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1.
We investigated the effect of high levels of n−3 highly unsaturated fatty acids (n−3 HUFA) in broodstock diet on egg quality and chemical composition of eggs of Japanese flounder. The broodstock were fed diets containing three levels of n−3 HUFA (2.1%, 4.8% or 6.2%) 2 months before and during the spawning period. No significant difference was found for weight gain of broodstock among the treatments. Egg production was highest in fish fed the highest level of n−3 HUFA. However, egg quality parameters, such as percentage of buoyant eggs, hatching rate and percentage of normal larvae, were significantly higher in the group fed the lowest n−3 HUFA diet. The fatty acid composition of eggs was influenced more markedly in the neutral lipid fraction than in the polar lipid fraction by dietary n−3 HUFA levels. Arachidonic acid (AA; 20:4n−6) and egg quality parameters both decreased with increasing dietary n−3 HUFA levels. The results suggest that a high level of n−3 HUFA in broodstock diet negatively affects egg quality of Japanese flounder.  相似文献   

2.
The influence of broodstock dietary lipids on egg quality and egg fatty acid composition throughout the spawning season of gilthead seabream was investigated. For this purpose, the fish were fed for 7 months either a control diet (diet C) or a diet deficient in n−3 highly unsaturated fatty acids (n−3 HUFA) but rich in both oleic (18:1n−9) and linolenic (18:3n−3) acids (diet D). Eggs spawned by both groups of fish were sampled at the beginning, middle and end of the spawning season and the fatty acid composition of their neutral (NL) and polar lipids (PL) determined. In the early season, percentages of fertilized and hatched eggs, relative proportions of NL and PL as well as their fatty acid compositions, were not affected by the lipid composition of the broodstock diet. However, the eggs spawned during the middle and late seasons showed marked differences among the two groups of fish, clearly reflecting the influence of dietary fatty acids. This influence was more evident in the neutral lipid fraction than in the polar lipids. No correlation was found between the number of buoyant eggs and eicosapentaenoic (20:5n−3, EPA), docosahexaenoic (22:6n−3, DHA) fatty acids or total n−3 HUFA contents in egg phospholipids. However, a negative correlation was detected when percentages of fertilized eggs were compared with the levels of 18:1n−9, 18:3n−3 and with the ratio 18:1n−9/n−3 HUFA present in the phospholipids. Our results indicate the importance of maintaining not only the level of n−3 HUFA in egg membrane phospholipids, but also the balance between n−3 HUFA and other fatty acids such as 18:1n−9 and 18:3n−3, in order to obtain a high spawning quality.  相似文献   

3.
A feeding experiment was carried out to determine the effect of a diet lacking n-3 and n-6 highly unsaturated fatty acids (HUFA) on lipid and fatty acid content in intestine and gills of male gilthead seabream (Sparus aurata L.) broodstock at different stages of the reproductive cycle: November (pre-spermatogenesis), March (spermatogenesis), and June (post-spermatogenesis). For this purpose, gilthead seabream broodstock were fed either a control diet (C) or an n-3 and n-6 HUFA-deficient diet (D). The results showed no changes in fatty acid content of polar lipids of intestine and gills from fish fed diet C at different stages of the reproductive cycle. However, significant changes were observed in the fatty acid content of neutral lipids in intestine but not in gills in this group. Thus, between November and March, saturates and n-3 HUFA decreased while monoenes increased. In June, the contents of these fatty acids had returned to their initial values (November). Moreover, in fish fed diet D, the fatty acid content of neutral lipid changed in both intestine and gills. In intestine NL, a decrease in saturates and n-3 HUFA and an increment in monoenes were observed from November to June. In gills, a decrease was also observed in n-3 HUFA from NL along the cycle. Nevertheless, n-6 HUFA content remained unchanged. These results show both tissue specificity in seasonal mobilization of fatty acids linked to reproductive processes and the influence of dietary fatty acids on body composition.  相似文献   

