Influence of dry diets on reproductive performance and egg lipid composition during the first spawning season of captive pollack

Four‐year‐old pollack Pollachius pollachius L., previously fed on dry pellets since their juvenile stage, were divided into three experimental groups two months prior their first spawning season. They were fed a commercial broodstock pellet enriched with 6% added oils, either: (1) capelin oil (control), (2) capelin oil plus arachidonic acid, or (3) DHA rich tuna oil. Spawning performance was determined in each group and egg lipids were analysed. During the vitellogenic period, the estradiol levels in plasma increased with oocyte enlargement, indicating that captivity and pelleted feed did not affect reproductive capacity. Females from each group spawned spontaneously between February and May. Egg production per kg of female was highest in the control group. Fertilization rate was highest (39%) in the group fed on diet enhanced in DHA. Lipid content in eggs reached 16% of dry mass, containing mainly phospholipids (75%). Egg fatty acid profiles showed few differences between dietary treatments. There was no significant difference in the concentration of Docosahexaenoic acid (22:6n − 3) between groups. Arachidonic acid (20:4n − 6) was lower in neutral and polar lipids of eggs from the control group than in the other groups. Tuna oil diet induced the highest DHA/EPA ratio in eggs and seemed to provide sufficient arachidonic acid for pollack broodstock. Egg fatty acid profiles are compared with 6 year‐old pollack broodstock fed on fish, and with other cultured and wild fish species.     

Is the fatty acid composition of Daphnia galeata determined by the fatty acid composition of the ingested diet?

1. The fatty acid (FA) composition of Daphnia galeata and their algal food was analysed and showed many similarities, however, some significant differences were also found in the relative abundance of the FA C16 : 4ω3 and docosahexaenoic acid (DHA). Their relative abundances were much lower in daphnids than in their algal diet.
2. When daphnids were fed three distinct emulsion particles with DHA : eicosapentaenoic acid (EPA) ratios of c. 0.7, 2 and 4, the final DHA : EPA ratio in the daphnids always favoured EPA. The increase of the food DHA : EPA ratio resulted in a minor increase of DHA (to c. 2%). Feeding the animals on emulsion particles with increasing ratios of DHA : EPA, caused a minor ( c. 2%) increase of DHA level but EPA levels remained high ( c. 10%).
3. When labelled with [¹⁴C]linoleic acid and [¹⁴C]linolenic acid daphnids showed low conversion of both essential FA into C20 polyunsaturated fatty acids (PUFAs). This low conversion activity might explain the importance of C20 PUFAs as dietary compounds in the food of Daphnia.
4. The results indicate the insignificance of DHA and C16 : 4ω3 for daphnids. As EPA can be derived from C18 : 3ω3 it is not strictly essential, although it might be a significant factor in food quality for Daphnia.     

Improvement of nutritional quality of cultured sobaity sea bream,Sparidentex hasta (Valenciennes) muscle by preharvest feeding of finisher feeds

A 6‐month long study was conducted to improve the nutritional quality of the cultured sobaity bream, Sparidentex hasta by feeding them finisher feeds containing high docosahexaenoic acid (DHA) at the last two months of the grow‐out stage so that the muscle DHA level be increased at par to the wild. A grow‐out feed used from the beginning until the end of the trial was considered as the control (Diet 1). Experimental diets 2 and 3 were formulated to contain 9.0% DHA (e.g. 1.68 g DHA/100 g feed) and 10.5% DHA (2.20 g DHA/100 g feed), by incorporating high DHA tuna oil into a sea bream grow‐out diet. For comparison, a commercial finisher feed (Diet 4) from Skretting, Italy was also used. The results of this study demonstrated that fish fed DHA enriched finisher diets resulted in significantly (p < .05) better growth, feed utilization and higher muscle eicosapentaenoic acid (EPA) and DHA content compared to those fed grow‐out diet. The muscle DHA and EPA of fish fed finisher diets were also higher than those of the whole year average DHA and EPA content of wild sobaity. An organoleptic evaluation showed no significant (p > .05) differences between sensory attributes of muscle from cultured and wild sea bream. The results of the study demonstrated that feeding finisher feed enriched with DHA at the later part of the grow‐out operation, the n‐3 PUFA levels of cultured sobaity can cost‐effectively be increased at par to the wild.     

