Replacement Of Fish Oil Research Articles

Fish oil from plants

Plant Science Human heart health benefits from a diet rich in the polyunsaturated fatty acids found in oily fish such as salmon and anchovies. Unfortunately, marine fisheries are increasingly fragile, and farm-raised salmon require expensive supplements to generate the desirable fatty acids. Ruiz-Lopez et al. engineered the oilseed crop plant Camelina into a source of the key fatty acids by plucking enzymes from sources as diverse as phytoplankton, microalgae, and oomycetes. Camelina expressing the transgenes made as much as a quarter of their seed lipids into replacements for fish oil, surpassing salmon, pound for pound, as a source of the right fatty acids. ![Figure][1] Widely grown Camelina sativa can be engineered to produce fish oil PHOTO: © BUITEN-BEELD/ALAMY Plant Biotechnol. J. 10.1111/pbi.12328 (2015). [1]: pending:yes

Effect of dietary fish oil replacement with palm oil on growth performance, hematology and liver anti-oxidative enzymes of juvenile Japanese flounder Paralichthys olivaceus (Temminck & Schlegel, 1846)

A 60-day feeding trial was conducted to evaluate the effects of dietary palm oil supplements on growth performances, hematology, liver anti-oxidative enzymes and air exposure resistance of Japanese flounder, Paralichthys olivaceus (initial weights 2.56 ± 0.01 g). Five diets were tested wherein the dietary fish oil was replaced by palm oil at: 0% (Control), 20% (20%), 40% (40%), 50% (50%) and 60% (60%). After the feeding trial, the 20% dietary palm oil was shown to provide similar growth rates and feed efficiency with no negative effects compared to the control group (P > 0.05). Significantly lower growth rates and feed utilization were found in fish fed higher than 40% palm oil in the diet (P < 0.05). Except for total serum protein, the blood parameters, liver anti-oxidative enzymes, stress resistance and proximate compositions of Japanese flounder were not altered, even with dietary palm oil up to 60% of the lipid source (P > 0.05). According to the present results, palm oil is a valuable lipid source substitute in Japanese flounder diets; around 20–40% fish oil can be replaced with palm oil with no negative effects.

The effect of total replacement of fish oil with DHA-Gold®and plant oils on growth and fillet quality of rainbow trout (Oncorhynchus mykiss) fed a plant-based diet

This study investigated the effect of the replacement of fish oil (FO) with DHA-Gold (DHA-G)-supplemented plant oils (PO) in rainbow trout fed plant-protein-based diets. Five diets (450 mg g−1 digestible protein and 150 mg g−1 crude lipid) were fed to rainbow trout (initial weight 37 ± 0.5 g) for 12 weeks in a 15 °C recirculating water system. The lipid inclusion types and levels were FO, PO and PO with DHA-G supplemented at 30 mg g−1, 60 mg g−1 or 90 mg g−1 of the diet replacement for corn oil. Fish fed 90 mg g−1 DHA-G were significantly larger and consumed more feed than fish-fed PO or FO (218 g and 2.6% bwd−1 versus 181 g and 2.4% and 190 g and 2.3%, respectively). Feed conversion ratio was significantly increased in fish fed 90 mg g−1 DHA-G (0.99) as compared to fish-fed FO (0.90) and 30 mg g−1 DHA-G (0.91). Panellists found trout fillets from fish fed the 90 mg g−1 DHA-G diet to have significantly fishier aroma and flavour than fish fed the FO diet. Fatty acid analysis demonstrated that 60 mg g−1 or 90 mg g−1 DHA-G supplementation increased PO fed fish fillet DHA to fatty acid levels equivalent or higher than those fish fed a FO diet.