4.
The beneficial effects of feeding n−3 highly unsaturated fatty acids (HUFA ≥ 20 carbon fatty acids with three or more double bonds) to palmetto bass (striped bass × white bass) larvae, 4–30 days of age, were studied using Artemia diets enriched with six n-3HUFA levels. Dietary n-3HUFA concentrations were < 0.03% (control diet), 0.33%, 0.63%, 0.87%, 1.26%, and 2.27% of dry-wt Artemia. Larval n-3HUFA contents were reduced at a faster rate with decreasing dietary n-3HUFA intake, and were significantly different by 30 days posthatch (4–20 mg g−1 dry-wt fish). Starved larvae selectively conserved endogenous n-3HUFA reserves, indicating an essential role of n-3HUFA in larval development. Mass mortality in the control and 0.33% n-3HUFA diets occurred at metamorphosis (26–28 days posthatch). At harvest, all fish, except those fed the two highest n-3HUFA diets, suffered from handling stress (shock syndrome) with increasing severity (25 to 100%) at decreasing dietary n-3HUFA intake. Recovery from shock syndrome was 100% at the 0.63% and 0.87% n-3HUFA diets, 63% at the 0.33% n-3HUFA diet and 0% at the control diet. Post-harvest survival was similar among the four highest dietary n-3HUFA groups (64–73%), whereas the two lowest n-3HUFA groups differed significantly (0 and 37%). Growth promotion was evident with increased dietary n-3HUFA intake as fish fed the highest n-3HUFA diet were twice the size of those fed the control diet (99 vs 52 mg wet-wt). Final fish sizes at the three highest n-3HUFA diets were similar. Given similar culture conditions, a minimum dietary n-3HUFA intake of 1.26% of dry-wt Artermia is recommended to avoid handling stress and promote growth in larval palmetto bass.  相似文献   

5.
Against a background of decreasing availability of fish oils for use in aquaculture, the present study was undertaken to examine whether a wax ester-rich oil derived from the calanoid copepod Calanus finmarchicus, could be used effectively by Atlantic salmon when supplied in their diet. Individually tagged Atlantic salmon of initial weight around 500 g were divided into replicate tanks of two dietary groups and fed either a fish oil supplemented diet, or an experimental diet coated with Calanus oil. Wax esters accounted for 37.5% of the lipids in the Calanus oil diet but were absent from the fish oil diet in which triacylglycerols (TAG) were the major lipid class. Over the feeding period (140 days) the salmon fed fish oil displayed a greater increase in length, but there was no significant difference between the two groups in weight gained. The specific growth rates (0.75) and the feed conversion ratio of fish fed the two diets were similar throughout the study. No differences were observed in the apparent digestibility coefficients (ADC) of fish fed Calanus oil or fish oil. The ADC of fatty acids decreased with chain length and increased with unsaturation. Long-chain alcohol utilization showed a similar tendency although there was a notable difference in that saturated long-chain alcohols were utilized better than the comparable fatty acid homologue. In fecal lipid of fish fed Calanus oil, the content of 16:0 alcohol decreased in both the free long-chain alcohol and wax ester fractions, while the corresponding fatty acid increased in the feces of both dietary groups of fish. In contrast, the proportion of the 22:1n−11 alcohol increased in both fecal wax esters and free long-chain alcohol fractions whereas 22:1n−11 fatty acid displayed no accumulation. The observed patterns of fatty acid and long-chain alcohol compositions in fecal lipid compared to those of the initial dietary lipid are consistent with the digestive lipases of salmon preferentially hydrolyzing esters containing polyunsaturated fatty acid (PUFA) moieties. The wax esters of Calanus oil contained substantial amounts of the n−3 PUFA, 20:5n−3 and 22:6n−3, that were effectively deposited in muscle and liver tissues. No major differences were seen in either lipid content/lipid classes or in gross fatty acid composition of these tissues between the two dietary groups. It is concluded that that Atlantic salmon in seawater can effectively utilize diets in which a major lipid component is derived from zooplankton rich in wax ester without any detrimental change in growth or body lipid composition. This finding gives support to the use of lipid from zooplankton from high latitudes as an alternative or as a supplement to fish oil and a provider of long-chain n−3 PUFA in diets for use in salmon aquaculture.  相似文献   

6.
制备3种基本组成相同、添加不同类型鱼油的微粒饲料。将3种微粒饲料分别投喂真鲷(Pagrus major)仔鱼,探讨了微粒饲料中鱼油n—3HUFA的不同分子结构对真鲷仔、稚鱼生长、存活的影响。25d的养殖试验结果表明,虽然饲料2中n-3HUFA的含量高于饲料1中n—3HUFA的含量,饲料3中n—3HUFA的含量同饲料1中n—3HUFA的含量相等,但是用饲料1投喂的真鲷仔、稚鱼的全长、成活率要优于分别用饲料2和饲料3投喂的真鲷仔、稚鱼的全长、成活率。而且,用饲料1投喂的真鲷仔、稚鱼体内n-3HUFA和DHA的含量高于用饲料2和饲料3投喂的真鲷仔、稚鱼体内n—3HUFA和DHA的含量,这说明真鲷仔、稚鱼对天然鱼油的消化、吸收要优于对乙酯化鱼油的消化、吸收。  相似文献   

