Metabolism, health and fillet nutritional quality in Atlantic salmon (Salmo salar) fed diets containing n-3-rich microalgae

AbstractMicroalgae, as primary producers of EPA and DHA, are among the most prominent alternative sources to fish oil for n-3 long-chain PUFA in animal and human nutrition. The present study aimed to assess technical, nutritional and fish health aspects of producing n-3-rich Atlantic salmon (Salmo salar) fish fillets by dietary supplementation of increasing levels of a DHA-producing Schizochytrium sp. and reduced or without use of supplemental fish oil. Atlantic salmon smolt were fed diets with graded levels of microalgae for 12 weeks, during which all fish showed high feed intake rates with postprandial plasma leptin levels inversely correlating with final mean fish body weights. Fish performance was optimal in all experimental treatments (thermal growth coefficient about 4·0 and feed conversion ratio 0·8–0·9), protein digestibility was equal in all diets, whereas dietary lipid digestibility inversely correlated with the dietary levels of the SFA 16 : 0. Fillet quality was good and similar to the control in all treatments in terms of n-3 long-chain PUFA content, gaping, texture and liquid losses during thawing. Histological fluorescence staining and immunofluorescence analysis of salmon intestines (midgut: base of intestine and villi) revealed significant effects on slime, goblet cell production and inducible nitric oxide synthase (iNOS) activity with increasing levels of dietary Schizochytrium sp. supplementation. Microarray analysis did not reveal any signs of toxicity, stress, inflammation or any other negative effects from Schizochytrium sp. supplementation in diets for Atlantic salmon.

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Oil from transgenic Camelina sativa containing over 25 % n-3 long-chain PUFA as the major lipid source in feed for Atlantic salmon (Salmo salar)

British Journal Of Nutrition ◽

10.1017/s0007114518001125 ◽

2018 ◽

Vol 119 (12) ◽

pp. 1378-1392 ◽

Cited By ~ 18

Author(s):

Mónica B. Betancor ◽

Keshuai Li ◽

Valentin S. Bucerzan ◽

Matthew Sprague ◽

Olga Sayanova ◽

...

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Supply And Demand ◽

Camelina Sativa ◽

Genetically Engineered ◽

Oilseed Crop ◽

Camelina Oil ◽

Chain Pufa ◽

Lipid Source ◽

Long Chain

AbstractFacing a bottleneck in the growth of aquaculture, and a gap in the supply and demand of the highly beneficial n-3 long-chain PUFA (LC-PUFA), sustainable alternatives to traditional marine-based feeds are required. Therefore, in the present trial, a novel oil obtained from a genetically engineered oilseed crop, Camelina sativa, that supplied over 25 % n-3 LC-PUFA was tested as a sole dietary-added lipid source in Atlantic salmon (Salmo salar) feed. Three groups of fish were fed three experimental diets for 12 weeks with the same basal composition and containing 20 % added oil supplied by either a blend of fish oil and rapeseed oil (1:3) (COM) reflecting current commercial formulations, wild-type Camelina oil (WCO) or the novel transgenic Camelina oil (TCO). There were no negative effects on the growth, survival rate or health of the fish. The whole fish and flesh n-3 LC-PUFA levels were highest in fish fed TCO, with levels more than 2-fold higher compared with those of fish fed the COM and WCO diets, respectively. Diet TCO had no negative impacts on the evaluated immune and physiological parameters of head kidney monocytes. The transcriptomic responses of liver and mid-intestine showed only mild effects on metabolism genes. Overall, the results clearly indicated that the oil from transgenic Camelina was highly efficient in supplying n-3 LC-PUFA providing levels double that obtained with a current commercial standard, and similar to those a decade ago before substantial dietary fishmeal and oil replacement.

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Dietary Lipid Effects on Gut Microbiota of First Feeding Atlantic Salmon (Salmo salar L.)

Frontiers in Marine Science ◽

10.3389/fmars.2021.665576 ◽

2021 ◽

Vol 8 ◽

Author(s):

Eleni Nikouli ◽

Konstantinos Ar. Kormas ◽

Yang Jin ◽

Yngvar Olsen ◽

Ingrid Bakke ◽

...

