckii. Under normal light conditions, horsehair crab larvae generally show negative phototactic behaviour and sink in their rearing seawater. It has been proposed that culturing larvae in the dark may prevent larval sinking. Herein, we examined the effect of photoperiods on horsehair crab larval survival and development to facilitate the development of larval rearing techniques that prevent sinking. Newly hatched larvae were reared with Artemia to the first crab stage in 2‐L beakers under five photoperiods: 0L:24D, 6L:18D, 12L:12D, 18L:6D and 24L:0D. Larvae survived and molted to the first crab stage under all tested photoperiod conditions. The survival rate improved with increasing light period, whereas the developmental period for each larval stage decreased with increasing light period. Longer light periods increased the carapace length at the first crab stage. Our results suggest that larvae could be cultured to the first crab stage in large‐scale tanks under constant darkness. However, significantly improved larval performance under longer photoperiodic conditions indicates a need for developing alternative culture techniques to control larval behaviour in the seed production tank.  相似文献   

7.
The arachidonic acid (20:4n-6,AA) requirements of larval summer flounder weredetermined for the rotifer- and Artemia-feeding stages. Experimental emulsionscontained adequate n-3 highly unsaturated fattyacid (HUFA) ratios and emulsion levels of AAwere set at 0, 3, 6, 9, and 12% (AA0, AA3,AA6, AA9, and AA12). Examination of fatty acidlevels in live feeds and larval tissuesconfirmed the physiological incorporation offatty acids relative to dietary levels. In thefirst experiment, survival, growth, andsalinity tolerance (2-h in 70) were measuredat 18 days after hatch (dah) after feeding thelarvae the various levels of AA. Larvae fedAA6-enriched rotifers were better able tosurvive the salinity tolerance test. AAenrichment up to 12% had no effect on growthand survival. In the second experiment, larvaewere fed AA0- or AA6-enriched rotifers until 23dah, followed by unenriched 24- and 48-h Artemia nauplii until 32 dah. These larvaethen were subdivided and fed AA-enriched Artemia from 33-45 dah. At the end of thisexperiment, larvae fed AA6-enriched rotifershad higher survival, increased growth, andsurvived better in the salinity tolerance test(2-h in 80). The enrichment of Artemiadid not have any effect on these variables.Thus, the provision of AA6-enriched rotifers(10 mg AA g–1 DW) early in larvaldevelopment may serve to enhance larval stresstolerance at the rotifer stage while alsoincreasing larval survival, growth, and stresstolerance later in the Artemia stage.  相似文献   

8.
The effect of different lipid compositions of live feed on the survival, growth rate and pigmentation success of turbot larvae, Scophthalmus maximus (L.), was investigated. Rotifers, Brachionus plicatilis, together with the algae Tetraselmis sp., were administered until day 12, and Artemia was fed until day 27. The experimentally treated live feeds were enriched with four formulated emulsions, resulting in a gradient in the relative contents of 3 HUFA (highly unsaturated fatty acids) and in DHA (docosahexaenoic acid, 22:6 3)/EPA (eicosapentaenoic acid, 20:5 3) ratios in both the rotifers and Artemia.There were no differences in larval growth rate, and only small differences in survival rate throughout the feeding experiment, probably because of satisfactory levels of 3 HUFA in the live feed to sustain growth and survival. A correlation was obtained between the percentage of completely pigmented 27 d old turbot and the DHA/EPA ratio in the total lipids of 12 d old larvae, which again was correlated with the corresponding ratio in the live feed used. The results suggest that normal pigmentation in turbot requires dietary DHA in the early larval feeding period, and that this requirement cannot be replaced by EPA.  相似文献   

9.
A feeding experiment was conducted to evaluate the effect of rotifers (Brachionus plicatilis) and Artemia sp. enriched differently on early growth, survival and lipid class composition of Atlantic cod larvae (Gadus morhua). Rotifers enrichments tested were: (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) a combination of Pavlova sp. paste and AlgaMac 2000®. The same treatments were tested with Artemia as well as a combination of DC DHA Selco® and AlgaMac 2000® as a fourth treatment. After rotifer feeding, the larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw)] were significantly heavier than larvae from treatment 2 (1.03 ± 0.04 mg dw). After feeding Artemia, the larvae from treatment 1 were significantly heavier (12.06 ± 2.54 mg dw) than those from treatments 3 (6.5 ± 0.73 mg dw) and 4 (5.31 ± 1.01 mg dw). Treatment 3 resulted in the best survival through the 59 days of larviculture. After rotifer feeding, high larval concentrations of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA) and ω6 docosapentaenoic acid (ω6DPA) could be linked to better larval growth and survival while after feeding Artemia, high larval DHA/EPA ratios (～3) and high DPA/AA ratios (>1) could be linked to better survival.  相似文献   

