Retention Of Fatty Acids Research Articles

Easy Method for Removal of Cyanogens from Cassava Leaves with Retention of Vitamins and Omega-3 Fatty Acids

Currently there is a crescent interest regarding the use of vegetable by-products for food fortification, in order to improve its nutritional quality. Cassava leaves are suitable as nutritional additives, however their cyanide content must be reduced to below 10 mg kg-1 of dry product. Thus, it was developed a method in drying laboratory oven which is able to reduce 99.85% of cyanide present in manioc leaves (from 35 mg kg-1 to 0.05 mg kg-1) while being 509% faster than the traditional method, and without substantial loss of omega-3 fatty acids and β-carotene.

Atlantic salmon require long-chain n-3 fatty acids for optimal growth throughout the seawater period.

The nutritional requirement for n-3 long-chain PUFA in fast-growing Atlantic salmon (Salmo salar) during grow out in the sea is not well documented. Diets were formulated with levels of EPA (20 : 5n-3) and DHA (22 : 6n-3) ranging from 1·3 to 7·4 % of fatty acids (4-24 g/kg feed). Two long-term trials were conducted through the seawater phase, the first at 6 and 12°C, and the second at 12°C. In the first trial, growth at both temperatures was significantly lower in fish fed 1·4 % EPA+DHA of total fatty acids compared with the 5·2 % EPA+DHA group. In the second trial, growth was significantly lower in fish fed 1·3 and 2·7 % compared with 4·4 and 7·4 % EPA + DHA. Fatty acid composition in the fish reflected diet composition, but only after a 7-fold increase in body weight did the fatty acid profile of the fish stabilise according to dietary fatty acids (shown for EPA and DHA). The retention efficiency of DHA increased with decreasing dietary levels, and was 120-190 and 120-200 % in trials 1 and 2, respectively. The retention efficiency of EPA was lower (60-200 %), and values >100 % were only achieved at the lowest dietary levels in both trials. Temperature did not affect fatty acid retention efficiency. These results suggest that Atlantic salmon have a specific requirement for EPA + DHA >2·7 % of fatty acids for optimal long-term growth in seawater, and that short-term growth trials with less weight increase would not show these effects.

Сопоставление эффективности методов ГЖХ и ВЭЖХ при дифференциации растительных масел, содержащих изомеры октадекатриеновых кислот

The comparison of the effectiveness of the methods of gas chromatographic (GC) analysis of methyl esters derived from seed oils ( I ) and reversed-phase high-performance liquid chromatography of native triacylglycerols (TAG) ( II ) for the differentiation of four oils, which include moieties of four isomeric octadecatrienoic not-conjugated fatty acids, was investigated. It was shown that in method I the retention of methyl esters of isomeric C18:3 acids increases in the following order: γ-linolenic (C18:3 6Z9Z12Z ) ‒ pinolenic (C18:3 5Z9Z12Z ) ‒ columbinic (C18:3 5E9Z12Z ) ‒ α-linolenic (C18:3 9Z12Z15Z ). For the esters the equivalent carbon numbers ( ECN ) were calculated on a scale of the saturated fatty acids retention. It was shown that the method I can reliably differentiate oils with α-linolenic, γ-linolenic and pinolenic (or columbinic) acids, whereas the differentiation of oils containing pinolenic and columbinic acid moieties requires careful control of the retention times. Method II allowed differentiating oils of all four isomeric C18:3 acids because the increment for the replacement of linoleic acid by these octadecatrienoic acids sequentially varies by the magnitude allowing for the reliable differentiation. The order of retention of the same types of TAG in method II differs from the order of elution of methyl esters in method I . TAGs retention increased in the following order: α-linolenic - γ-linolenic – pinolenic – columbinic acids. Keywords : GLC, reverse phase HPLC, fatty acids methyl esters, triacylglycerols, retention parameters, isomeric octadecatrienoic acids DOI: http://dx.doi.org/10.15826/analitika.2016.20.4.002 Victor I. Deineka 1* , Alexander V. Turtygin 2 , Liudmila A. Deineka 1 1 Belgorod National Research University, Institute of Engineering Technology and Natural Science, Pobeda ul. 85, Belgorod, 308015, Russian Federation 2 Laboratory quality of LLC "City supermarket", 121170, Moscow, Kutuzovsky prosp., 36, build. 6.