Keyword(s):

16S Rrna ◽

Atlantic Salmon ◽

Gut Microbiota ◽

Fish Oil ◽

Salmo Salar ◽

Vegetable Oil ◽

Early Life ◽

Dietary Lipid ◽

Rrna Gene ◽

First Feeding

Decline in fish oil and fish meal availability has forced the aquaculture sector to investigate alternative and sustainable aquafeed ingredients. Despite that several studies have evaluated the effect of fish oil replacement in aquaculture fish species, there is a knowledge gap on the effects of alternative dietary lipid sources on the gut microbiota in early life stages of Salmo salar. The present study evaluated the influence of dietary administration of two different lipid sources (fish oil and vegetable oil) on the intestinal microbiota of first feeding Atlantic salmon (S. salar) up to 93 days post first feeding (dpff). The two diets used in this study, FD (fish oil diet) and VD (blend of rapeseed, linseed and palm oils diet), were formulated to cover the fish nutritional requirements. Apart from the lipid source, the rest of the feed components were identical in the two diets. Hindgut samples were collected at 0, 35, 65, and 93 dpff. Moreover, fertilized eggs, yolk sac larvae, rearing water and feed were also collected in order to assess a possible contribution of their microbiota to the colonization and bacterial succession of the fish intestines. To analyze the bacterial communities, amplicon sequencing was used targeting the V3–V4 region of the 16S rRNA gene. The findings indicate that feeding on either fish oil or vegetable oil-based diet, fish growth variables (mean wet weight and total length) did not differ significantly during the experiment (p > 0.05). No significant differences were also found between the two dietary groups, regarding their gut bacteria composition, after the analysis of the 16S rRNA sequencing data. Instead, gut microbiota changed with age, and each stage was characterized by different dominant bacteria. These operational taxonomic units (OTUs) were related to species that provide different functions and have been isolated from a variety of environments. The results also show little OTUs overlap between the host and rearing environment microbiota. Overall, this study revealed the occurrence of a core microbiota in early life of Atlantic salmon independent of the feed-contained oil origin.

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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

Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology ◽

10.1016/j.cbpb.2006.10.099 ◽

2007 ◽

Vol 146 (2) ◽

pp. 197-206 ◽

Cited By ~ 63

Author(s):

Matthew R. Miller ◽

Peter D. Nichols ◽

Chris G. Carter

Keyword(s):

Fatty Acid ◽

Atlantic Salmon ◽

Fish Oil ◽

Salmo Salar ◽

Stearidonic Acid ◽

Chain Polyunsaturated Fatty Acid ◽

Omega 3 ◽

Dietary Fish ◽

Long Chain ◽

Atlantic Salmon Parr

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Endogenous biosynthesis of n-3 long-chain PUFA in Atlantic salmon

British Journal Of Nutrition ◽

10.1017/s0007114519000473 ◽

2019 ◽

Vol 121 (10) ◽

pp. 1108-1123 ◽

Cited By ~ 4

Author(s):

Thomas S. Mock ◽

David S. Francis ◽

Matthew K. Jago ◽

Brett D. Glencross ◽

Richard P. Smullen ◽

...

Keyword(s):

Atlantic Salmon ◽

Fish Oil ◽

Substantial Reduction ◽

Chain Pufa ◽

Endogenous Production ◽

Dietary Fish ◽

Pufa Biosynthesis ◽

Resultant Effect ◽

Long Chain

AbstractA more efficient utilisation of marine-derived sources of dietary n-3 long-chain PUFA (n-3 LC PUFA) in cultured Atlantic salmon (Salmo salar L.) could be achieved by nutritional strategies that maximise endogenous n-3 LC PUFA synthesis. The objective of the present study was to quantify the extent of n-3 LC PUFA biosynthesis and the resultant effect on fillet nutritional quality in large fish. Four diets were manufactured, providing altered levels of dietary n-3 substrate, namely, 18 : 3n-3, and end products, namely, 20 : 5n-3 and 22 : 6n-3. After 283 d of feeding, fish grew in excess of 3000 g and no differences in growth performance or biometrical parameters were recorded. An analysis of fatty acid composition and in vivo metabolism revealed that endogenous production of n-3 LC PUFA in fish fed a diet containing no added fish oil resulted in fillet levels of n-3 LC PUFA comparable with fish fed a diet with added fish oil. However, this result was not consistent among all treatments. Another major finding of this study was the presence of abundant dietary n-3 substrate, with the addition of dietary n-3 end product (i.e. fish oil) served to increase final fillet levels of n-3 LC PUFA. Specifically, preferential β-oxidation of dietary C18n-3 PUFA resulted in conservation of n-3 LC PUFA from catabolism. Ultimately, this study highlights the potential for endogenous synthesis of n-3 LC PUFA to, partially, support a substantial reduction in the amount of dietary fish oil in diets for Atlantic salmon reared in seawater.

