Re-evaluating the dietary requirement of EPA and DHA for Atlantic salmon in freshwater

Dietary intake of linoleic acid (LA) has increased dramatically during the twentieth century and is associated with a greater prevalence of obesity. Vegetable oils are recognised as suitable alternatives to fish oil (FO) in feed for Atlantic salmon (Salmo salarL.) but introduce high amounts of LA in the salmon fillet. The effect on fish consumers of such a replacement remains to be elucidated. Here, we investigate the effect of excessive dietary LA from soyabean oil (SO) on endocannabinoid levels in Atlantic salmon and mice, and study the metabolic effects in mice when SO replaces FO in feed for Atlantic salmon. Atlantic salmon were fed FO and SO for 6 months, and the salmon fillet was used to produce feed for mice. Male C57BL/6J mice were fed diets of 35 % of energy as fat based on FO- and SO-enriched salmon for 16 weeks. We found that replacing FO with SO in feed for Atlantic salmon increased LA, arachidonic acid (AA), decreased EPA and DHA, elevated the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), and increased TAG accumulation in the salmon liver. In mice, the SO salmon diet increased LA and AA and decreased EPA and DHA in the liver and erythrocyte phospholipids, and elevated 2-AG and AEA associated with increased feed efficiency, weight gain and adipose tissue inflammation compared with mice fed the FO salmon diet. In conclusion, excessive dietary LA elevates endocannabinoids in the liver of salmon and mice, and increases weight gain and counteracts the anti-inflammatory properties of EPA and DHA in mice.

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Quantitative Dietary Lysine Requirement of Atlantic Salmon (Salmo salar) Fingerlings

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-037 ◽

1993 ◽

Vol 50 (2) ◽

pp. 316-322 ◽

Cited By ~ 43

Author(s):

J. Stewart Anderson ◽

Santosh P. Lall ◽

Derek M. Anderson ◽

Mary A. McNiven

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Dry Matter ◽

Deficient Diet ◽

Dietary Requirement ◽

Atlantic Salmon Salmo Salar ◽

Lysine Concentration ◽

Gross Energy ◽

Loss Of Appetite ◽

Matter Basis

Triplicate groups of Atlantic salmon (Salmo salar) fingerlings, initial mean weight 4.7 ± 0.2 g, were fed to satiation diets containing 1.24, 1.76, 1.90, 2.19, 2.45, 2.68, and 2.94% lysine and 24.1 MJ of gross energy per kilogram of diet (dry matter basis, DMB) for 70 d. The fish were reared in brackish water (10 ppt) at a temperature of 15 ± 0.9 °C on a 12-h photoperiod. The dietary requirement for lysine, estimated by broken-line regression of growth against dietary lysine level (DMB), was 1.99 ± 0.11%, or 3.98% of the protein when protein was 50.0% of the diet. A dietary lysine requirement of 1.84 ± 0.16% (DMB) was estimated from broken-line regression of expired 14CO2 (following an intraperitoneal injection of L-[U – 14C]lysine) against dietary lysine concentration. Except for loss of appetite, resulting in low food intake and depressed growth, no nutritional deficiency signs were observed in fish fed a lysine-deficient diet for 140 d.

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Requirements ofn-3 very long-chain PUFA in Atlantic salmon (Salmo salarL): effects of different dietary levels of EPA and DHA on fish performance and tissue composition and integrity

British Journal Of Nutrition ◽

10.1017/s0007114516004396 ◽

2017 ◽

Vol 117 (1) ◽

pp. 30-47 ◽

Cited By ~ 46

Author(s):

Marta Bou ◽

Gerd M. Berge ◽

Grete Baeverfjord ◽

Trygve Sigholt ◽

Tone-Kari Østbye ◽

...

Keyword(s):

Atlantic Salmon ◽

Membrane Phospholipids ◽

Commercial Diet ◽

Farmed Salmon ◽

Tissue Integrity ◽

Chain Pufa ◽

Epa And Dha ◽

Dietary Requirements ◽

Low Levels ◽

Better Than

AbstractFarmed salmon feeds have changed from purely marine-based diets with high levels of EPA and DHA in the 1990s to the current 70 % plant-based diets with low levels of these fatty acids (FA). The aim of this study was to establish the impacts of low dietary EPA and DHA levels on performance and tissue integrity of Atlantic salmon (Salmo salar). Atlantic salmon (50 g) in seawater were fed fourteen experimental diets, containing five levels (0, 0·5, 1·0, 1·5 and 2·0 %) of EPA, DHA or a 1:1 EPA+DHA plus control close to a commercial diet, to a final weight of 400 g. Lack of EPA and DHA did not influence mortality, but then-3-deficient group exhibited moderately slower growth than those fed levels above 0·5 %. The heart and brain conserved EPA and DHA levels better than skeletal muscle, liver, skin and intestine. Decreased EPA and DHA favoured deposition of pro-inflammatory 20 : 4n-6 and 20 : 3n-6 FA in membrane phospholipids in all tissues. When DHA was excluded from diets, 18 : 3n-3 and EPA were to a large extent converted to DHA. Liver, skeletal and cardiac muscle morphology was normal in all groups, with the exception of cytoplasm packed with large or foamy vacuoles and sometimes swollen enterocytes of intestine in both deficient and EPA groups. DHA supplementation supported normal intestinal structure, and 2·0 % EPA+DHA alleviated deficiency symptoms. Thus, EPA and DHA dietary requirements cannot be based exclusively on growth; tissue integrity and fish health also need to be considered.

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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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