Long term effects on performance physiology and fillet quality of Atlantic salmon (Salmo salar L.) fed low fish meal and n-3 LC-PUFA diets where fish oil was substituted by whole Schyzochytrium limacinum biomass
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ABSTRACT: Atlantic salmon individuals were grown, from fresh water to salt water in tanks on diets with low fish meal (10%) and 1-1.25% total n-3 LC-PUFA levels. Dietary n-3 LC-PUFAs were supplemented by 1) fish oil (FO), 2) Schyzochytrium limacinum biomass (AA). Further, the fish from all treatments were mixed and redistributed in sea cages reared to slaughter (ca. 3kg body weight) on either FO or AA. Transcriptomics analyses in liver and intestinal tissues revealed significant dietary effects on the expression of immune modulating, as well as ion, lipid, protein and xenobiotic metabolism genes.
Project description:In the context of replacing fish meal and fish oil in feeds for aquaculture, rainbow trout alevins received from first-feeding onwards, one of the three experimental diets: V (100% plant-based), C (mix of FM-FO & plant ingredients) or M (100% FM-FO based). The long term effects of such dietary replacement on the intestinal (mid gut) and hepatic transcriptome were studied in juveniles after a 7-month feeding trial at 7°C.
Project description:Currently, the only sustainable alternatives for dietary fish oil (FO) in aquafeeds are vegetable oils (VO) that are devoid of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). Entirely new sources of n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids through de novo production is a potential solution to fill the gap between supply and demand of these important nutrients. Camelina sativa,was metabolically engineered to produce a seed oil (ECO) with > 20 % EPA and its potential to substitute for FO in Atlantic salmon feeds was tested. Fish were fed one of three experimental diets containing FO, wild-type camelina oil (WCO) or ECO as the sole lipid sources for 7-weeks. Inclusion of ECO did not affect any of the performance parameters studied and enhanced apparent digestibility of individual n-6 and n-3 PUFA compared to dietary WCO. High levels of EPA were maintained in brain, liver and intestine (pyloric caeca), and levels of DPA and DHA were increased in liver and intestine of fish fed ECO compared to fish fed WCO likely due to increased LC-PUFA biosynthesis based on up-regulation of the genes. Fish fed WCO and ECO showed slight lipid accumulation within hepatocytes similar to that with WCO, although not significantly different to fish fed FO. The regulation of a small number of genes could be attributed to the specific effect of ECO (311 features) with metabolism being the most affected category. The EPA oil from transgenic Camelina (ECO) could be used as a substitute for FO, however it is a hybrid oil containing both FO (EPA) and VO (18:2n-6) fatty acid signatures that resulted in similarly mixed metabolic and physiological responses.
Project description:There is an increasing drive to replace fish oil (FO) in finfish aquaculture diets with vegetable oils (VO), driven by the short supply of FO derived from wild fish stocks. Little is known of the consequences for fish health after such substitution. The effect of dietary VO on hepatic gene expression was determined in Atlantic salmon (Salmo salar) byg a cDNA microarray analysis. Post-smolt farmed salmon were reared for x weeks on diets where the FO component of the feed was replaced with one of three different VOs - rapeseed (RO), soybean (SO) or linseed (LO). RNA from five fish fed on each diet was extracted. A total of 20 cDNA microarray hybridisations - TRAITS / SGP Atlantic salmon 17k feature cDNA microarray - were performed - 4 diets (three VO + FO control) x 5 individuals - using a common pooled reference control design. Data were obtained from 19 of the 20 hybridisations.
Project description:In this study, female S. argus were fed diets containing 8% fish oil (FO) or 8% soybean oil (SO) for 60 days. Proteomic analysis of liver tissue revealed significant changes in protein expression between the two dietary groups.
Project description:New de novo sources of omega 3 (n-3) long chain polyunsaturated fatty acids (LC-PUFA) are required as alternatives to fish oil in aquafeeds in order to maintain adequate levels of the beneficial fatty acids, eicosapentaenoic and docosahexaenoic (EPA and DHA, respectively). The present study investigated the use of an EPA+DHA oil derived from a transgenic Camelina sativa in feeds for Atlantic salmon (Salmo salar) containing low levels of fishmeal (35 %) and fish oil (10 %), reflecting current commercial formulations, to determine the impacts on intestinal transcriptome, tissue fatty acid profile and health of farmed salmon. Post-smolt Atlantic salmon were fed for 12-weeks with one of three experimental diets containing either a blend of fish oil/rapeseed oil (FO), wild-type camelina oil (WCO) or transgenic camelina oil (DCO) as added lipid source. The DCO diet did not affect any of the fish performance or health parameters studied. Analyses of the mid and hindgut transcriptomes showed only mild effects on metabolism. Flesh of fish fed the DCO diet accumulated almost double the amount of n-3 LC-PUFA than fish fed the FO or WCO diets, indicating that these oils from transgenic oilseeds offer the opportunity to increase the n-3 LC-PUFA in farmed fish to levels comparable to those found twelve years ago.