A new strain of docosahexaenoic acid producing microalga from Malaysian coastal waters

Thraustochytrids are marine protists belonging to the class Labyrinthula of the kingdom Chromista. This group of microbes is considered a promising alternative source of high-valued omega-3 oils, especially docosahexaenoic acid (DHA, C22:6n3), replacing fish oil which is the current major source of DHA and eicosapentaenoic acid (EPA, C20:5n3). Our new isolate, SW1, was considered to be an Aurantiochytrium based on its morphology, fatty acid profile and molecular phylogenetic analysis. Microscopic observations revealed that SW1 has high similarity to Aurantiochytrium limacinum ATCC MYA-1381 (SR21), possessing spherical vegetative cells which undergo repeated bipartition to form diads, tetrads, octads and zoosporangia that release motile zoospores. When cultivated in four different media, SW1 produced the highest biomass (13.17g/L) and DHA (3.6g/L) in a medium composed of glucose, sea salt, monosodium glutamate (MSG) and yeast extract. Visualization of lipid droplet development in SW1 using Sudan Black B dye revealed that lipid droplets enlarge to occupy almost the entire cell volume within 72 to 96h of cultivation. This strain was also found to be able to utilize various saccharides as carbon source. The results of this study show that Aurantiochytrium sp. SW1 is a potential candidate to be developed as commercial microbial DHA producer.

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.

Growth performance and quality traits of European sea bass (D. labrax) fed diets including increasing levels of freeze-dried Isochrysis sp. (T-ISO) biomass as a source of protein and n-3 long chain PUFA in partial substitution of fish derivatives

Abstract The aim of this study was to evaluate nutrient digestibility, growth performance, biometry, dressing out parameters, fillet muscle proximate and fatty acid composition of European sea bass ( Dicentrarchus labrax L.) of nearly marketable size, fed increasing levels of a freeze-dried biomass of Isochrysis sp. (clone T-ISO) as a partial substitute for protein and lipid from fish derivatives, in diets where the level of n-3 long chain (LC) PUFA were reduced through a partial replacement of fish oil for crude palm oil. Since diets including the test ingredients could possibly result in changes of certain quality attributes, fish were also subjected to overall sensory evaluation by a trained panel of assessors according to a triangle test. Three diets were formulated to be grossly iso -nitrogenous (N, 7.5% dry matter). A preparation in which fish meal/trimmings and fish oil were the major protein and lipid sources was used as a positive control diet. Two test complete diets were obtained from the control preparation so that approximately 10 and 20% crude protein from a high quality fish meal and 18 and 36% lipids from fish oil were supplied by the dried microalgae biomass. To stress the role of Isochrysis sp. as a source of n-3(LC)PUFA, the diets including increasing levels of the microalgae biomass were made grossly iso -caloric–lipidic by replacing a part of fish oil with palm oil which is known to be virtually free from n-3 PUFA. Each diet was fed to apparent satiety to quadruplicate groups of sea bass (142 g) over 121 days. The results have shown that replacing up to 20% crude protein from fish meal with a dried Isochrysis biomass and up to 36% fish lipid for those supplied by the microalgae in a diet with reduced level of fish oil, did not adversely affect feed intake or growth performance relative to controls even if the highest substitution rate resulted in a decline (P

Intake of farmed Atlantic salmon fed soybean oil increases hepatic levels of arachidonic acid-derived oxylipins and ceramides in mice

Introduction of vegetable ingredients in fish feed has affected the fatty acid composition in farmed Atlantic salmon (Salmo salar L). Here we investigated how changes in fish feed affected the metabolism of mice fed diets containing fillets from such farmed salmon. We demonstrate that replacement of fish oil with rapeseed oil or soybean oil in fish feed had distinct spillover effects in mice fed western diets containing the salmon. A reduced ratio of n-3/n-6 polyunsaturated fatty acids in the fish feed, reflected in the salmon, and hence also in the mice diets, led to a selectively increased abundance of arachidonic acid in the phospholipid pool in the livers of the mice. This was accompanied by increased levels of hepatic ceramides and arachidonic acid-derived pro-inflammatory mediators and a reduced abundance of oxylipins derived from eicosapentaenoic acid and docosahexaenoic acid. These changes were associated with increased whole body insulin resistance and hepatic steatosis. Our data suggest that an increased ratio between n-6 and n-3-derived oxylipins may underlie the observed marked metabolic differences between mice fed the different types of farmed salmon. These findings underpin the need for carefully considering the type of oil used for feed production in relation to salmon farming.