Post‐release growth and dispersal of pond and hatchery‐reared European grayling Thymallus thymallus compared with their wild conspecifics in a small stream

The growth, and dispersal of stocked European grayling Thymallus thymallus, reared in a hatchery (fed dry food pellets) or in a pond (fed natural food), compared with their wild conspecifics was assessed from the recapture of individually tagged fish 168 days after their release into the Blanice River, Czech Republic. Recapture rates and site fidelity were higher for wild T. thymallus than for artificially reared fish. Specific growth rate and upstream or downstream dispersal did not significantly differ between any of the groups of fish. An influence of rearing conditions (pond v. hatchery) on the overall performance of stocked fish was not demonstrated. Initially, lower condition factors of reared T. thymallus were equal to wild fish after recapture, suggesting adaptation of artificially reared fish that remained in the sections studied.     

Fatty acid content of some freshwater fish of commercial importance from tropical lakes in the Ethiopian Rift Valley

Fifty samples of freshwater fish, representing eight tropical species, were collected from Ethiopian Rift Valley lakes in order to study the variation of lipids and fatty acids (FA) both within and between species. Most specimens (36 samples) were low in fat, ≥5% of dry weight (dw). Medium- (nine samples) and high-fat fish (five samples) contained ≤6% and >10% dw, respectively. The extent of variation was more pronounced in the herbivore Oreochromis niloticus than in the omnivorous (e.g. Barbus sp.) or carnivorous–piscivorous ( Clarias gariepinus ) fishes. Twenty-eight FA of various chain lengths and saturation levels were identified. Most FA were unsaturated and long-chained. The major individual FA were palmitic acid (16:0), stearic acid (18 : 0), oleic acid (18 : 1ω9) and docosahexaenoic acid (DHA) (22 : 6ω3). The ω3/ω6 ratio varied considerably (1·1–7·6) and O. niloticus from Lake Haiq was found to be superior in lipid quality to all the tropical fish species considered in this study. The data show that tropical freshwater fish are comparable to temperate freshwater fish as sources of polyunsaturated FA.     

Preferential accumulation of fatty acids in the testis and ovary of cultured and wild sweet smelt Plecoglossus altivelis

The effect of dietary lipid on the fatty acid composition of muscle, testis and ovary of cultured sweet smelt, Plecoglossus altivelis, was investigated and compared with that of wild sweet smelt. Cultured fish were fed three different diets for 12 weeks: a control diet rich in docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) (CO group); a diet deficient in DHA and EPA (DP group); and a diet rich in alpha-linolenic acid (ALA, 18:3n-3), but deficient in DHA and EPA (LP group). The fatty acid composition of muscle and gonad lipids was related with dietary fatty acids. Despite the difference in DHA and EPA content in the diets, muscles and gonads, respectively, contained almost equal levels of DHA and EPA in each CO and DP group. However, the muscle and gonad of the LP group showed a lower level of DHA than other groups, due to having the highest level of ALA. In the wild fish muscle, the DHA content was similar to that of CO and DP groups, but the EPA content showed the highest level in all groups. There was no difference in the muscle fatty acid proportions between male and female. On the other hand, the testes of cultured and wild fish were rich in DHA, EPA, docosapentaenoic acid and arachidonic acid, while ovaries were rich in oleic, palmitoleic, linoleic acids and ALA. Moreover, of all the groups, the fish fatty acid composition of the LP group was closest to that of wild fish. These results indicate that in the sweet smelt, tissue n-3 polyunsaturated fatty acids (PUFAs) greater than C20 can be synthesized from dietary precursors and special fatty acids are preferentially accumulated to the testis or ovary, respectively, to play different physiological functions.     