7.
A feeding experiment was conducted on gilthead seabream (Sparus aurata) broodstock to investigate the incidence of n-3 highly unsaturated fatty acids (n-3 HUFA) dietary deficiencies on the lipid composition of female liver, gonads and eggs, in relation to spawning quality. Broodstock were fed a control (C) diet or a n-3 HUFA deficient (D) but linolenic acid rich diet. After 20 weeks of feeding, the results showed that levels of total neutral (TNL) and total polar (TPL) lipids of female gonads and eggs were independent of diet. However the fatty acid composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) of female liver, gonads and eggs in the two groups of fish showed marked differences, reflecting the influence of fatty acid levels in the broodstock diets. This influence was even higher in TNL than in the phospholipid classes examined. In fish fed n-3 HUFA deficient diet, fatty acid composition of TNL of female gonads and eggs reflected the diet more than liver. A higher egg production in broodstock fed C diet (1.8% n-3 HUFA in diet) was extended to spawning quality such as percentages of fertilised and hatched eggs.  相似文献   

8.
Total lipid (TL), lipid classes and fatty acid composition of neutral (NL) and polar (PL) lipids were studied in the gonads, liver and muscle of gilthead seabream males ( Sparus aurata ) fed a control diet (diet C) or an n-3 and n-6 highly unsaturated fatty acids (HUFA)-deficient diet (diet D), at different stages of the reproductive cycle. Between pre-spermatogenesis (November) and spermatogenesis (March), the lipid content was high and particularly rich in cholesterol, phosphatidylcholine and phosphatidylethanolamine in gonads from both dietary groups. At post-spermatogenesis (June), TL and especially PL dramatically decreased in the gonads from both groups. However, at this period diet C fish gonads were richer in triacylglycerides (TAG) than those from diet D fish. The liver lipid contents and particularly TAG were over 200% lower in June than in March for both groups. Nevertheless, the most noteworthy depletion of lipids during this period was achieved by the n-3 HUFA in diet D fish. Conversely, arachidonic acid (20:4n-6) did not decrease in NL or PL from gonads and liver in groups C and D. Muscle lipids from diet C fish were relatively insensitive to seasonal influences. However, in June, the muscle TAG content was significantly reduced in diet D fish.  相似文献   

9.
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   


10.
The effect of lipid supplementation and algal ration on growth and fatty acid composition of juvenile clams, Tapes philippinarum was investigated. A diet of Tetraselmis suecica was supplemented with a lipid emulsion and fed at a daily ration of 0.5, 1.0 and 1.5% WW DW−1 day−1. A mixed algal diet of Isochrysis galbana (clone T-Iso) and T. suecica (1:1 on DW basis) and starvation functioned as positive and negative control treatments, respectively. T. suecica, which contains eicosapentaenoic acid (20:5n−3) but no docosahexaenoic acid (22:6n−3), was supplemented with 50% (% of algal dry weight) of a 22:6n−3-rich emulsion. Higher growth rates of T. philippinarum were associated with higher T. suecica feeding rations. Lipid supplementation resulted in significantly better growth rates of T. philippinarum at a T. suecica ration of 0.5, 1.0 and 1.5% WW DW−1 day−1. The growth promoting effect of lipid supplementation was significantly reduced during 4 consecutive weeks or by increasing the algal feeding ration. Increasing T. suecica rations were associated with a decrease in the % composition of 22:6n−3 while the 20:5n−3% composition was hardly affected in the total lipids of T. philippinarum. On the contrary, the absolute concentration of 22:6n−3 (μg per gram dry weight, μg g DW−1) in the total lipids of T. philippinarum was similar at all T. suecica rations while the 20:5n−3 concentration significantly increased. The major effect of lipid supplementation on the fatty acid composition of the clams, was a significant increase of the 22:6n−3% composition in the total lipids, polar lipids and triglycerides. In contrast with 20:5n−3, the effect of lipid supplementation on the absolute 22:6n−3 content (μg g DW−1) was more pronounced at a higher T. suecica ration. After a starvation period of 4 weeks, the concentration (μg g DW−1) of all fatty acids was significantly reduced, except the n−7 monoenoic fatty acids (MUFA) and the non-methylene interrupted dienoic fatty acids (NMID). The concentration (μg g DW−1) of the NMID in starved clams and clams fed different diets was similar to the concentration in the initial sample. This indicated that growing spat was actively synthesising NMID and they were selectively retained in unfed animals. The results indicated that either dietary lipid or 22:6n−3 was a growth-limiting factor when T. suecica was fed at a ration of 0.5, 1 and 1.5% WW DW−1 day−1. A selective retention in starved clams and a preferential accumulation in fed clams was observed for 22:6n−3 but not for 20:5n−3 which indicated a greater importance of 22:6n−3 compared to 20:5n−3.  相似文献   