Project description:Gene expresion profiles from the scAT following 6 week LC n-3 PUFA and 6 week placebo supplementation were compared Women with PCOS were supplemented with 4g n-3 PUFA (containing 1.8g EPA and DHA) daily for 6 weeks and changes in subcutaneous adipose tissue gene expression was compared with 6 week placebo supplementation. This was a cross-over placebo, controlled dietary intervention wherein women with PCOS received both treatments.
Project description:Vegetable oils (VO) are possible substitutes for fish oil in aquafeeds but are limited by their lack of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). However, oilseed crops can be modified to produce n-3 LC-PUFA such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, representing a potential option to fill the gap between supply and demand of these important nutrients. Camelina sativa was metabolically engineered to produce a seed oil with around 15 % total n-3 LC-PUFA to potentially substitute for fish oil in salmon feeds. Post-smolt Atlantic salmon (Salmo salar) were fed for 11-weeks with one of three experimental diets containing either fish oil (FO), wild-type Camelina oil (WCO) or transgenic Camelina oil (DCO) as added lipid source to evaluate fish performance, nutrient digestibility, tissue n-3 LC-PUFA, and metabolic impact determined by liver transcriptome analysis. The DCO diet did not affect any of the performance or health parameters studied and enhanced apparent digestibility of EPA and DHA compared to the WCO diet. The level of total n-3 LC-PUFA was higher in all the tissues of DCO-fed fish than in WCO-fed fish with levels in liver similar to those in fish fed FO. Endogenous LC-PUFA biosynthetic activity was observed in fish fed both the Camelina oil diets as indicated by the liver transcriptome and levels of intermediate metabolites such as docosapentaenoic acid, with data suggesting that the dietary combination of EPA and DHA inhibited desaturation and elongation activities. Expression of genes involved in phospholipid and triacylglycerol metabolism followed a similar pattern in fish fed DCO and WCO despite the difference in n-3 LC-PUFA contents.
Project description:Facing a bottleneck in the growth of aquaculture, and a gap in the supply and demand of the highly beneficial omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), sustainable alternatives to the traditional feeds are much needed. Therefore, in this trial, an oil extracted from newly designed plant, Camelina sativa, was tested for its n-3 replacement capabilities, using three different groups of post-smolt Atlantic salmon (Salmo salar) which were fed for 12 weeks three experimental diets; a control diet containing a blend of fish oil (5 %) and rapeseed oil (15 %) (FO), a wild-type Camelina (20 %) (WCO) and the transgenic Camelina oil (20 %) (DCO), all of them having the same basal composition. By comparing them, an overall evaluation of fish performance, fatty acid profile, feeds digestibility and gene expression was done. In the context of the new transgenic diet, there were no negative effects on the growth, survival rate or health of the fish. The whole fish n-3 levels were highest in the DCO-fed fish with EPA+DHA levels almost double compared to FO-fed fish and more than double when compared to WCO-fed ones, clearly suggesting the efficiency of the Camelina oil in providing competitive levels of n-3 LC-PUFA compared to the commercial “gold standard”.
Project description:Novel DHA-enriched oils with high α-linolenic acid (ALA) content will be available in the near future as an alternative for dietary fish oil replacement in aquafeeds. As preliminary validation, we 1) assessed the ability of a diet containing a formulated oil blend (tuna oil + flaxseed oil, TOFX) with high DHA and ALA content to achieve fish oil-like omega-3 long-chain (≥C20) polyunsaturated fatty acids (n-3 LC-PUFA) tissue composition in Atlantic salmon smolts, and 2) applied liver proteomics as exploratory approach to understand the consequent nutritional changes. Comparisons were made on fish fed a fish oil-based diet (FO) and a commercial-like oil blend diet (fish oil + poultry oil, FOPO) over 89 days. Growth and feed efficiency ratio were lower on the TOFX diet. Fish tissue concentration of n-3 LC-PUFA and the n-3:n-6 ratio were significantly higher for TOFX than for FOPO, but not higher than for FO, while tissue retention efficiency of n-3 LC-PUFA was promoted by TOFX relative to FO. Proteomics analysis revealed an unexpected oxidative stress response as the main adaptive physiological mechanism in TOFX fish. While specific dietary fatty acid concentrations and balances and antioxidant supplementation may need further attention, the use of an oil with a high content of DHA and ALA can enhance tissue deposition of n-3 LC-PUFA in relation to a commercially used blend oil.