Towards Integrated Multi-Trophic Aquaculture: Lessons from Caprellids (Crustacea: Amphipoda)

The search for alternative live feed organisms and the progression of Integrative Multi-Trophic Aquaculture (IMTA) are currently being highly prioritised in EU strategies. Caprellids could potentially be an important exploitable resource in aquaculture due to their high levels of beneficial polyunsaturated fatty acids, fast growing nature and widespread distribution. Furthermore, since they are mainly detritivorous, they could be excellent candidates for integration into IMTA systems, potentially benefitting from uneaten feed pellets and faeces released by cultured fish in fish farms and sea-cage structures. Despite this, there is a lack of experimental studies to: (i) test inexpensive diets for caprellids, such as detritus, (ii) develop sustainable caprellid culture techniques and (iii) include caprellids in IMTA systems. The main aim of this study was to determine whether detritus (D) in the form of fish faeces provided an adequate diet for caprellids in comparison to other traditional diets, such as Artemia nauplii (A) or phytoplankton (P). Adult survival rate was shown to be significantly higher for caprellids fed with D. Conversely, hatchlings had the highest survival rate with A, although the juvenile growth rate and number of moults was similar in the three diets. With regard to lipid composition, caprellids fed with A had higher concentrations of Triacylglycerols (TAG) and Phosphatidylcholine (PC) while those fed with P or D were richer in polyunsaturated fatty acids, especially 22:6(n-3) (DHA). Interestingly, caprellids fed with D were also a rich source of 18:2(n-6) (LA), considered to be an essential fatty acid in vertebrates. It was found that detritus based mainly on fish faeces and uneaten feed pellets can be considered an adequate feed for adult caprellids, providing a source of both omega-3 (DHA) and omega-6 (LA) fatty acids. Hatchlings however seem to require an additional input of TAG and PC during juvenile stages to properly grow.     

Effects of fatty acid and phosphorus content of food on the growth, survival and reproduction ofDaphnia

1. Mixtures of microencapsulated lipids and Scenedesmus quadricauda grown at different degrees of P limitation were used as food for Daphnia galeata in two growth experiments. Thereby, food quality in terms of ω3-fatty acid (ω3-FA) or phosphorus (P) content could be assessed without interference from other factors.
2. ω3-highly unsaturated fatty acids (ω3-HUFA), given to Daphnia as fish oil or eicosapentaenoic acid (EPA) together with non P-limited algae, decreased the time to first reproduction. When fed fish oil, somatic growth and survival were also enhanced. Linolenic acid also decreased the time to first reproduction but to a lesser extent than EPA.
3. Food quality depended to a large extent on the degree of P limitation of Scenedesmus , which is consistent with P limitation of Daphnia. The overall impact of P was always larger than the effect of ω3-FA. Growth, survival and reproduction were elevated when Daphnia were fed non P-limited Scenedesmus compared to treatments with P-limited algae.
4. The relative importance of ω3-HUFA and P content in the food changed over a C : P gradient, with stronger effects of ω3-HUFA at low C : P ratios.     

Physiological effects of a fish oil supplement on captive juvenile tuatara (Sphenodon punctatus)

Tuatara (Sphenodon, Order Sphenodontia) are rare New Zealand reptiles whose conservation involves captive breeding. Wild tuatara eat seabirds, which contain high levels of the long-chain n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids are absent from the captive diet, and consequently, plasma fatty acid composition of wild and captive tuatara differs. This study investigated the effects of incorporating EPA and DHA into the diet of captive juvenile tuatara (Sphenodon punctatus) in an attempt to replicate the plasma fatty acid composition of wild tuatara. Tuatara receiving a fish oil supplement containing EPA and DHA showed overall changes in their plasma fatty acid composition. Phospholipid EPA and DHA increased markedly, reaching 10.0% and 5.9 mol%, respectively, by 18 mo (cf. 相似文献   

Lipid and fatty acid composition of muscle and liver from wild and captive mature female broodstocks of white seabream, Diplodus sargus