A new F-18 labeled PET tracer for fatty acid imaging

In the presence of acute or chronic myocardial ischemia, myocardial energy metabolism is shifted from the use of aerobic fatty acids (FA) substrate to anaerobic glucose utilization resulting in decreased FA uptake in ischemic regions. This phenomenon may persist as long as 24-30 hours following an acute ischemic event, despite restoration of blood flow and resolution of symptoms and is referred as “ischemic memory”.1 Ischemic memory imaging can be particularly useful in various clinical settings2 as in the case of patients presenting to the emergency department with acute chest pain syndrome.3 We present the first human images of CardioPET (trans-9-F-18-fluoro-3,4-methyleneheptadecanoic acid, FCPHA)4 a F-18 labeled modified FA currently being evaluated in a phase II multicentre clinical trial in patients with a positive SPECT stress test for ischemia. A 69-year-old man with typical angina was evaluated using bicycle exercise stress-rest Tc-99m-Sestamibi SPECT (Figure 1). As part of a research protocol, prior to coronary angiography, the patient underwent repeat bicycle stress CardioPET imaging at a similar heart rate. CardioPET was injected 8 minutes after peak exercise stress test. CardioPET images (Figure 2) revealed alterations of fatty acid uptake in regions without abnormalities on Tc-99m-Sestamibi-SPECT (Figure 3). It better identified the extent of significant coronary stenosis than did Tc-99m-Sestamibi SPECT as demonstrated by coronary angiography (Figure 4). In addition, regional time-activity curves obtained from the CardioPET data suggested dynamic time-dependent changes in fatty acid retention in ischemic regions different from the non-ischemic regions that need to be further investigated (Figure 5). These preliminary findings suggest a promising role of this new F-18 labeled tracer of FA uptake for the identification of functionally significant coronary artery disease. FA uptake and retention in various pathophysiological conditions may be better understood using the quantitative capabilities of PET technology. Figure 1 Attenuation corrected stress-rest Tc-99m-Sestamibi perfusion SPECT images. Sestamibi was injected at the peak of the stress test (160 watts, 131 bpm, 86% of maximal predicted heart rate and blood pressure of 210/100 mm Hg). ... Figure 2 CardioPET images. CardioPET enters the myocardium by the same mechanism as naturally occurring free FAs and then undergoes partial metabolism before being trapped in the myocytes. The tracer (262 MBq) was injected 8 minutes after peak ... Figure 3 Slice by slice comparison of the stress perfusion SPECT, CardioPET, and rest perfusion SPECT images allowing to appreciate the more extensive defects on the cardioPET scan in relation to the Tc-99m-Sestamibi stress perfusion SPECT scan Figure 4 Coronary angiography. Coronary angiography revealed multi-vessel disease with a severe (76%-95%) ostial lesion of the circumflex artery (yellow arrow), 2 successive severe (76%-95%) medial lesions of the left anterior descending artery, a severe (76%-95%) ... Figure 5 CardioPET time-activities curves. The graph shows the evolution of the activity in the different regions of the left ventricle (lateral, posterior, inferior, septal, anteroseptal, and anterior) as a function of the time after tracer injection. Counts ...