A nutritionally-enhanced oil from transgenic Camelina sativa effectively replaces fish oil as a source of eicosapentaenoic acid for fish.

For humans a daily intake of up to 500 mg omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) is recommended, amounting to an annual requirement of 1.25 million metric tonnes (mt) for a population of 7 billion people. The annual global supply of n-3 LC-PUFA cannot meet this level of requirement and so there is a large gap between supply and demand. The dietary source of n-3 LC-PUFA, fish and seafood, is increasingly provided by aquaculture but using fish oil in feeds to supply n-3 LC-PUFA is unsustainable. Therefore, new sources of n-3 LC-PUFA are required to supply the demand from aquaculture and direct human consumption. One approach is metabolically engineering oilseed crops to synthesize n-3 LC-PUFA in seeds. Transgenic Camelina sativa expressing algal genes was used to produce an oil containing n-3 LC-PUFA to replace fish oil in salmon feeds. The oil had no detrimental effects on fish performance, metabolic responses or the nutritional quality of the fillets of the farmed fish.

Seaweed enrichment of feed supplied to farm‐raised Atlantic salmon (Salmo salar) is associated with higher total fatty acid and LC n‐3 PUFA concentrations in fish flesh

AbstractSeaweeds have great potential as feed ingredients for fish farming, though their effects on the fatty acid content and profile of fish flesh are not well established. Recent studies suggest that seaweed supplementation can increase the concentration of long chain omega‐3 PUFA (LC n‐3 PUFAs) in various animal species, though this effect has never been assessed in salmon. Primarily, this study compared the fatty acid profiles of Atlantic salmon (Salmo salar) that were fed a high quality diet containing seaweed (Diet A), with those on a high quality control diet without seaweed (Diet B). In addition, fatty acid profiles of Atlantic salmon that were fed a standard industrial quality diet containing seaweed (Diet C), were compared to those on a similar diet without seaweed (Diet D). Total fatty acid concentrations were significantly higher (+30%, p&lt;0.05) in the flesh of the fish that were fed seaweed. Flesh concentrations of eicosapentaenoic acid (EPA) and DHA were 30% and 62% higher (p&lt;0.05) in Diet A and Diet C groups compared to salmon in Diet B and Diet D groups respectively. Analysis of the fish lipid revealed no significant differences in LC‐3 PUFAs between the high quality diet groups, while significantly higher (+ 45%, p&lt;0.005) concentrations EPA + DHA were found in fish that consumed Diet C compared to Diet D. These findings support the hypothesis that the inclusion of seaweed in fish farm diets alters lipid partitioning and profiles of Atlantic salmon.Practical Applications: This study reveals a possible way to substantially increase EPA and DHA concentrations in farmed salmon. Both EPA and DHA are LC n‐3 PUFAs and are essential components of the human diet. Unfortunately, consumption of such PUFAs is generally below RDI levels, which is in turn linked to several non‐communicable diseases. Moreover, EPA + DHA concentrations in farmed salmon are now declining due to the replacement of scarce fish oils (rich in LC n‐3 PUFA) by more sustainable plant‐based oils (low in EPA + DHA) in fish feeds. Since salmon is one of the world's most consumed fish and one of the few major sources of LC n‐3 PUFAs, it is of great importance to maintain or increase EPA + DHA levels in farmed salmon. The results of this study show that this could be achieved by dietary inclusion of seaweed.Seaweed can increase LC n‐3 PUFA levels in salmon.