Total lipids (TL), lipid classes, and their associated fatty acids from muscle and liver of captive and wild mature female broodstocks were investigated in order to estimate the fatty acid requirements of white seabream (Diplodus sargus). The results showed that the percentage of triacylglycerol was higher in liver and muscle of captive fish than in wild fish. The distribution of phospholipid classes in liver and muscle of both fish groups was similar, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol being the predominant lipid classes. The general pattern of fatty acid distribution in total lipid of liver and muscle from captive and wild fish was similar. However, the relative percentage of specific fatty acids differed in captive and wild fish. The most noteworthy difference was the lower proportion of arachidonic acid (20:4n-6, AA) and the higher proportion of eicosapentaenoic acid (20:5n-3, EPA) in liver and muscle of captive fish with respect to those of wild fish. The proportion of docosahexaenoic acid (22:6n-3, DHA) did not differ between the two fish groups. The differences in EPA and AA proportions between captive and wild fish implied that captive fish presented a higher EPA/AA ratio and a lower DHA/EPA ratio than wild fish. In general terms, in both liver and muscle, the differences in fatty acid composition observed for TL were extended to all lipid classes. The results suggest that the different AA, EPA and DHA proportions in liver and muscle between captive and wild broodstocks are attributed to different levels of these fatty acids in broodstock diets.     

Utilisation of fish oil in ruminants: II. Transfer of fish oil fatty acids into goats’ milk

A study was conducted to determine the transfer of eicosapentaenoic acid (EPA, 20:5) and docosahexaenoic acid (DHA, 22:6) from fish oil into goats’ milk. Goats were sequentially offered three diets: control (C) pellets (lucerne hay-oat grain: 60/40 w/w), C plus tuna oil protected against ruminal biohydrogenation (PTO pellets), and C plus unprotected tuna oil (UTO pellets). In supplemented diets, tuna oil constituted 3% of total dry matter (DM), and each supplement was fed for 7 days, with 12 days allowed between the two fish oil feeding periods to minimise carry-over effects. Dry matter intake, milk yield, protein and fat yield were reduced by feeding UTO, but not PTO, pellets. Goats produced ω-3 enriched milk (0.3–0.5% EPA and 1.01–1.12% DHA) when fed either supplement. The rate of transfer of dietary EPA and DHA to milk ranged from 3.5 to 7.6%. Significant transfer of EPA and DHA from tuna oil into goat milk, without deleterious effects on intake or milk yield is possible, provided that the oil supplement is substantially protected against ruminal biohydrogenation.     

Dietary and seasonal effects on the dorsal meat lipid composition of Japanese (Silurus asotus) and Thai catfish (Clarias macrocephalus and hybrid Clarias macrocephalus and Clarias galipinus)

The effects of dietary lipids and seasonal variation on the lipids of wild and cultured catfish (Japanese catfish, Silurus asotus; Thai catfish, Clarias macrocephalus and hybrid Clarias macrocephalus x Clarias galipinus) were determined by analysis of the lipid content and fatty acid composition of their dorsal meat. The predominant fatty acids of dorsal meat were 16:0, 18:1n-9, 18:2n-6, 20:4n-6 (arachidonic acid, AA), and 22:6n-3 (docosahexaenoic acid, DHA). The DHA content in the diet of Japanese catfish was higher than that in the diet of Thai catfish, and this was reflected in the dorsal meat of the Japanese catfish, which had a remarkably high percentage of DHA compared with the meat of the Thai catfish. Cultured Japanese catfish had a higher percentage of 18:2n-6 than Thai fish and a lower percentage of AA in winter than in summer season. There were also seasonal variations in the percentage of n-6 fatty acids in Japanese catfish. In summer, the fatty acid composition of the cultured Japanese catfish was similar to that of the wild catfish. These fatty acid changes in the lipid classes, triacylglycerol, phosphatidylcholine and phosphatidylethanolamine were similar to those observed for total lipids. These results indicate that the percentage of DHA in the dorsal meat of catfish is influenced by dietary fatty acid, and it may be that it can be increased in cultivated fish by administering a diet containing a large amount of DHA.     

Partial replacement of dietary fish oil with blends of vegetable oils (rapeseed, linseed and palm oils) in diets for European sea bass (Dicentrarchus labrax L.) over a long term growth study: effects on muscle and liver fatty acid composition and effectiveness of a fish oil finishing diet

