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1.
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   

2.
This study evaluated the nutritional value of dietary n‐3 and n‐6 polyunsaturated fatty acids (PUFA) such as linoleic (LOA) and linolenic (LNA) acids, and highly unsaturated fatty acids (HUFA) such as arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids for juvenile Litopenaeus vannamei, based on their effects on growth, survival, and fatty acid composition of hepatopancreas and muscle tissue. Diets contained 5% total lipid. A basal diet contained palmitic and stearic acids each at 2.5% of diet. Five diets contained 0.5% dry weight of LOA, LNA, AA, EPA, or DHA. An additional diet evaluated HUFA in combination by supplementing at 0.5% of diet, a mixture of n‐3 HUFA. All HUFA showed higher nutritional value than PUFA for shrimp and produced significantly (P < 0.05) higher final weight, weight gain, and total lipid in shrimp muscle. Fatty acid profiles of shrimp tissues reflected the composition of the dietary lipids. In general, saturated fatty acids were more abundant in the neutral factions, while PUFA and HUFA were more abundant in the polar fractions of tissues. Under these experimental conditions, HUFA had much greater nutritional value than PUFA for juvenile L. vannamei; moreover, dietary requirements for PUFA were not demonstrated.  相似文献   

3.
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   


4.
Previous results demonstrated the stimulating effect of soybean phosphatidylcholine (PC) on the utilization of dietary neutral lipid in larval and postlarval fish. The present study further investigated the effect of the degree of saturation of dietary PC on the enhancement of dietary fatty acid incorporation in lipids of turbot. Newly-weaned turbot were fed for 20 days on four isolipidic diets containing the same amount of highly unsaturated fatty acids (HUFA), presented either as neutral lipid, i.e. fish oil ethyl esters, or as polar lipid. Diet FO was a phospholipid-free control diet. Diets HPC, SPC and FPC were supplemented with 3% hydrogenated soybean PC, 3% native soybean PC and 3% marine fish roe PC, respectively.The three PC-supplemented diets resulted in better growth and higher muscle triacylglycerol levels than the PC-free diet FO. The fish fatty acids were determined in 3 lipid classes (neutral lipid, PC, phosphatidylethanolamine) of 3 organs or tissues (eye, brain and muscle). Despite the identical amounts of n-6 and n-3 fatty acids provided by the soybean oil and by the HUFA ethyl esters, the substitution of 3% hydrogenated coconut oil in diet FO by 3% hydrogenated PC in diet HPC caused, averaged over the various tissues and lipid classes, a 7 to 12% higher incorporation of 18:2n-6, 20:4n-6, 20:5n-3 and a 32% higher 22:6n-3 level in turbot lipid. Diet HPC appeared as efficient as diet SPC for enhancing the incorporation of the n-3 HUFA from the ethyl esters. Feeding diet FPC, in which the n-3 HUFA were provided through the marine PC source, resulted in slightly higher levels of these fatty acids in the fish than feeding the ethyl ester HUFA diets, even if supplemented with PC. Present results confirm the positive effect of PC, either hydrogenated or native, on the utilization of fatty acids provided in the diet as neutral lipid. The slightly higher incorporation of HUFA, when esterified on dietary PC instead of neutral lipid, raises the question regarding the form of intestinal absorption of PL in fish.p>  相似文献   

5.
A 6‐week feeding trial was conducted to evaluate the nutritional value of dietary linoleic (18:2n‐6, LOA) and linolenic (18:3n‐3, LNA) acids for juvenile Litopenaeus vannamei by determining their effects on growth, survival and fatty acid composition of hepatopancreas and muscle tissue. Diets were formulated to contain 5% total lipid. A basal diet contained only palmitic and stearic acids, each at 2.5% of diet. Six diets contained one of three levels (0.25, 0.5 and 1%) of either LOA or LNA, and three diets had different ratios of LNA/LOA (1, 3, 9) at a combined inclusion level of 0.5% of diet. An additional diet contained 0.5% of a mixture of n‐3 highly unsaturated fatty acids (HUFA). The fatty acid profile of hepatopancreas and muscle of shrimp reflected the profile of the diets. HUFA of the n‐3 family showed higher nutritional value than LOA or LNA for juvenile L. vannamei by producing significantly (P < 0.05) higher final weight and weight gain. Neither LOA nor LNA, alone or in combination, improved growth significantly compared with shrimp fed the basal diet.Thus, dietary requirements for LOA and LNA were not demonstrated under these experimental conditions.  相似文献   