Effect of replacing dietary fish oil with soybean oil on growth performance, fatty acid composition and haematological parameters of juvenile meagre,Argyrosomus regius

A nutrition trial with meagre, Argyrosomus regius was assessed to determine the effect of dietary replacement of fish oil (FO) by soybean oil (SO) on the growth, feed utilization, body composition, fatty acid composition and basic haematological parameters. Six isonitrogenous (47% crude protein) and isoenergetic (gross energy 22 kJ/g) experimental diets were formulated by replacing 0 (FO), 20 (S20), 40 (S40), 60 (S60), 80 (S80) and 100 (S100) % of the FO with SO. Fish were fed three times daily to near satiation for 14 weeks. The specific growth rate (SGR) of fish fed S100 diet was significantly lower than the other treatments, except SO80 diet. The fish fed SO100 diet displayed significantly higher feed conversion ratio than that of other diets (P < 0.05). It was observed that fish fed the SO100 and SO80 diets displayed haemoglobin (HGB) levels significantly lower (P < 0.05) than fish fed the SO20 diet. Packed cell volume (PCV) of fish fed SO20 diet was significantly higher compared to SO100. The white blood cell (WBC) and red blood cell (RBC) remained unaffected by dietary treatment. The docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) levels of meagre were significantly reduced by the substituting of dietary SO by FO at the end of the feeding period. The level of linoleic acid (18:2n-6, LA) and linolenic acid (18:3n-3, LNA) significantly raised in fish fed with SO diets (P < 0.05). The results of this study showed that SO could be replaced FO up to 80% in meagre diet without negative effect on growth performance and basic haematological parameters. Furthermore, the maximum level of FO replacement with SO determined by second order polynomial regression analysis, was 30.1% on the basis of maximum SGR.

Omega-3 long-chain polyunsaturated fatty acids and aquaculture in perspective

In the 40years since the essentiality of polyunsaturated fatty acids (PUFA) in fish was first established by determining quantitative requirements for 18:3n−3 and 18:2n−6 in rainbow trout, essential fatty acid (EFA) research has gone through distinct phases. For 20years the focus was primarily on determining qualitative and quantitative EFA requirements of fish species. Nutritional and biochemical studies showed major differences between fish species based on whether C18 PUFA or long-chain (LC)-PUFA were required to satisfy requirements. In contrast, in the last 20years, research emphasis shifted to determining “optimal” levels of EFA to support growth of fish fed diets with increased lipid content and where growth expectations were much higher. This required greater knowledge of the roles and functions of EFA in metabolism and physiology, and how these impacted on fish health and disease. Requirement studies were more focused on early life stages, in particular larval marine fish, defining not only levels, but also balances between different EFAs. Finally, a major driver in the last 10–15years has been the unavoidable replacement of fish oil and fishmeal in feeds and the impacts that this can have on n−3 LC-PUFA contents of diets and farmed fish, and the human consumer. Thus, dietary n−3 in fish feeds can be defined by three levels. Firstly, the minimum level required to satisfy EFA requirements and thus prevent nutritional pathologies. This level is relatively small and easy to supply even with today's current high demand for fish oil. The second level is that required to sustain maximum growth and optimum health in fish being fed modern high-energy diets. The balance between different PUFA and LC-PUFA is important and defining them is more challenging, and so ideal levels and balances are still not well understood, particularly in relation to fish health. The third level is currently driving much research; how can we supply sufficient n−3 LC-PUFA to maintain these nutrients in farmed fish at similar or higher levels than in wild fish? This level far exceeds the biological requirements of the fish itself and to satisfy it we require entirely new sources of n−3 LC-PUFA. We cannot rely on the finite and limited marine resources that we can sustainably harvest or efficiently recycle. We need to produce n−3 LC-PUFA de novo and all possible options should be considered.

Use of Plant Products as Candidate Fish Meal Substitutes: An Emerging Issue in Aquaculture Productions

The search for new dietary ingredients for total or partial replacement of fish oil has assumed a growing importance and is currently the subject of advanced scientific research. Plants are recognized to be a good source of both peptides and oils for fish aquafeeds. The present paper reviews the effects played on fish growth and physiology by some plant products, highlighting also their possible detrimental effects related to the presence of anti-nutritional factors. Although complete replacement of fish meal in feeds for cultured species is still difficult, the results obtained by the current studies performed on plant products are promising and encourage further research on this issue.