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Effect of feeding Atlantic salmon (Salmo salar L.) a diet enriched with stearidonic acid from parr to smolt on growth and n-3 long-chain PUFA biosynthesis

British Journal Of Nutrition ◽

10.1017/s0007114510005714 ◽

2011 ◽

Vol 105 (12) ◽

pp. 1772-1782 ◽

Cited By ~ 19

Author(s):

Mohamed B. Codabaccus ◽

Andrew R. Bridle ◽

Peter D. Nichols ◽

Chris G. Carter

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Docosapentaenoic Acid ◽

Stearidonic Acid ◽

Eicosatetraenoic Acid ◽

Biosynthetic Activity ◽

Chain Pufa ◽

Consumer Perspective ◽

Pufa Biosynthesis ◽

Long Chain

Vegetable oils (VO) have become the predominant substitute for fish oil (FO) in aquafeeds; however, the resultant lower content of n-3 long-chain ( ≥ C20) PUFA (n-3 LC-PUFA) in fish has put their use under scrutiny. The need to investigate new oil sources exists. The present study tested the hypothesis that in Atlantic salmon (Salmo salar L.), a high intake of stearidonic acid (SDA) from Echium oil (EO) would result in increased n-3 LC-PUFA biosynthesis due to a lower requirement for Δ6 desaturase. Comparisons were made with fish fed on diets containing rapeseed oil (RO) and FO in freshwater for 112 d followed by 96 d in seawater. EO fish had higher whole-carcass SDA and eicosatetraenoic acid (ETA) in freshwater and prolonged feeding on the EO diet in seawater resulted in higher SDA, ETA, EPA and docosapentaenoic acid (DPA) compared with RO fish. Fatty acid mass balance of freshwater fish indicated higher biosynthesis of ETA and EPA in EO fish compared with fish fed on the other diets and a twofold increase in n-3 LC-PUFA synthesis compared with RO fish. In seawater, n-3 biosynthetic activity was low, with higher biosynthesis of ETA in EO fish and appearance of all desaturated and elongated products along the n-3 pathway. SDA-enriched VO are more suitable substitutes than conventional VO from a human consumer perspective due to the resulting higher SDA content, higher total n-3 and improved n-3:n-6 ratio obtained in fish, although both VO were not as effective as FO in maintaining EPA and DHA content in Atlantic salmon.

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Endogenous production of n-3 long-chain PUFA from first feeding and the influence of dietary linoleic acid and the α-linolenic:linoleic ratio in Atlantic salmon (Salmo salar)

British Journal Of Nutrition ◽

10.1017/s0007114519001946 ◽

2019 ◽

Vol 122 (10) ◽

pp. 1091-1102 ◽

Cited By ~ 2

Author(s):

Matthew Sprague ◽

Gong Xu ◽

Monica B. Betancor ◽

Rolf E. Olsen ◽

Ole Torrissen ◽

...

Keyword(s):

Linoleic Acid ◽

Atlantic Salmon ◽

Salmo Salar ◽

Chain Pufa ◽

First Feeding ◽

Endogenous Production ◽

Epa And Dha ◽

Salmon Fry ◽

Sunflower Oils ◽

Long Chain

AbstractAtlantic salmon (Salmo salar) possess enzymes required for the endogenous biosynthesis of n-3 long-chain PUFA (LC-PUFA), EPA and DHA, from α-linolenic acid (ALA). Linoleic acid (LA) competes with ALA for LC-PUFA biosynthesis enzymes leading to the production of n-6 LC-PUFA, including arachidonic acid (ARA). We aimed to quantify the endogenous production of EPA and DHA from ALA in salmon fed from first feeding on diets that contain no EPA and DHA and to determine the influence of dietary LA and ALA:LA ratio on LC-PUFA production. Salmon were fed from first feeding for 22 weeks with three diets formulated with linseed and sunflower oils to provide ALA:LA ratios of approximately 3:1, 1:1 and 1:3. Endogenous production of n-3 LC-PUFA was 5·9, 4·4 and 2·8 mg per g fish and that of n-6 LC-PUFA was 0·2, 0·5 and 1·4 mg per g fish in salmon fed diets with ALA:LA ratios of 3:1, 1:1 and 1:3, respectively. The ratio of n-3:n-6 LC-PUFA production decreased from 27·4 to 2·0, and DHA:EPA ratio increased and EPA:ARA and DHA:ARA ratios decreased, as dietary ALA:LA ratio decreased. In conclusion, with a dietary ALA:LA ratio of 1, salmon fry/parr produced about 28 μg n-3 LC-PUFA per g fish per d, with a DHA:EPA ratio of 3·4. Production of n-3 LC-PUFA exceeded that of n-6 LC-PUFA by almost 9-fold. Reducing the dietary ALA:LA ratio reduced n-3 LC-PUFA production and EPA:ARA and DHA:ARA ratios but increased n-6 LC-PUFA production and DHA:EPA ratio.

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