Triplicate groups of European sea bass (Dicentrarchus labrax L.), of initial mass 5 g, were fed one of three practical type diets for 64 weeks. The three diets differed only in the added oil and were 100% fish oil (FO; diet A), 40% FO/60% vegetable oil blend (VO; diet B) where the VO blend was rapeseed oil, linseed oil and palm oil in the ratio 10/35/15 by weight and 40% FO/60% VO blend (diet C) where the ratio was 24/24/12 by weight. After final sample collection the remaining fish were switched to a 100% FO finishing diet for a further 20 weeks. After 64 weeks fish fed 60% VO diet B had significantly lower live mass and liver mass than fish fed diets A and C although SGR, FCR and length were not different between groups. There were no differences in any of the above parameters after either 14 or 20 weeks on the FO finishing diet. Fatty acid compositions of flesh were correlated to dietary fatty acids although there was selective retention of docosahexaenoic acid (22:6n-3; DHA) regardless of dietary input. Inclusion of dietary VO resulted in significantly reduced flesh levels of DHA and eicosapentaenoic acid (20:5n-3; EPA) while 18:1n-9, 18:2n-6 and 18:3n-3 were all significantly increased in fish fed the 60% VO diets. Fatty acid compositions of liver showed broadly similar changes, as a result of dietary fatty acid composition, as was seen in flesh. However, the response of flesh and liver to feeding a FO finishing diet was different. In flesh, DHA and EPA values were not restored after 14 or 20 weeks of feeding a FO finishing diet with the values in fish fed the two 60% VO diets being around 70% of the values seen in fish fed FO throughout. Conversely, and despite liver DHA and EPA levels being reduced to only 40% of the value seen in fish fed 100% FO after 64 weeks, the levels of liver DHA and EPA were not significantly different between treatments after feeding the FO finishing diet for 14 weeks. However, a 200 g portion of sea bass flesh, after feeding the experimental diets for 64 weeks followed by a FO diet for 14 weeks, contained 1.22 and 0.95 g of EPA + DHA for fish fed FO or 60% VO, respectively. Therefore, sea bass grown for most of the production cycle using diets containing 60% VO can still contribute a significant quantity of healthy n-3 HUFA to the human consumer.     

Replacement of dietary fish oil for Atlantic salmon parr (Salmo salar L.) with a stearidonic acid containing oil has no effect on omega-3 long-chain polyunsaturated fatty acid concentrations

The worldwide increase in aquaculture production and the concurrent decrease of wild fish stocks has made the replacement of fish oil in aquafeeds an industry priority. Oil from a plant source Echium plantagineum L., Boraginaceae, has high levels of stearidonic acid (SDA, 18:4omega3, 14%) a biosynthetic precursor of omega-3 long-chain (> or =C(20)) polyunsaturated fatty acids (omega3 LC-PUFA). Atlantic salmon (Salmo salar L.) parr were fed a control fish oil diet (FO) or one of 3 experimental diets with 100% canola oil (CO) 100% SDA oil (SO), and a 1:1 mix of CO and SDA oil (MX) for 42 days. There were no differences in the growth or feed efficiency between the four diets. However, there were significant differences in the fatty acid (FA) profiles of the red and white muscle tissues. Significantly higher amounts of SDA, eicosapentaenoic acid (20:5omega3, EPA), docosahexaenoic acid (22:6omega3, DHA) and total omega3 FA occurred in both red and white muscle tissues of fish fed SO and FO compared with those fed CO. Feeding SO diet resulted in omega3 LC-PUFA amounts in the white and red muscle being comparable to the FO diet. This study shows that absolute concentration (mug/g) of EPA, DHA and total omega3 have been maintained over 6 weeks for Atlantic salmon fed 14% SDA oil. The balance between increased biosynthesis and retention of omega3 LC-PUFA to maintain the concentrations observed in the SO fed fish remains to be conclusively determined, and further studies are needed to ascertain this.     

The Fat-1 Mouse has Brain Docosahexaenoic Acid Levels Achievable Through Fish Oil Feeding

Fat-1 transgenic mice endogenously convert n-6 to n-3 polyunsaturated fatty acids (PUFA). The aims of this study were to test whether a) fish oil feeding can attain similar brain n-3 PUFA levels as the fat-1 mouse, and b) fat-1 mouse brain docosahexaenoic acid (22:6n-3; DHA) levels can be potentiated by fish oil feeding. Fat-1 mice and their wildtype littermates consumed either a 10% safflower oil (SO) or a 2% fish oil and 8% safflower oil chow (FO). Brain total lipid and phospholipid fraction fatty acids were analyzed using GC-FID. Wildtype mice fed FO chow had similar brain levels of DHA as fat-1 mice fed SO chow. Fat-1 mice fed FO chow had similar brain n-3 PUFA levels as fat-1 mice fed SO chow. In conclusion, brain levels of DHA in the fat-1 mouse can be obtained by and were not further augmented with fish oil feeding.     