The Effects of Diets Containing Standard Soybean Oil, Soybean Oil Enhanced with Conjugated Linoleic Acids, Menhaden Fish Oil, or an Algal Docosahexaenoic Acid Supplement on Juvenile Channel Catfish Performance, Hematology, Body Composition, and Nonspecific Immune Response

AbstractTo reduce diet cost and address environmental concerns, current commercial diets for Channel Catfish Ictalurus punctatus contain little or no marine fish oil. However, there are conflicting data on the effects of fish oil and other lipid sources for juvenile Channel Catfish, and some novel lipids have not been tested against traditional ones. In this study, the effects of four different lipid sources for potential use in juvenile Channel Catfish diets were investigated by measuring fish growth performance, proximate and fatty acid composition of muscle, nonspecific immune response, and hematological parameters. In a 63‐d feeding trial, juveniles (mean weight ± SE = 11.2 ± 0.0 g) were fed a commercial 32% protein diet supplemented with 2% lipid from standard soybean oil (SBO; control diet), SBO enriched with conjugated linoleic acids (CLAs; CLA diet), algal (Schizochytrium sp.) docosahexaenoic acid (DHA) extract (DHA diet), or menhaden fish oil (MFO diet). Fish that were fed the MFO diet had improved feed conversion compared with fish that were fed the SBO, CLA, or DHA diet. There were no other differences in fish growth performance or proximate composition and no differences among treatments in nonspecific immune responses or hematological parameters. As expected, fatty acid composition of fish muscle reflected that of the diets: fish that received the MFO, DHA, or CLA diet contained higher levels of healthful fatty acids (DHA or CLAs) than fish that were given the SBO control diet. Future trials will address methods for (1) increasing target levels of these fatty acids by using diets with little or no fish oil and (2) optimizing retention of desirable fatty acids to facilitate the production of Channel Catfish as a high‐value functional food.

Marginal efficiencies of long chain-polyunsaturated fatty acid use by barramundi (Lates calcarifer) when fed diets with varying blends of fish oil and poultry fat

An experiment was conducted with barramundi (Lates calcarifer) juveniles to examine the marginal efficiency of utilisation of long chain-polyunsaturated fatty acids (LC-PUFA). A series of five diets with blends of fish (anchovy) oil and poultry fat (F100:P0, F60:P40, F30:P70, F15:P85, F0:P100) were fed to 208±4.1g fish over a 12-week period. The replacement of fish oil with poultry fat had no impact on growth performance (average final weight of 548.3±10.2g) or feed conversion (mean=1.14±0.02). Analysis of the whole body composition showed that the fatty acid profile reflected that of the fed diet. However it was also shown that there was a disproportional retention of some fatty acids relative to others (notably LOA, 18:2n-6 and LNA, 18:3n-3). By examining the body mass independent retention of different fatty acids with differential levels of intake of each, the marginal efficiencies of the use of these nutrients by this species were able to be determined. The differential retention of fatty acids in the meat was also examined allowing the determination of oil blending strategies to optimise meat n-3 LC-PUFA levels.

Trans fatty acid retention and conversion rates of fatty acids in tissues depend on dietary fat in mice

Given that the effects of trans fatty acids (TFA) may be associated with the type of TFA isomer and the proportion of n‐3/n‐6/n‐9 fatty acids (FA), this work aimed to investigate the influence of different oils on the following parameters: content, incorporation, and retention of TFA; conversion of vaccenic acid (VA) to rumenic acid (RA) in different tissues; and hepatic output of TFA by VLDL. Another objective was to assess relative conversion rates of key FA and the potential alteration of FA composition induced by TFA in tissues. Male CF1 mice were fed (30‐days) diets containing 7% olive, corn or rapeseed oils either supplemented with 0.75% of TFA or without added TFA. FA composition of liver, epididymal adipose tissue, gastrocnemius muscle, brain, and serum was assessed. With the exception of the brain, TFAs were incorporated into the analyzed tissues and serum. TFA retention and RA bioconversion from VA depended on the dietary unsaturated FA proportions. The higher levels of hepatic RA in the liver of mice fed an olive oil+TFA diet could be associated with a raised Δ9‐desaturase index. The FA composition of tissues was scarcely modified by the consumption of partially hydrogenated vegetable oils containing similar proportions of t9‐, t10‐, and t11‐18:1.Practical applications: The present study evaluates the interaction of hydrogenated vegetable oils with different edible oils and the impact on the FA profile and, specifically, TFA incorporation and retention in the tissues. Since the characterization of FA present in tissues might be determining the biological effects of edible fats, this study is relevant for elucidation of existing controversial findings associated with the intake of TFA and its effects on human metabolic alterations.The levels of trans fatty acids (TFA) in a particular tissue might be related to different variables including: type and level of the dietary TFA isomer; uptake, metabolization and release from the tissue, and interference with different dietary fatty acids.