6.
The aim of the present study was to determine the combined effect of both stress and EFA deficiency on several biological and biochemical parameters. Fish were fed during 15 weeks two isocaloric and isoproteic diets: a control diet based on fish oil and formulated to meet the n-3 HUFA requirements for this species (1.5% of n-3 HUFA) and a deficient diet containing beef tallow and formulated to be deficient in n-3 HUFA. Each experimental diet was evaluated both at high and low stocking densities (10 and 3.2 kg m–3 of initial density, respectively).High stocking density produced a chronic stress situation with elevation of plasma cortisol levels. It also caused a reduction in hepatosomatic index and liver lipid contents, increasing the oleic acid/n-3 HUFA ratios in the polar lipids. Fish fed the EFA deficient diet at low stocking density showed common deficiency symptoms. High stocking density in fish fed the EFA deficient diet induced a higher degree of EFA deficiency symptoms leading to mortality, liver steatosis, liver lipid deposition, reduced muscle lipid and reduced n-3 HUFA contents, which particularly affected EPA, but not DHA, suggesting a preferential retention of the latter fatty acid, specially in the phosphoglycerides fraction.  相似文献   

7.
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   

8.
Two 40-day feeding trials using extruded diets were conducted to assess the effect of a dietary phospholipid (PL) supplementation on growth, survival and fatty acid composition of European sea bass (Dicentrarchus labrax) and turbot (Scophthalmus maximus) from weaning onwards. Two dietary treatments (FO and PL) were tested; both had an identical extruded basis (92.5% total diet weight) coated with a different lipid fraction (7.5% total diet weight). Diet PL contained 2% egg yolk PL (69% pure). In diet FO the PL was replaced by hydrogenated coconut oil. The isolipidic diets contained an equal amount of fish oil ethyl esters providing 1.6% (% diet dry weight) of n-3 highly unsaturated fatty acids (HUFA). A diet water stability test showed no effect of the PL supplementation on the leaching of the dietary fatty acids. In both fish species weight, but not survival, significantly increased as a result of PL supplementation. Weaning onto the experimental diets resulted in similar changes in the relative percent levels of fatty acids in both species. In general, the percentage of saturated fatty acids levelled off after a rapid increase, while monoenes increased after an initial decrease. Total n-3 polyunsaturated fatty acids (PUFA) decreased and total n-6 PUFA remained almost constant. The major effect of the dietary PL on fish fatty acid composition was a 50% increase in n-6 and n-3 HUFAs compared to the PL-free FO diet. The rise in n-6 HUFA may have reflected the higher moiety in the dietary PL. On the other hand this was not the case for the n-3 HUFA since they represented only low levels in the PL fraction (0.1%) compared to that provided by the ethyl esters (1.6%) suggesting a more efficient incorporation of the PL n-3 HUFA than of the ethyl ester n-3 HUFA. A second hypothesis is that the dietary PL may have favored the incorporation of the dietary ethyl ester n-3 HUFA.  相似文献   

9.
Dietary supplementation of phospholipids seems to be extremely important to promote growth and survival in fish larvae. Several studies also suggest the importance of n-3 highly unsaturated fatty acids (HUFA) rich phospholipids to further enhance larval performance. In the present study, four different diets were formulated in order to compare the effect of total dietary polar lipid contents, of soya bean lecithin supplementation and of feeding n-3 HUFA in the form of neutral or polar lipids on ingestion and incorporation of labelled fatty acids in gilthead seabream larvae. These diets were prepared including radiolabelled fatty acids from palmitoyl phosphatidylcholine, glycerol trioleate, free oleic acid (FOA) and free eicosapentaenoic acid (FEPA) and were fed to 25 day-old larvae. The results of these experiments showed that the elevation of the dietary polar lipid levels significantly improved microdiet ingestion, regardless of the origins of the polar lipids. This effect caused an improved incorporation of phosphatidylcholine fatty acids to the larval polar and total lipids (TL) as the dietary polar lipids increased. Nevertheless, a better incorporation of fatty acids from dietary polar lipids in comparison with that of fatty acids from dietary triglycerides into larval lipids was found in gilthead seabream, whereas a better utilization of dietary triglycerides fatty acids than dietary free fatty acids could also be observed. Besides, the presence of n-3 HUFA rich neutral lipids (NL) significanlty increased the absorption efficiency of labelled oleic acid from dietary triglycerides, but the presence of n-3 HUFA rich polar lipids, particularly improved the incorporation of FEPA. This fatty acid was preferentially incorporated into larval polar lipids in comparison with FOA.  相似文献   