11.
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   

12.
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   

13.
An experiment was conducted to determine the effect of an essential fatty acid (EFA) deficient diet on growth, immune status and renal morphology of juvenile gilthead sea bream, using two diets: a control diet containing 2% (DW) of n-3 high unsaturated fatty acid (n-3 HUFA) and a diet formulated to be deficient in EFA for this species and containing 0.5% DW of n-3 HUFA (diet NFA). After 9 weeks of feeding the EFA-deficient diet fish showed a reduction in growth compared with the control group (107.48 +/- 9.14 and 123.14 +/-11.87 g final weight respectively). Fish fed the NFA diet showed a reduction in the erythrocyte volume together with increased erythrocyte fragility, haemoglobin content and red blood cell count in comparison with fish fed the control diet. EFA deficiency also reduced cellular immunity in terms of neutrophil activity and the number of circulating lymphocytes. The serum alternative complement pathway was markedly reduced in fish fed the EFA deficient diet. Fish fed the control diet showed glomeruli with a well-defined Bowman's space and normal renal tubes. However, up to 88% of fish fed the EFA-deficient diet showed alterations in renal morphology affecting at least 50% of the glomeruli, which showed extreme dilation of capillaries and occlusion of Bowsman's capsule. Mesangial proliferation and diffuse thickening of the capillary walls, as well as renal tube degeneration, were also observed.  相似文献   

14.
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   

15.
Abstract. Two experiments were carried out to study the effect of n -3 HUFA levels in rotifers on survival, growth, activity and fatty acid composition of gilthead bream, Sparus aurata (L.), larvae. From the third to the 15th day after hatching, gilthead bream larvae received one of the three kinds of rotifers containing different percentages of n –3 HUFA. Moisture, crude lipid, saponifiable matter and fatty acid composition of total lipids of rotifers and larvae were determined.
A good correlation was found between larval growth and n –3 HUFA levels in rotifers. Larval survival was also significantly improved by the elevation of the n –3 HUFA levels in rotifers. A high occurrence of hydrops was registered in larvae fed with EFA-deficient rotifers. The n –3 HUFA levels in the larvae were increased by the elevation of n –3 HUFA contents in rotifers. However, n –9 fatty acids in the larvae remained almost constant, regardless of the different 18:1 n –9 contents in rotifers. Therefore, the ratio of oleic acid to n –3 HUFA, known to be an indicator of the EFA deficiency in fish, was reduced by the elevation of the n –3 HUFA levels in rotifers.  相似文献   

16.
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17.
Recent advances in lipid nutrition in fish larvae   总被引：14，自引：2，他引：14  
Due to the importance of dietary lipid utilization for larval rearing success, increasing attention has been paid during the last years to different aspects of larval lipid nutrition such as digestion, absorption, transport and metabolism, which are frequently studied by different research groups. The present study reviews the published information on these aspects, including some recent results obtained in our laboratory, that contribute to a better understanding of larval lipid nutrition.Neutral lipase activity was found in the digesta of larval gilthead seabream as early as first feeding, followed by a significant increase which reached up 8 times the initial levels at day 15 and was clearly influenced by the fatty acid composition of dietary lipids. Accordingly, the capacity for lipid absorption by the intestinal epithelium has been also observed at the onset of exogenous feeding, although the specific location in the different digestive tract segments differ with species. Whereas the capacity to absorb lipid increases with development in live prey-fed larvae, this improvemment is delayed in larvae fed formulated diet. Increasing dietary phosphatidyl cholines levels enhanced lipid absorption regardless of whether it is of soybean or marine origin, but the latter improved hepatic lipid utilization. Enzymatic, histological and biochemical evidences suggest that marine fish larvae are able to effectively digest and absorb n-3 HUFA-rich triacylglycerols, but feeding with phosphoacylglycerols, particularly if they are rich in n-3 HUFA, would enhance phosphoacylglycerols digestion and specially lipid transport alowing a better n-3 HUFA incorporation into larval membrane lipids and promoting fish growth. Although the essentiality of n-3 HUFA for larval marine fish has been studied extensively, only recently has the importance of dietary arachidonic acid in the larvae of few species been recognised. Evidences for competitive interactions among these essential fatty acids suggest that besides a minimum dietary requirement for each essential fatty acid, their relative ratios must also be considered.  相似文献   