Effects of dietary concentrated mannan oligosaccharides supplementation on growth, gut mucosal immune system and liver lipid metabolism of European sea bass (Dicentrarchus labrax) juveniles

The study assesses the effects of dietary concentrated mannan oligosaccharides (cMOS) on fish performance, biochemical composition, tissue fatty acid profiles, liver and posterior gut morphology and gen expression of selected parameters involved on the intestinal immune response and liver lipid metabolism of European sea bass (Dicentrarchus labrax).For that purpose, specimens of 20 g were fed during 8 weeks at 0 and 1.6 g kg−1 dietary cMOS of inclusion in a commercial sea bass diet. Dietary cMOS enhanced fish length, specific and relative growth without affecting tissue proximate composition. However, cMOS supplementation altered especially liver and muscle fatty acid profiles by reducing levels of those fatty acids that are preferential substrates for β-oxidation in spite of a preferential retention of long chain polyunsaturated fatty acids (LC-PUFA), such as 20:4n-6 or 22:5n-6, in relation to the down-regulation of delta 6/5 desaturase gene expression found in liver. Besides, dietary cMOS supplementation reduced posterior gut intestinal folds width and induced changes on the gene expression level of certain immune-related genes mainly by down regulating transforming growth factor β (TGFβ) and up-regulating immunoglobulin (Ig), major histocompatibility complex class II (MHCII), T cell receptor β (TCRβ) and Caspase 3 (Casp-3).Thus, dietary cMOS inclusion at 0.16% promoted European sea bass specific growth rate and length, stimulated selected cellular GALT-associated parameters and affected lipid metabolism in muscle and liver pointing to a higher LC-PUFA accumulation and promoted β-oxidation.

Quality enhancement of the abundant under‐valued crustacean, lobster krill (Munida spp.), during its chilled storage

SummaryLobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product.

Near-real-time analysis of the phenotypic responses of Escherichia coli to 1-butanol exposure using Raman Spectroscopy.

Raman spectroscopy was used to study the time course of phenotypic responses of Escherichia coli (DH5α) to 1-butanol exposure (1.2% [vol/vol]). Raman spectroscopy is of interest for bacterial phenotyping because it can be performed (i) in near real time, (ii) with minimal sample preparation (label-free), and (iii) with minimal spectral interference from water. Traditional off-line analytical methodologies were applied to both 1-butanol-treated and control cells to draw correlations with Raman data. Here, distinct sets of Raman bands are presented that characterize phenotypic traits of E. coli with maximized correlation to off-line measurements. In addition, the observed time course phenotypic responses of E. coli to 1.2% (vol/vol) 1-butanol exposure included the following: (i) decreased saturated fatty acids levels, (ii) retention of unsaturated fatty acids and low levels of cyclopropane fatty acids, (iii) increased membrane fluidity following the initial response of increased rigidity, and (iv) no changes in total protein content or protein-derived amino acid composition. For most phenotypic traits, correlation coefficients between Raman spectroscopy and traditional off-line analytical approaches exceeded 0.75, and major trends were captured. The results suggest that near-real-time Raman spectroscopy is suitable for approximating metabolic and physiological phenotyping of bacterial cells subjected to toxic environmental conditions.