Dietary ALA, But not LNA, Increase Growth, Reduce Inflammatory Processes, and Increase Anti‐Oxidant Capacity in the Marine Finfish Larimichthys crocea

Whilst aquaculture feed is increasingly formulated with the inclusion of plant oils replacing fish oil, and increasing research effort has been invested in understanding the metabolic effects of reduced dietary n-3 long chain poly unsaturated fatty acids (n-3 LC-PUFA), relatively little information is available on the potential direct metabolic roles of dietary alpha-linolenic acid (ALA, 18:3n-3) and alpha-linolenic acid/linoleic acid (LNA, 18:2n-6) ratio in cultured marine finfish species. In this study, four plant oil based diets, with varying ALA/LNA ratio (0.0, 0.5, 1.0 and 1.5) were fed to juvenile large yellow croakers (Larimichthys crocea) and compared to a fish oil-based control diet (CD) to evaluate the resulting effects on growth, nonspecific immunity, anti-oxidant capacity and related gene expression. High dietary LNA negatively impacted fish growth performance, nonspecific immunity and antioxidant capacity, but growth and immunity were maintained to levels comparable to CD by increasing the ratio of dietary ALA/LNA. The over-expression of genes associated with inflammation (cyclooxygenase-2 and interleukin-1β) and fatty acid oxidation (carnitine palmitoyl transferase I and acyl CoA oxidase) in croakers fed high concentrations of LNA were reduced to levels comparable to those fed CD by increasing dietary ALA/LNA. This study showed that dietary ALA, by increasing the overall n-3/n-6 PUFA ratio, exerts direct anti-inflammatory and antioxidant effects, similar to those exerted by dietary n-3 LC-PUFA.

Fish oil replacement by soybean oil in the diet of fat snook juveniles

The objective of this work was to evaluate fish oil replacement by soybean oil in diets, as for the effects on the performance and body composition of juveniles of fat snook (Centropomus parallelus). The experiment was carried out in a randomized block design, with three treatments (lipid sources) and six replicates, in a 60-day period. Fat snook juveniles (24.17±0.28g) were distributed in 18 experimental tanks of 200 L each, equipped with aeration and heating systems, under continuous water renovation (800% per day). Three isoproteic (44% CP) and isoenergetic (4,635 kcal CE kg-1) diets were formulated to comprise three replacement rates (0, 50, and 100%) of fish oil by soybean oil. Biometric analyses were done to evaluate fish performance, and two entire specimens from each replicate were used for body composition analyses. The zootechnical indices of weight gain (38.68±5.41 g), feed conversion (1.38±0.10), and specific growth at 1.70±0.18% weight gain per day were considered satisfactory. Lipid source substitution does not affect the performance and body composition of fat snook juveniles, which suggests that soybean oil can replace fish oil in diet formulation.

Schizochytriumas a replacement for fish oil in a fishmeal free diet for jade perch,Scortum barcoo(McCulloch &amp; Waite)

A 10-week trial was conducted to determine the response of juvenile jade perch Scortum barcoo on the replacement of dietary fish oil (FO) in a fishmeal free diet. Three iso-nitrogenous, isocaloric and isolipidic diets were formulated, each containing a different primary fat source: FO, linseed oil (LO), and a mixture of Schizochytrium and LO. The substitution of FO with the mixture of Schizochytrium and LO did not cause a difference in growth. However, there was an 8% reduction in weight gain in fish fed dietary LO, indicating that juvenile jade perch do require a minimal concentration of dietary n-3 highly unsaturated fatty acids (HUFA). Fish fed the Schizochytrium diet stored more efficient n-3 HUFA and in particular DHA in their flesh, and retained a higher fillet recovery compared to fish fed FO. In addition, we demonstrated that jade perch are able to produce both n-3 HUFA and n-6 HUFA when dietary PUFA are present. Fish fed the LO diet for 10 weeks contained the lowest amount of n-3 HUFA in fillets among dietary treatment groups. However, feeding these fish the Schizochytrium diet for an additional 4 weeks increased the n-3 HUFA content towards the same concentration of n-3 HUFA found in the flesh of fish fed FO, without affecting the sensory properties of the fillets. In contrary, feeding the Schizochytrium diet for a continuous period of 14 weeks lowered overall sensory property scores.