Dietary polyunsaturated fatty acids (C18:2 omega6 and C18:3 omega3) do not suppress hepatic lipogenesis

Omega 3 polyunsaturated fatty acids are promoted as beneficial in the prevention of metabolic and cardiovascular diseases. In general, dietary omega 3 fatty acids are derived from plant sources as linolenic acid (LNA, C18:3 omega3) the precursor to eicosapentaenoic acid (EPA, C20:5 omega3) and docosahexaenoic acid (DHA, C22:6 omega3). However, it remains unclear if the polyunsaturated fatty acid (PUFA) LNA can provide the same health benefits as the very long chain highly unsaturated fatty acids (HUFA) EPA and DHA generally derived from oily fish. In this study, mice were fed synthetic diets containing lard (low in PUFA and HUFA), canola oil (to supply PUFA), or a mixture of menhaden and arasco (fish and fungal) oils (to supply HUFA) for 8 weeks. The diets were neither high in calories nor fat, which was supplied at 6%. The lard and canola oil diets resulted in high levels of hepatic triglycerides and cholesterol and elevation of lipogenic gene expression. By comparison livers from mice fed the fish/fungal oil diet had low levels of lipid accumulation and more closely resembled livers from mice fed standard laboratory chow. SREBP1c and PPARgamma gene and protein expression were high in livers of animals fed diets containing lard or canola oil compared with fish/fungal oil. Hepatic fatty acid analyses indicated that dietary PUFA were efficiently converted to HUFA regardless of source. Therefore, differences in hepatic lipid levels and gene expression between dietary groups were due to exogenous fatty acid supplied rather than endogenous pools. These results have important implications for understanding the regulation of hepatic lipogenesis by dietary fatty acids.     

Ingestion rates and dietary lipids affect growth and fatty acid composition of Dendraster excentricus larvae

This study investigated the effect of single and mixed algal diets on growth, fatty acid composition and ingestion rates for Dendraster excentricus larvae. Larvae were assigned to three single algal diet treatments Isochrysis galbana, Dunaliella tertiolecta or Rhodomonas sp. and four mixed algal diet treatments D. tertiolecta and Rhodomonas, I. galbana and D. tertiolecta, I. galbana and Rhodomonas, D. tertiolecta, Isochrysis galbana and Rhodomonas sp. Small amounts (0.36-0.6%) of stearic acid (18:0) were seen in the three algae used but a relatively large percentage (7-25%) of this SAFA was found in Dendraster larvae. The alga D. tertiolecta had the highest percentage (51.7%) of the short chain polyunsaturated fatty acid (PUFA) linolenic acid 18:3(n-3) and trace amounts (0.02-0.14%) of the long chain PUFAs eicosapentanoic (EPA, 20:5(n-3) and docosahexanoic acids (DHA, 22:6(n-3)). However, sand dollar larvae demonstrated the ability to elongate and desaturate shorter chain (18 carbon) polyunsaturated fatty acids (PUFA) to longer chain (20 carbon) n-3 PUFA. Thus high levels of 18:3(n-3) in D. tertiolecta led to high levels of EPA and low levels of 18:3(n-3) in Dendraster larvae fed this diet. Rhodomonas sp. had the highest percentage of stearidonic acid (18:4(n-3), 38.14%) and EPA (10.6%). Despite high levels of 18:4(n-3) in Rhodomonas sp. this acid was absent or found at very low levels in larvae fed this alga, or any combination of this alga. I. galbana had the highest percentage of DHA(14.3%) but was almost devoid of EPA (0.43%). Although Rhodomonas sp. and I. galbana had high levels of EPA and DHA sand dollar larvae did not incorporate higher levels of these long chain PUFAs into their lipids compared to those fed the alga D. tertiolecta. Dendraster larvae synthesized a number of 20 and 22 carbon non-methylene interrupted dienes (NMID), with levels increasing with larval stage. Higher ingestion rates were observed for Dendraster larvae fed single algal diets (Rhodomonas sp. or D. tertiolecta) and lower ingestion rates for those fed mixed algal diets. The highest ingestion rates were for 8-arm Dendraster larvae fed the large alga Rhodomonas sp. presented as a single algal diet. When fed a combination of three algae, selection of particles varied slightly depending on stage with 8-arm larvae ingesting slightly more of the larger algal cell in the mixture than 6-arm larvae. The present study suggests that regardless of the ratios given larvae might have an optimum ratio of different sized particles at which they can feed. The mixed algal diet of I. galbana and D. tertiolecta was the best algal diet leading to significantly larger larvae with high survival and development to metamorphosis. The single algal diets of Rhodomonas sp. or Dunaliella tertiolecta were the second and third best algal diets based on growth and survival to metamorphosis.     