Effect of cooking method on the fatty acid content of reduced-fat and PUFA-enriched pork patties formulated with a konjac-based oil bulking system

The effect of cooking methods (electric grilling and pan-frying in olive oil) on the composition of reduced-fat and reduced-fat/PUFA enriched pork patties was studied. Fat reduction was performed by replacing pork backfat (38% and 100%) with konjac gel and PUFA-enrichment by replacing pork backfat (49%) with a konjac-based oil bulking system stabilizing a healthier oil combination (olive, linseed and fish oils). Cooking losses (13%–27%) were affected (p<0.05) by formulation and cooking procedure. Compared with raw products, cooked samples had higher (p<0.05) concentrations of MUFAs and PUFAs (both n-3 and n-6); the difference was greater (p<0.05) in the pan-fried patties. Fatty acid retention was generally better in pan-fried than in grilled samples. When cooked, the PUFA levels in the medium-fat/improved sample containing the oil bulking system ranged between 1.4 and 1.6g/100g (0.47–0.51 from n-3 PUFAs), with EPA+DHA concentrations of around 75mg/100g. Konjac materials were successfully used to produce pork patties with a better lipid composition.

Biochemical egg quality in a captive walleye (Sander vitreus) broodstock population relative to ovulation timing following hormonal treatment

The aim of this study was to evaluate how variations in total lipids, fatty acids, and total and free amino acids in eggs affect embryonic development throughout the spawning season in cultured walleye (Sander vitreus). Eggs were obtained from 4-year-old females and pooled based on spawning time: they were assigned to four consecutive periods during a one-month spawning season according to the first spawning occurrence in the female broodstock. Hatching success was significantly higher at the intermediate spawning period (87.3 ± 2.4%), and no eggs hatched in the late spawning group (p < 0.05). Egg diameter was significantly larger for the two intermediate spawning periods, which is related to the greater larval length at hatch during these two periods. Successful development was associated with the quality of lipid reserves throughout ontogeny. For polar fatty acids, there was a specific retention of essential fatty acids (EFA), particularly of the most abundant, i.e., docosahexaenoic acid (DHA), which made up more than 40% of the polar fatty acid fraction. For total amino acids, lysine (LYS) and serine (SER) levels were significantly higher in eggs from the intermediate spawning periods and were preferentially depleted during embryogenesis. During embryogenesis, energy was derived primarily from triacylglycerols (TAG), proteins, and non-essential free amino acids. Our results suggest that the content of EFA and amino acids in eggs may explain differences in egg quality and success of larval development within a broodstock population. Our results clearly show that the timing of ovulation during the spawning period affects the success of walleye aquaculture production.

Interactions between dietary docosahexaenoic acid and other long-chain polyunsaturated fatty acids on performance and fatty acid retention in post-smolt Atlantic salmon (Salmo salar)

A study with varying dietary inclusion levels (1, 5, 10, 15 and 20 g kg(-1)) of docosahexaenoic acid (DHA; 22:6n-3) was conducted with post-smolt (111 ± 2.6 g; mean ± S.) Atlantic salmon (Salmo salar) over a 9-week period. In addition to the series of DHA inclusion levels, the study included further diets that had DHA at 10 g kg(-1) in combination with either eicosapentaenoic acid (EPA; 20:5n-3) or arachidonic acid (ARA; 20:4n-6), both also included at 10 g kg(-1). An additional treatment with both EPA and DHA included at 5 g kg(-1) (total of 10 g kg(-1) long-chain polyunsaturated fatty acids, LC-PUFA) was also included. After a 9-week feeding period, fish were weighed, and carcass, blood and tissue samples collected. A minor improvement in growth was seen with increasing inclusion of DHA. However, the addition of EPA further improved growth response while addition of ARA had no effect on growth. As with most lipid studies, the fatty acid composition of the whole body lipids generally reflected that of the diets. However, there were notable exceptions to this, and these implicate some interactions among the different LC-PUFA in terms of the fatty acid biochemistry in this species. At very low inclusion levels, DHA retention was substantially higher (~250%) than that at all other inclusion levels (31-58%). The inclusion of EPA in the diet also had a positive effect on the retention efficiency of DHA. However, EPA retention was highly variable and at low DHA inclusion levels there was a net loss of EPA as this fatty acid was most likely elongated to produce DHA, consistent with increased DHA retention with additional EPA in the diet. Retention of DPA (22:5n-3) was high at low levels of DHA, but diminished with increasing DHA inclusion, similar to that seen with DHA retention. The addition of EPA to the diet resulted in a substantial increase in the efficiency of DPA retention; the inclusion of ARA had the opposite effect. Retention of ARA was unaffected by DHA inclusion, but the addition of either EPA or ARA to the diet resulted in a substantial reduction in the efficiency of ARA retention. No effects of dietary treatment were noted on the retention of either linolenic (18:3n-3) or linoleic (18:2n-6) acids. When the total n-3 LC-PUFA content of the diet was the same but consisted of either DHA alone or as a combination of EPA plus DHA, the performance effects were similar.