10.
The effect of dietary 22:6n-3 (docosahexaenoic acid, DHA) on growth and survival was determined in striped trumpeter during metamorphosis and the Artemia-feeding period (16–36 days posthatch, dph). Artemia were enriched on one of five experimental emulsions that contained graduated concentrations of DHA and constant 20:4n-6 (arachidonic acid, ARA). We also compared larval performance using a commercial enrichment product high in n-3 PUFA. Final DHA concentrations in Artemia enriched on the experimental emulsions ranged from 0.1–20.8 mg/g DM, while Artemia fed the commercial product had 18.2 mg DHA/g DM. Each of the six diets was fed to larvae in four replicate 300-l tanks. Standard length (range 10.0–11.2 mm) and dry weight (range 1.6–2.5 mg) of larvae at the end of the experiment were directly related to dietary DHA, with the highest growth recorded in the experimental diet with the greatest concentration of DHA (20.8 mg/g DM). Survival at 36 dph was not influenced by dietary DHA and ranged from 20–44%. Mortality increased noticeably, regardless of dietary treatment, when larvae attained a standard length of approximately 9.5 mm. Mortality was related to a nocturnal behaviour where larvae would migrate to the tank bottom during the dark phase. Fatty acid profiles of the larvae were generally correlated to dietary fatty acids. Dietary DHA was found to be important in larval striped trumpeter growth, where enhanced growth probably shortened the critical period of metamorphosis and the window where nocturnal downward migration and mortality occurred.  相似文献   

11.
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   

12.
ABSTRACT:   The present study was conducted to investigate the effect of eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) on the survival and the occurrence of molting failure to megalops of mud crab Scylla serrata larvae fed enriched Artemia . Survival rate, intermolt period, carapace width at the first crab stage, ratio of chela to carapace length at the fifth zoeal stage and the occurrence of molting failure to megalops were observed. Mud crab larvae were reared in 1-L plastic beakers and fed with Artemia enriched at five different levels of EPA (0.31% to 1.36% EPA; referred to as E25, E50, E75 and E100) or four different levels of DHA (0.75–0.95% EPA and 0.49–1.38% DHA; referred to as D25, D50, D75 and D100). As a negative control, larvae were fed Artemia enriched with oleic acid (OA). Mud crab larvae fed Artemia containing low (0.41–0.45% EPA and trace DHA) or high (1.36% and 0.95% EPA and 0.16% and 1.38% DHA) amounts of EPA and DHA showed a significantly lower survival rate and prolonged intermolt period ( P  < 0.05). Moreover, a high frequency of molting failure to the megalops stage (34 and 33%) occurs coincident with a high chela to carapace length ratio (43 and 44%) in mud crab larvae fed high amounts of EPA and DHA (E100 and D100), suggesting that both of these treatments contain EPA and DHA in excess. These results indicate that during Artemia feeding, EPA and DHA content should be adjusted to 0.71–0.87% and 0.49–0.72% for maintaining a high survival, accelerating the intermolt period, and producing larger carapace width in the first crab stage.  相似文献   

13.
The larval stage is regarded to be the main bottleneck of halibut production. Halibut eggs were obtained from captive broodstock both by stripping and by natural spawning. Artificial photoperiods were used to increase the total spawning season. Yolk sac larvae are presently produced either in small stagnant units or in large flow through systems. A major consideration is to avoid stress of the larvae, caused by mechanical disturbances of the larvae and by high bacterial load or high ammonia levels in the water.
The experiments showed that halibut larvae began to ingest algae earlier than rotifers Brachionus sp. Supplementation of algae to first feeding tanks resulted in enhanced survival and growth rate of the larvae. Both rotifers and Artemia can be enriched with very high levels of highly unsaturated n-3 fatty acids (n-3 HUFA). Enriched live feed, containing high levels of n-3 HUFA and total lipids, enhanced both survival and growth of the halibut larvae. The highest growth rates were obtained with wild zooplankton and addition of algae, but enriched cultivated feed combined with algae resulted in growth of the same magnitude as with wild zooplankton.  相似文献   

14.
不同饵料对中华绒螯蟹幼体发育和存活的影响   总被引：15，自引：1，他引：15  
江洪波 《水产学报》2000,24(5):442-447
采用高度不饱和脂肪酸（ＨＵＦＡ）营养强化的轮虫、轮虫与卤虫组织投喂中华绒螯蟹幼体,以各项幼体的存活率为评判指标,对不同饵料及其组合的投喂效果进行了探讨。研究结果表明：轮虫是中华绒螯解早期幼体（Ⅰ、Ⅱ期）的适口饵料,幼体存活率随轮虫密度的增加而逐渐上升,但当轮虫数量超过最适密度时,幼体存活率反而有所下降。其中,未强化的轮虫达投喂密度为６０ｉｎｄ．ｍＬ＾－１,强化轮虫最适密度为４０ｉｎｄ．ｍＬ＾－１。Ｚａｏ状Ⅰ、Ⅱ期投喂４０ｉｎｄ．ｍＬ＾－１轮虫,从Ⅲ期开始投喂１０ｉｎｇ．ｍＬ＾－１卤虫无节幼体,能较好地满足中华绒螯蟹幼体发育的营养需求,提高大眼幼体的存活率。表明强化幼体饵料ＨＵＦＡ特别是ＥＰＡ和ＤＨＡ能有效地促进幼体的发育与存活和脱壳率。  相似文献   