10.
Essential fatty acid requirements of cultured marine fish larvae   总被引：14，自引：1，他引：14  
Feeding of marine fish larvae is, in most cases, limited to the administration of two species of live prey. This reduction in the range of food available for the cultured larvae may occasionally lead to nutritional imbalances or deficiencies. A large amount of research has been recently devoted to the study of the essential fatty acid requirements of marine fish larvae. Studies on the biochemical composition of developing eggs and larvae, as well as the comparison of the patterns of loss and conservation during starvation, pointed out the importance of n-3 HUFA and arachidonic acid as essential fatty acids for larvae of marine fish. The biochemical composition of marine fish larvae, in terms of lipid content and fatty acid composition of total and polar lipids, is modified by dietary levels of essential fatty acids. Larval growth, survival and activity have also been reported to be affected by dietary levels of essential fatty acids. In addition, some pathological signs, such as hydrops or abnormal pigmentation, have been related to essential fatty acid deficiency in these fish. Based on these effects, the essential fatty acid requirements of marine larval fish have been reported to range between 0.3 and 55 g kg?1 n-3 HUFA on a dry weight basis, suggesting that quantitative requirements of fish larvae may differ from those of juveniles or adults. But quantitative requirements for larvae of the same species reported by various authors are often contradictory. These differences are discussed in relation to the dietary lipid content, ratio 20:5n-3/22:6n-3 and culture conditions used.  相似文献   

11.
A feeding experiment was carried out on gilthead seabream juveniles to investigate the utilization of dietary n−3 highly unsaturated fatty acids (n−3 HUFA), when presented as methyl esters or as triacylglycerols. Three groups of gilthead seabream juveniles, of an initial mean weight of 62 g, were fed diets containing the same level of n−3 HUFA (about 2% dry weight basis, DWB) but where these essential fatty acids (EFA) were supplied in the form of methyl esters, triacylglycerols or as a mixture of these two chemical forms (diets 1, 2 and 3, respectively). A fourth group of 62-g individuals was fed a diet containing a particularly high level of triacylglycerols of n−3 HUFA (about 5% DWB). After 8 weeks of feeding, the results showed that fish growth, hepatosomatic index, total lipid content, and fatty acid composition of neutral and polar lipids of brain, liver, gills and muscle were not affected by the chemical form of the lipids given in the diet. However, individuals fed the very high level of EFA (diet 4) showed a lower growth rate than the other three groups of fish. In addition, eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3) levels in both neutral and polar lipids from liver, gills and muscle were higher in this group of fish, with the brain fatty acid composition being less affected by dietary regime.  相似文献   

12.
The objective of this experiment was to determine the effects of two levels of vitamin E (100 and 300 mg/kg diet) along with two levels of lipid (9 and 14%) and their interaction on growth performance of Indian white shrimp and consequently to evaluate the fatty acid composition and lipid stability of its muscle tissue during frozen storage. Growth of juvenile Indian white shrimp was not significantly affected by dietary vitamin E and lipid levels. Muscle lipid content of shrimp fed diets with 14% lipid was significantly higher than that of with 9% lipid. Obvious effects of the increase in dietary lipid level on muscle fatty acid composition were significant decrease in proportion of 16:0 and increase in proportion of 20:5n-3. The content of vitamin E concentration in shrimp muscle reflected dietary vitamin E concentration and ranged from 6.68 to 14.8 mg/kg muscle corresponding to two (100 and 300 mg/kg) levels of vitamin E in fish diet, respectively. Subsequently, results showed that by increasing the concentration of vitamin E from 100 to 300 mg/kg in diet, the rate of lipid oxidation in the muscle tissue during frozen storage was reduced and, as a result, caused higher HUFA retention in muscle of shrimp fed diet with high lipid level.  相似文献   

13.
A 60-day feeding experiment was carried out on juvenile Iranian sturgeon (Acipenser persicus) to evaluate the effects of different percentages of canola oil and fish oil containing n-3 highly unsaturated fatty acids (n-3 HUFA) on fish growth and fatty acid composition. The requirement for n-3 HUFA of juvenile Iranian sturgeon (48.4 ± 1.98 g) was studied by feeding the fish with various diets containing six different percentage of n-3 HUFA ranging from 1.56 to 17.25 (% of total fatty acids). Neither the weight gain, feed conversion ratio, condition factor, specific growth rate nor the protein efficiency ratio showed any significant differences between the dietary treatments nor in the body composition of juvenile Iranian sturgeon (P > 0.05); also there were no significant difference with respect to the effect of the dietary treatment (P > 0.05) on the blood parameters, for the content of plasma protein, glucose, cholesterol, and triglyceride. The fatty acid composition of the carcass of the Iranian sturgeon fed with the diets containing various levels of n-3 HUFA was reflected by the dietary fatty acid composition. The content of n-3 HUFA in the fish increased with an increase in dietary n-3 HUFA levels. The results indicate that the dietary n-3 HUFA had no effect on the growth of juvenile Iranian sturgeon.  相似文献   