Dietary n-6/n-3 LC-PUFA ratio, temperature and time interactions on nutrients and fatty acids digestibility in Atlantic salmon

Abstract The objective of the present study was to evaluate the effects of altered dietary n-3/n-6 LC-PUFA ratio, adaptation to diet over time, different water temperatures, and their interactions on nutrients and fatty acids digestibility in juvenile Atlantic salmon. Three experimental diets were formulated to be identical, with the only exception of the ratio of eicosapentaenoic acid (EPA, 20:5n-3) to arachidonic acid (ARA, 20:4n-6), and fed to triplicate groups of juvenile Atlantic salmon ( Salmo salar ) of 55 g initial body weight. Fish were reared in a fully controlled recirculating aquaculture system, fed to apparent satiety twice daily and kept at 10 °C and for an initial period of 100 days, and faeces were collected for digestibility estimation. Then, half of the fish of each experimental tank were moved to a separate system, where the water temperature was gradually increased up to 20 °C. Fish were maintained in the two systems for an additional period of 50 days, and faeces were collected for digestibility estimation from both groups of fish at the two water temperatures. This study concluded that dietary treatments and time had only minor effects, whereas environmental temperature resulted in modified digestibility values, with increased nutrient digestibility with increasing temperature. Varying EPA/ARA ratio in the diet had only minor direct effects on digestibility, with no direct effect on overall nutrients digestibility, and fundamentally only statistically significant effects in the fatty acid digestibility of EPA and ARA themselves. Because of current increasing pressure for more efficient fish oil replacement strategies, increasing interest in dietary ARA in aquafeed and increasing relevance and occurrence of sub-optimal rearing temperature in commercial aquaculture, this study can be considered to be important as it provided a series of fundamental information, which are envisaged to be useful towards addressing these constraints and possible nutritional remedial strategies.

Effects of fish oil replacement by a vegetable oil blend on digestibility, postprandial serum metabolite profile, lipid and glucose metabolism of European sea bass (Dicentrarchus labrax) juveniles

Effects of fish oil replacement by a vegetable oil blend on digestibility, postprandial serum metabolite profile, lipid and glucose metabolism of European sea bass (<i>Dicentrarchus labrax</i>) juveniles

Effects of dietary fish oil replacement by microalgae raw materials on growth performance, body composition and fatty acid profile of juvenile olive flounder,Paralichthys olivaceus

Replacing dietary fish oil with DHA-rich microalgae Schizochytrium sp. and EPA-rich microalgae Nannochloropsis sp. for olive flounder (Paralichthys olivaceus) was examined. Three experimental isonitrogenous and isolipidic diets with lipid source provided by 50% fish oil (F50S50), 50% (M50F25S25) and 100% microalgae raw material (M100) respectively were compared with a soybean oil (S100) diet as control. Triplicate groups of olive flounder juveniles (16.5 ± 0.91 g) were fed the experimental diets, and a group was fed the control diets for 8 weeks in a recirculation system. Results showed feed efficiency and growth performance were not significantly changed when fish oil (FO) was totally substituted by soybean oil (SO) or microalgae raw material (MRM). The whole-body composition, lipid content of liver and muscle, and lipid composition of plasma were not significantly influenced by the total substitution of FO by MRM. The polyunsaturated fatty acids (PUFA) content of muscle and liver declined in fish fed S100 diet, whereas it was not significantly reduced in fish fed M50F25S25 and M100 diets. The total substitution of FO by MRM not only maintained the levels of arachidonic acid, EPA or DHA but also increased n-3/n-6 ratio. In conclusion, MRM as the sole lipid source is sufficient to obtain good feed efficiency, growth performance and human health value in olive flounder juveniles.