18.
Due to its traditionally good availability, digestibility and high content of n ? 3 HUFA, fish oil is the main lipid source in fish feeds. However, world demand for this product has grown significantly in recent years, whereas its production, based on fisheries landings, is static. The purpose of the present study was to assess the effect of partial replacement of fish oil in compound diets for gilthead seabream and seabass, by several vegetable oil sources, on growth, dietary fatty acid utilization and flesh quality. Five iso‐energetic and isoproteic experimental diets were formulated (25% lipid content). Fish oil was the only added lipid source in the control (FO) diet, and it was included in the other experimental diets at a level high enough (40% of FO diet) to keep the n ? 3 HUFA levels well over 3% in order to cover the essential fatty acid requirements of these species. Fish oil was replaced by soyabean oil (SO), rapeseed oil (RO) and linseed oil (LO) or a mixture (Mix) of them. Feed intake in all dietary groups was in the range of results obtained for commercial diets in both species, and growth and feed utilization were very good. The results show that, providing a minimum content of essential fatty acids in the diet, it is possible to replace up to 60% of the fish oil by SO, LO and RO or a mixture of them in diets for seabream and seabass, without compromising fish growth. Fatty acid composition of liver and muscle reflected that of the diet, but utilization of dietary lipids differed between these two tissues and was also different for the different fatty acids. Despite reduction in dietary saturated fatty acids by the inclusion of vegetable oils, their levels in fish liver were as high as in fish fed the fish oil diet, whereas, in muscle, levels were reduced according to that in the diet. Linoleic and linolenic acids were accumulated in the liver proportionally to their levels in the diet, suggesting a lower oxidation of these fatty acids in comparison to other 18C fatty acids. Regarding eicosapentaenoic acid (20 : 5n ? 3; EPA), docosahexaenoic acid (22 : 6n ? 3; DHA) and arachidonic acid (20 : 4n ? 6; ARA), these essential fatty acids were reduced in the liver at a similar rate, whereas DHA was preferentially retained in the muscle in comparison with the other fatty acids, denoting a higher oxidation particularly of EPA, in the muscle. Some other PUFA increased despite their low dietary levels in seabream fed LO diets and in seabass fed SO diet, suggesting the stimulation of delta‐6 and delta‐5 desaturase activity in marine fish. Despite differences in fatty acid composition, fillet of fish fed vegetable oils was very well accepted by trained judges when assessed cooked.  相似文献   

19.
Atlantic salmon were fed one of four diets with increasing levels (11–58%of total fatty acids (FAs)) of n‐3 highly unsaturated FAs (HUFAs) in order to investigate the effect on muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress. The high n‐3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) groups contained lower percentages of sphingomyelin and cardiolipin in total muscle than the intermediate n‐3 HUFA group. Cardiolipin and sphingomyelin are particularly susceptible to peroxidation, and a reduced percentage of these lipids showed that mitochondrial membranes had been damaged by oxidation. The intermediate n‐3 HUFA group had the highest level of mitochondrial integrity and tendencies of lower thiobarbituric acid reactive substances (TBARS) level than the other dietary groups. The high caspase‐3 activity, in addition to casp3a and bax gene expression levels, in the n‐3 DHA group also suggests that some degree of oxidative stress had occurred. Electron microscopy images showed a higher degree of myofibre–myofibre detachment in fish fed the high HUFA diets than in fish fed the intermediate n‐3 HUFA diet. Our findings show that intermediate levels of n‐3 HUFAs in salmon diets gave the best protection against oxidative damage of mitochondrial membranes and muscle structure.  相似文献   

20.
The rotifer Brachionus plicatilis (S-type Hawaiian strain) was cultured with various combinations of baker's yeast and Nannochloropsis oculata. There were no significant differences in the daily rotifer production and amino acid profiles of the resulting rotifers. The significantly lower levels of fatty acids (C14, C16, C20:4n−6, C20:5n−3 and C22:6n−3) observed in the rotifers were found to correspond with the amount of yeast presented in their diet. The low survival and growth of striped mullet larvae recorded at Day 15 posthatching indicates that rotifers fed only yeast were nutritionally deficient in fatty acids. The fatty acid requirements of mullet, however, appeared to be satisfied with rotifers cultured on a combination of yeast and N. oculata. In contrast, no significant differences in larval milkfish survival and growth at Day 10 posthatching were detected when using rotifers fed the various diets in the larval rearing protocol.  相似文献   

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