14.
This study was conducted to confirm the essentiality of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) and to investigate the effects of dietary lipid sources on growth performance, liver, and blood chemistry in juvenile Japanese flounder. Three replicate groups of fish (average weighing 3.0 g) were fed experimental diets containing lauric acid ethyl ester, soybean oil, soybean and linseed oils mixture, and squid liver oil as lipid sources for 13 wk. No significant difference was observed in survival among all groups ( P >0.05). Weight gain, feed efficiency and protein efficiency ratio of fish fed the squid liver oil diet containing high n-3 HUFA level were significantly higher than those of fish fed the other diets ( P 0.05). Saturated and monounsaturated fatty acids of liver polar and neutral lipid fractions in fish fed the diet containing lauric acid tended to increase compared to those of the other groups. Fish fed the diets containing soybean and/or linseed oils, which contained high contents of 18:2n-6 and 18:3n-3, respectively, showed the highest contents of 18:2n-6 and 18:3n-3 in both lipid fractions of the liver ( P 0.05). Significantly higher content of n-3 HUFA was observed in both lipid fractions of the liver from fish fed the diet containing squid liver oil than for fish fed the other diets ( P 0.05). Total cholesterol, glucose, and glutamic-oxaloacetic acid transaminase in plasma were significantly affected by dietary lipids ( P 0.05). Histologically, the liver of fish fed the diet containing squid liver oil had a clear distinction between nuclear and cytoplasm membranes; however, cytoplasm of fish fed the diets containing lauric acid and soybean oil was shrunken, and the hepatic cell outline was indistinguishable. It is concluded that the dietary n-3 HUFA is essential for normal growth, and that the dietary lipid sources affect growth performance, liver cell property, and blood chemistry in juvenile Japanese flounder.  相似文献   

15.
为确定细鳞鲑(Brachymystax lenok)n-3 HUFA需求量以减少鱼油使用和降低养殖成本,研究饲料中不同水平的n-3 HUFA对细鳞鲑的生长性能、体成分和肌肉脂肪酸组成的影响。以脱脂鱼粉、脱脂豆粕、明胶和酪蛋白为主要蛋白源,通过调节饲料中的猪油和浓缩油EPA、DHA水平,使饲料n-3HUFA的含量分别达到0.25%、0.50%、0.75%、1.00%、1.25%、1.50%,配制出6种等氮等能的试验饲料(D 0.25、D 0.50、D 0.75、D1.00、D 1.25和D 1.50),分别投喂细鳞鲑幼鱼(60.0 g±2.8 g)84 d。结果显示:饲料中n-3HUFA不同水平对细鳞鲑成活率和饲料系数没有显著影响,但是显著影响了其末重(FW)、增重率(WGR)和特定生长率(SGR)。随着添加饲料中n-3HUFA水平的升高,FW、WGR和SGR有先升高后下降的趋势,且3者在饲料中n-3HUFA水平为0.75%均最大。随着饲料中n-3 HUFA水平的升高,鱼肌肉18∶1n-9的含量逐渐下降,而22∶6n-3的水平相应升高。结果表明,以WGR为评价指标时,用二次曲线模型推测出细鳞鲑对饲料n-3 HUFA的需求量约为0.69%。  相似文献   

16.
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   

17.
投喂蝇蛆对中国明对虾生长及生化组成的影响   总被引：3，自引：0，他引：3  
在试验生态水槽系统内,研究蝇蛆在日粮中不同配比对中国明对虾幼虾生长及生化组成的影响。以蝇蛆在日粮中的所占比例设计了5个梯度组合,经过35d投喂,对虾体长、体质量、特定生长率和成活率升高,对虾肌肉水解氨基酸的总量及其中的必需氨基酸、呈味氨基酸含量增加;在配合饲料中混合投喂3/8以上的蝇蛆可显著提高中国明对虾幼虾的生长速率(P0.05)。对虾肌肉中∑n-3HU-FA、∑n-6HUFA的相对含量随着蝇蛆投喂量的增加而增加,蝇蛆投喂组的必需脂肪酸相对含量均显著低于对照组,多不饱和脂肪酸显著高于对照组。C22∶6n-3/C18∶2n-6比值显著高于对照组,且随着蝇蛆投喂量的增加比值增加。  相似文献   