Evaluation of the impact of camelina oil-containing diets on the expression of genes involved in the innate anti-viral immune response in Atlantic cod (Gadus morhua)

To improve sustainability of aquaculture, especially for carnivorous species like Atlantic cod, replacement of fish oil-based diets with vegetable oil-based diets has been studied. The use of vegetable oil in fish feeds can significantly change the fatty acid composition of fish tissues, and given the importance of fatty acids in inflammation and immunity, this change could potentially impact the immune response and health of the fish. The oilseed Camelina sativa is a promising source for this vegetable oil, because of the high oil content of its seeds (40%), a higher n-3 fatty acid content than most other oilseeds, and a high amount of γ-tocopherol. This study aims to investigate the effect of the replacement of dietary fish oil with oil from Camelina sativa on the immune response of Atlantic cod, as measured by the gene expression in spleen.Juvenile cod were fed on a fish oil-based diet (FO) or one of two diets in which camelina oil replaced 40% or 80% of fish oil (40CO and 80CO respectively) for 67 days, after which they were injected with either the viral mimic polyriboinosinic polyribocytidylic acid (pIC), or phosphate-buffered saline (PBS) as a control. Microarray analysis was used to determine the effect of the diet on the basal spleen transcriptome (pre-injection), and on the response to pIC (24 h post-injection). No marked differences in the spleen transcriptome were found between the three diets, either before or after injection with pIC. All fish, regardless of diet, showed a strong anti-viral response 24 h after pIC injection, with more than 500 genes having a significant difference of expression of 2-fold or higher compared to the PBS-injected fish for the FO, 40CO and 80CO diets. Gene Ontology annotation analysis of the three pIC-responsive gene lists indicated they were highly similar, and that the term ‘immune system process’ was significantly enriched in the pIC-responsive gene lists for all three diets. QPCR analysis for 5 genes with a known function in the anti-viral innate immune response (LGP2, STAT1, IRF1, ISG15 and viperin) showed modestly (smaller than 2-fold) up-regulated basal expression of LGP2, IRF1 and STAT1 in fish fed 40CO compared to the other diets. After pIC injection, all 5 genes were significantly and strongly up-regulated in pIC-injected fish compared to PBS-injected fish, but no significant differences were found between any of the diets.In conclusion, replacement of up to 80% of fish oil with camelina oil in Atlantic cod diets does not have a strong effect on basal spleen gene expression. Atlantic cod fed on camelina oil-containing diets are capable of mounting a strong anti-viral immune response, which is comparable to that in cod fed with a fish oil diet.

Use of camelina oil to replace fish oil in diets for farmed salmonids and Atlantic cod

Abstract In this study growth and lipid composition of Atlantic salmon, rainbow trout and Atlantic cod were compared after feeding a diet containing camelina oil (CO) as a full replacement of fish oil (FO). CO is an interesting candidate for replacement due to its high total lipid content (40%) and a high amount of the ω3 precursor, 18:3ω3; high levels of mono- and polyunsaturated fatty acids, as well as significant amounts of γ-tocopherol, a potent antioxidant. Diets were formulated to meet the nutritional requirements for each species, and either contained FO or CO as the main lipid source. Three separate experiments were conducted (triplicate tanks for FO and CO): Atlantic salmon (mean initial weight 242 ± 46 g) were fed experimental diets for 16 weeks in seawater at 14 °C, rainbow trout (44.9 ± 10 g) were fed for 12 weeks in freshwater at 14 °C, and Atlantic cod (14.4 ± 1.6 g) were fed for 13 weeks at 10 °C. Growth performance of Atlantic cod was significantly affected by dietary CO in comparison to cod fed the FO diet (p