Effect of frozen storage on fatty acid composition and changes in lipid content of Scomberomorus commersoni and Carcharhinus dussumieri

Investigated were the changes in fatty acid composition, oxidation and enzymatic deterioration of lipids in frozen (−30°C) fish fillets from the Persian Gulf. The narrow barred Spanish mackerel ( Scomberomorus commersoni ) and white cheek shark ( Carcharhinus dussumieri ) were tested with storage times of 0, 1, 2, 3, 4, 5 and 6 months at −18°C. Statistical results showed that the major fatty acids among the saturated and monounsaturated fatty acids of each fish species were palmitic (C16:0) and oleic (C18:1n-9) acids, respectively. Both linoleic acid (C18:2n-6) and arachidonic acid (AA) (C20:4n-6) were predominant in total n-6 polyunsaturated fatty acids in both mackerel and shark. The EPA (eicosapentaenoic acid; C20:5 n-3) and DHA (docosahexaenoic acid; C22:6 n-3) acids were the major fatty acids among total n-3 acids in both fishes. During frozen storage, the PUFA (40.1 and 23.94%), n-3 (48 and 42.83%), ω 3/ ω 6 (41.36 and 50%), PUFA/SFA (56 and 42.23%) and EPA + DHA/C16 (55.55 and 46.66%) contents decreased in S. commersoni and C. dussumieri , respectively. Also peroxide, thiobarbituric acid (TBA) and free fatty acid (FFA) values significantly increased (P < 0.01) with the time of storage.     

Effect of randomized supplementation with high dose olive, flax or fish oil on serum phospholipid fatty acid levels in adults with attention deficit hyperactivity disorder

Dietary intake of omega-3 fatty acids has been positively correlated with cardiovascular and neuropsychiatric health in several studies. The high seafood intake by the Japanese and Greenland Inuit has resulted in low ratios of the omega-6 fatty acid arachidonic acid (AA, 20:4n-6) to eicosapentaenoic acid (EPA, 20:5n-3), with the Japanese showing AA:EPA ratios of approximately 1.7 and the Greenland Eskimos showing ratios of approximately 0.14. It was the objective of this study to determine the effect of supplementation with high doses (60 g) of flax and fish oils on the blood phospholipid (PL) fatty acid status, and AA/EPA ratio of individuals with Attention Deficit Hyperactivity Disorder (ADHD), commonly associated with decreased blood omega-3 fatty acid levels. Thirty adults with ADHD were randomized to 12 weeks of supplementation with olive oil (< 1% omega-3 fatty acids), flax oil (source of alpha-linolenic acid; 18:3n-3; alpha-LNA) or fish oil (source of EPA and docosahexaenoic acid; 22:6n-3; DHA). Serum PL fatty acid levels were determined at baseline and at 12 weeks. Flax oil supplementation resulted in an increase in alpha-LNA and a slight decrease in the ratio of AA/EPA, while fish oil supplementation resulted in increases in EPA, DHA and total omega-3 fatty acids and a decrease in the AA/EPA ratio to values seen in the Japanese population. These data suggest that in order to increase levels of EPA and DHA in adults with ADHD, and decrease the AA/EPA ratio to levels seen in high fish consuming populations, high dose fish oil may be preferable to high dose flax oil. Future study is warranted to determine whether correction of low levels of long-chain omega-3 fatty acids is of therapeutic benefit in this population.