18.
A study was conducted to determine the effect of increasing dietary levels of fish oil on vitamin E requirement and their effect on growth performance, liver vitamin E status, and tissue proximate and fatty acid compositions of channel catfish. Basal purified diets (42% protein and 3,800 kcal DE/kg) supplemented with 6, 10, and 14% menhaden fish oil were each supplemented with 50, 100, and 200 mg vitamin E/kg (3 × 3 factorial experiment). Each diet was fed to juvenile channel catfish in three random aquaria to apparent satiation twice daily for 12 weeks. Weight gain, feed intake, and feed efficiency ratio were not affected by dietary levels of fish oil, vitamin E, or their interaction. Survival rate at the end of week 12 was significantly lower for fish fed diets containing 14% fish oil, regardless of vitamin E content. Whole-body moisture significantly decreased and lipid increased when dietary lipid levels were increased to 10 or 14%. Dietary vitamin E levels had no effect on body proximate composition. Lipid content of liver was not influenced by dietary levels of fish oil and vitamin E or their interaction. Hepatosomatic index significantly decreased with increasing lipid levels but was not affected by dietary levels of vitamin E. Liver vitamin E increased with increasing dietary vitamin E but decreased with increasing fish oil levels. Fatty acid composition of whole body and liver reflected that of dietary lipid but was not influenced by dietary levels of vitamin E. Whole-body saturates increased, whereas MUFA decreased with increasing dietary levels of fish oil. Liver saturates were not affected by fish oil levels, but MUFA and n-6 decreased and increased, respectively, with increasing fish oil levels. Total n-3 and n-3 HUFA in both tissues increased with increasing fish oil levels in diets, but liver stored much higher levels of these fatty acids.  相似文献   

19.
Litopenaeus vannamei (Boone) grown in ponds are exposed to salinities of less than 5 g L?1 during inland shrimp culture or to more than 40 g L?1 from evaporation and reduced water exchange in dry, hot climates. However, dietary requirements for shrimp grown in low or high salinities are not well defined, particularly for fatty acids. Feeding shrimp postlarvae with highly unsaturated fatty acids (HUFA) enhances tolerance to acute exposure to low salinity, as a result of better nutritional status, or/and specific effects of HUFA on membrane function and osmoregulation mechanisms. This study analysed the effect of HUFA supplementation (3% vs. 34%) on L. vannamei juveniles reared for 21 days at low (5 g L?1), medium (30 g L?1) and high salinities (50 g L?1). Juveniles grown at 5 g L?1 had lower survival compared with controls (30 g L?1) or shrimp grown at 50 g L?1, but no significant effect on survival was observed as a result of HUFA enrichment. In contrast, growth was significantly lower for shrimp grown at 50 g L?1, but this effect was compensated by the HUFA‐enriched diet. Osmotic pressure in haemolymph was affected by salinity, but not by HUFA enrichment. Shrimp fed HUFA‐enriched diets had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in hepatopancreas and gills. These results demonstrate that growth at high salinities is enhanced with diets containing high HUFA levels, but that HUFA‐enriched diets have no effect on shrimp reared at low salinities.  相似文献   

20.
Despite the interest of meagre (Argyrosomus regius) as a fast‐growing candidate for Mediterranean aquaculture diversification, there is a lack of information on nutrition along larval development. Importance of highly unsaturated fatty acids (HUFA) and the antioxidant vitamins E and vitamin C has not been investigated yet in this species. Six diets with two levels of HUFA (0.4% and 3% dw), two of vitamin E (1500 and 3000 mg kg?1) and two of vitamin C (1800 and 3600 mg kg?1) were fed to 15 dah meagre larvae. Larval growth in total length and dry body weight was significantly lowest in larvae fed diet 0.4/150/180 and showed few lipid droplets in enterocytes and hepatocytes and lower HUFA contents than the initial larvae. Increase in dietary HUFA up to 3%, significantly improved larval growth and lipid absorption and deposition. Besides, among fish fed 3% HUFA, increase in vitamin E and vitamin C significantly improved body weight, as well as total lipid, 22:6n‐3 and n‐3 fatty acids contents in the larvae. Thus, the results showed that 0.4% dietary HUFA is not enough to cover the essential fatty acid requirements of larval meagre and a high HUFA requirement in weaning diets is foreseen for this species. Besides, the results also pointed out the importance of dietary vitamin E and C to protect these essential fatty acids from oxidation, increase their contents in the larvae and promote growth, suggesting high vitamin E and C requirements in meagre larvae (higher than 1500 and 1800 mg kg?1 for vitamin E and vitamin C respectively).  相似文献   

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