15.
The effects of feeding Artemia nauplii enriched with or without poly‐β‐hydroxybutyrate (PHB) and/or highly unsaturated fatty acids (HUFA) on Siberian sturgeon (Acipenser baerii) larvae were investigated. Feeding larvae with PHB‐enriched nauplii (PHB, PHB + HUFA) decreased the growth performance of the larvae. PHB affected the body composition by increasing the lipid content of the whole body and decreasing total saturated, monoenoic, n3, n6 and decosahexanoeic acid (DHA) in the larvae, indicating that the PHB addition affected lipid metabolism. A high activity of pepsin was observed in the digestive extracts of PHB treatments (PHB, PHB + HUFA), while PHB suppressed amylase activity in the intestine of the larvae. Based on molecular analysis, PHB changed the microbial community in the distal intestine of the larvae. The highest counts of goblet cells were observed in the HUFA‐containing treatments (HUFA, PHB + HUFA), indicating that HUFA addition may improve the mucosal barrier defence system. The overall quality of the larvae was evaluated by exposing them to different salinities and ammonia stress levels. PHB decreased survival rates in these challenges. Our results show that optimal PHB doses for bio‐encapsulation into Artemia remain to be determined for further application at the earliest larval stages of sturgeon.  相似文献   

16.
This study aimed to evaluate the effects of enriched Artemia by fish and soybean oils supplemented with vitamin E on growth performance, lipid peroxidation, lipase activity and fatty acid composition of Persian sturgeon (Acipenser persicus) larvae. For this purpose, five experimental diets including non‐enriched Artemia (control diet), Artemia enriched with soybean oil supplemented with 15% and 30% vitamin E (S15 and S30 diets) and fish oil supplemented with 15% and 30% vitamin E (F15 and F30 diets) were used. The larvae were fed to apparent satiation four times per day for 22 days. The results indicated that fish fed enriched Artemia had no significant differences compared with those fed non‐enriched Artemia in terms of growth and survival, but increase in vitamin E levels from 15 to 30% improved growth performance of larvae. Vitamin E content in fish fed S15 and S30 diets was significantly higher. Fish fed non‐enriched Artemia had significantly higher thiobarbituric acid and lower lipase activity. The highest HUFA and n‐3/n‐6 ratio were observed in fish fed F15 and F30 diets. Our results demonstrated that fish oil can completely replace with soybean oil in larval diets. Therefore, using S30 diet is recommended for feeding of Persian sturgeon larvae.  相似文献   

17.
Blue king crab (Paralithodes platypus) larvae were cultivated to test the effects of diet, temperature and rearing density. Dietary treatments included no feeding (unfed), Artemia nauplii enriched with diatoms Thalassiosira nordenskioeldii (THAL), unenriched Artemia fed in addition to Thalassiosira (A+THAL) and a control diet of Artemia enriched with frozen Isochrysis paste (ISO 6). Trials were conducted at 6 °C, and a rearing density of 10 zoea L?1, with six replicates per treatment. The ISO 6 diet was also tested at 3 °C (ISO 3) and 9 °C (ISO 9), and at densities of 20 (ISO 20) and 40 (ISO 40) zoea L?1. Survival of zoea larvae fed the A+THAL diet (91.7%) was significantly higher than all others, whereas unfed zoea larvae died within 2 weeks. Temperature and rearing density had no significant effects on survival. Time required to reach stage C1 was significantly greater at 3 °C (109 days) than at 6 °C (70 days), but did not decrease further at 9 °C. After reaching the postlarval (glaucothoe) stage, half of the replicates in the ISO 20 and ISO 40 treatments were fed continuously, but survival did not differ significantly from unfed glaucothoe. We conclude that blue king crab larvae are not lecithotrophic and can be cultivated with high survival using the proper diet. These techniques can be used to produce large numbers of juvenile crab for laboratory research, or could be modified for use in stock‐enhancement programmes.  相似文献   

18.
Marine fish are generally unable to produce sufficient quantities of n‐3 highly unsaturated fatty acid (n‐3 HUFA) such as eicosapentaenoic acid (EPA; 20:5n‐3) and docosahexaenoic acid (DHA; 22:6n‐3). Consequently, the seed production of marine fish requires careful nutritional enrichment of live feeds such as rotifers and brine shrimp Artemia to meet n‐3 HUFA requirements for normal growth. Another strategy for improving n‐3 HUFA availability is modifying the biosynthetic pathway of marine fish using transgenic technology. In this study, we conducted a feeding trial with non‐transgenic and transgenic nibe croaker Nibea mitsukurii carrying the elongation of very long‐chain fatty acids protein 2 (Elovl2) gene isolated from masu salmon Oncorhynchus masou and three groups of Artemia (non‐enriched and enriched with two products). For all Artemia groups, docosapentaenoic acid (DPA, 22:5n‐3), which is a direct product of Elovl2, was significantly higher in the transgenic fish than that in non‐transgenic fish, despite the absence of DPA in all diets. Thus, applying transgenic techniques to marine fish at the larval stage are a powerful strategy for modifying n‐3 HUFA biosynthetic pathways.  相似文献   

19.
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   

20.
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   

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