Revealing organic carbon sources fueling a coral reef food web in the Gulf of Mexico using stable isotopes and fatty acids

Carbon and nitrogen stable isotopes and fatty acids (FAs) revealed primary producer organic carbon sources that fuel a coral reef food web with river influence. A stable isotope mixing model was used to assess the relative contribution of six different primary producers to nine of the most ubiquitous invertebrate and fish consumer's bulk carbon. Mangrove and phytoplankton were difficult to differentiate in some consumers; likely solutions involved one or the other but not both at the same time. FA concentration in upper trophic levels was corrected for the primary producer's relative contribution according to the mixing model, and FA retention was evaluated using a calculated trophic retention factor (TRF). The C18 FAs, 18:2ω6 and 18:3ω3, were plentiful in mangrove, sea grass, and green algae, but decreased across trophic levels with a TRF ≤ 1, probably due to decomposition of drifting leaves and then consumer metabolism. In contrast, macroalgae and phytoplankton FAs, 24:1ω9, and highly unsaturated fatty acids (HUFAs), arachidonic acid (ARA) 20:4ω6, docosapentanoic acid (DPA) 22:5ω3, and docosahexanoic acid (DHA) 22:6ω3, showed trophic accumulation (TRF &gt; 1), while eicosapentanoic acid (EPA) 20:5ω3 had similar concentrations across trophic levels (TRF = 1), suggesting the following degrees of HUFA retention: DHA &gt; ARA &gt; EPA. This study indicates that phytoplankton are the major source of essential dietary nutrients for all fish, and that dietary energy from mangroves is transferred to juvenile fish Caranx hippos, while sea grass nonessential FAs are transferred to the entire food web. Moreover, among the species studied, the sea urchin Echinometra lucunter is the major consumer of brown and green algae, while red algae were also consumed by the surgeon fish Acanthurus chirurgus.

Influence of Extrusion Processing on Fatty acids Retention in Full-fat Flaxseed (Linum usitatissimum L.) Meal

Background: Flaxseed (Linum usitatissimum L.) provides multiple nutritional benefits including high quality protein, dietary fiber and is the most abundant source of α-linolenic acid (C 18:3). This study focuses on the effect of extrusion processing on fatty acids retention in full-fat flaxseed meal. The ranges of processing variables selected using central composite design were: barrel exit temperature (BET) of 76.3-143.6°C; screw speed (SS) of 59.6-160.5 rpm and feed rate (FR) of 26.4-93.6 kg/h. Results: The extrusion processing at different barrel temperatures, screw speed and feed rate did not showed gradual decrease or increase in palmitic, stearic, oleic and linoleic acid contents. The amount of α-linolenic acid retention in extruded samples ranged from 92% to 99.2%. Optimal operating conditions were established; BET (138.4-138.8°C), SS (160-160.5 rpm) and FR (26.4-34.1 kg/h) for maximum (98.3-98.8%) retention of α-linolenic acid. This effect was mainly dependent on BET (p≤0.01), whereas mutual interaction effect of BET, SS and FR was found to be non-significant ( p˃0.05). Conclusions: The results of this study demonstrated that the extrusion processing can be successfully explored to produce fatty meals with significant fatty acids retention for commercially food or feed purposes.

Fatty acid retention under temporally heterogeneous dietary intake in a cladoceran

Omega‐3 (ω3) and ‐6 (ω6) polyunsaturated fatty acids (PUFA) are essential for all aquatic animals, but their dietary availability can be highly heterogeneous in space and time. The way consumers retain PUFA across such heterogeneous feeding conditions remains poorly understood. In a series of feeding experiments, we investigated how retention efficiencies (i.e. amount in consumer biomass/amount ingested) of PUFA and bulk carbon responded to heterogeneous PUFA intake in Daphnia magna. Heterogeneous PUFA intake was achieved by exposing D. magna to algal diets of different PUFA content and composition for specific time periods. The retention efficiency of carbon did not change among dietary treatments. At shorter exposure to PUFA‐rich diet, retention efficiencies of most PUFA were 2–3 times higher than that of bulk carbon, clearly indicating PUFA bioaccumulation in D. magna. Increasing exposure to PUFA‐rich diet caused exponential decrease of retention efficiencies for most PUFA. However, D. magna receiving more PUFA were richer in these compounds despite lower retention efficiency. Eicosapentaenoic (20:5ω3) and arachidonic acid (20:4ω6) and their precursors were always supplied in the same proportions (3.6:1), but the 20:5ω3/20:4ω6 ratio in D. magna (an important measure of nutritional quality for consumers) increased with exposure time to these PUFA from 2.2:1 to 3.8:1, thus eventually matching the diet. Our results suggest that D. magna is an efficient gatherer, accumulator, and repository of PUFA under low/fragmented dietary availability. However, at higher availabilities, PUFA are not always bioaccumulated in D. magna. Hence, the efficiency of PUFA transfer by daphnids in food webs may depend on temporal PUFA availability and its range of variation. Finally, we show that heterogeneity in PUFA intake may also affect higher trophic levels by influencing nutritionally critical PUFA ratios of zooplankton.

Growth performance, feed utilisation and fatty acid deposition in Atlantic salmon, Salmo salar L., fed graded levels of high-lipid/high-EPA Yarrowia lipolytica biomass

Salmon aquaculture is currently reliant on fish oil as the major source of the very long chain (VLc) n−3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This report details the first study of an alternative source of EPA from the yeast Yarrowia lipolytica in feed for fish. Atlantic salmon was fed three dietary levels, 10% (Y10), 20% (Y20) and 30% (Y30) of a heat killed dried yeast biomass containing 6% EPA and 20% oil by weight for 95days. The yeast biomass was replacing fish meal, rapeseed oil and wheat meal in the diets. The increase in fish weight from 180 to 400g on the diets containing yeast, was comparable to groups fed control diets with either rapeseed oil (RO) or a mix of rapeseed and fish oil. The apparent digestibility coefficient for energy, protein and lipids, including n−3 fatty acids, decreased with increased inclusion of yeast biomass. Feed conversion ratio was higher, and energy retention lower, in the Y30 group than in the others. Protein retention was the lowest in the Y30 and FO groups followed by Y20. Fillet fatty acid composition reflected the higher ratio of EPA to DHA in the feeds added yeast. However, lower whole body retention of EPA, and higher retention of DPA (docosapentaenoic acid) and DHA, compared to average fatty acid retention, suggest that there had been some conversion of the EPA provided by the yeast into DPA (docosapentaenoic acid) and DHA in fish.

High dietary EPA does not inhibit ∆5 and ∆6 desaturases in Atlantic salmon (Salmo salar L.) fed rapeseed oil diets

Growth and fatty acid metabolism were studied in Atlantic salmon juveniles fed diets containing rapeseed oil (RO) enriched with 20:5n−3 (EPA) either alone or in combination with 22:6n−3 (DHA). Both fatty acids were added to the RO as highly concentrated triacylglycerols (TAGs). Diets containing RO or fish oil (FO) were used as controls. The salmon (start weight 103g) were kept in freshwater at 12°C, and the feeding experiment lasted for 109days. No differences in growth, feed conversion ratio (FCR) or nitrogen and energy retention were observed. The fatty acid analysis of total body lipids and the apparent fatty acid retention data, all strongly suggested that the salmon fed RO and RO+EPA converted more of the EPA to DHA than the salmon fed diets with relatively high levels of DHA (FO and RO+EPA+DHA). In all feeding groups the apparent retention of 22:5n−3 was high, suggesting an efficient C20 fatty acid elongase activity. These findings were further confirmed by the results from studies performed on hepatocyte cultures. The cells were isolated from the livers of salmon from the four feeding groups, and incubated with radio-labeled EPA. Significantly higher conversion of EPA to DHA was found both in the RO and RO+EPA group. When both EPA and DHA were added to the rapeseed oil diet, the total process of desaturation, elongations and beta-oxidation to DHA was significantly reduced (to about 50%). This is similar to what was observed in liver cells from the FO fed fish, strongly suggesting an inhibition by higher levels of DHA. Judging from the spectrum of radioactive labeled metabolites, the inhibition occurred mainly at the 24:5n−3 to 24:6n−3 (delta 6 desaturase) step, and most interestingly, at the 22:5n−3 to 24:5n−3 (second elongation) step. Further, gene expression measurements showed a significant inhibition of the genes for Δ5 and Δ6 desaturases by FO and RO+EPA+DHA feeding, and inhibition of the gene for elongase2 was also indicated. Thus, the results from this study reveal a high recovery of the n−3 fatty acid DPA (22:5n−3), and significant conversion to DHA when EPA is added to rapeseed oil based diets for salmon in freshwater.

Highly Unsaturated Fatty Acid (HUFA) Retention in the Freshwater Cladoceran, Moina macrocopa, Enriched With Lipid Emulsions

Fatty acid profiles of Moina macrocopa enriched with lipids from inexpensive squid or canola oil were compared with profiles of Moina enriched with a commercial enrichment diet, A1 DHA Selco® (ADS). Arachidonic acid (AA) significantly increased from &lt;0.01 to 0.28 mg/g body weight in Moina enriched with ADS at 1 g/l for 12 h and to 0.38 mg/g in Moina enriched in 2 g/l canola oil for 12 h. The highest increase in eicosapentaenoic acid (EPA; from 0.15 to 0.38 mg/g) was obtained when Moina were enriched in 1 g/l ADS for 12 h. The highest increases in docosahexaenoic acid (DHA; originally &lt;0.01) were obtained in Moina enriched in 1 g/l ADS for 12 h (increased to 0.09) or in 2 g/l ADS for 24 h (rose to 0.8 mg/g). The AA:EPA ratio was highest in Moina treated with 2 g/l canola oil for 12 h or 2 g/l squid oil for 24 h. The AA:DHA ratio was highest in Moina enriched with 2 g/l canola oil for 12 h while the DHA:EPA ratio was highest in Moina enriched with 2 g/l squid oil for 24 h.

Potential food sources of &lt;em&gt;Glycymeris nummaria&lt;/em&gt; (Mollusca: Bivalvia) during the annual cycle indicated by fatty acid analysis

Seasonal changes of food sources were investigated by analysing the fatty acid profiles of digestive gland and muscle tissues of the naturally occurring clams Glycymeris nummaria in Mali Ston Bay, Croatia. Total lipids in the digestive gland and the adductor muscle showed parallel changes, with a maximum after the main spawning event in September. In the digestive gland saturated fatty acids were highly dominant (up to 82%), indicating detritus as the main food source for this species. This type of food prevailed during the autumn/winter period, in contrast to the spring/summer period when detritus was enriched with phyto- and, to a lesser extent, zooplankton. Fatty acid composition of muscles indicated highly efficient utilization of ingested food through significant retention of polyunsaturated fatty acid from the clams’ diet during the entire period investigated.