title: Requirements of n-3 very long-chain PUFA in Atlantic salmon (Salmo salar L): effects of different dietary levels of EPA and DHA on fish performance and tissue composition and integrity.
abstract: Farmed 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 the n-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.
authors.affiliation: 1Nofima (Norwegian Institute of Food, Fisheries, and Aquaculture Research),PO Box 210,N-1432 Ås,Norway.
authors.forename: Marta
authors.initials: M
authors.lastname: Bou
authors.affiliation: 3Nofima,N-6600 Sunndalsøra,Norway.
authors.forename: Gerd M
authors.initials: GM
authors.lastname: Berge
authors.affiliation: 3Nofima,N-6600 Sunndalsøra,Norway.
authors.forename: Grete
authors.initials: G
authors.lastname: Baeverfjord
authors.affiliation: 4BioMar AS,N-7484 Trondheim,Norway.
authors.forename: Trygve
authors.initials: T
authors.lastname: Sigholt
authors.affiliation: 1Nofima (Norwegian Institute of Food, Fisheries, and Aquaculture Research),PO Box 210,N-1432 Ås,Norway.
authors.forename: Tone-Kari
authors.initials: TK
authors.lastname: Østbye
authors.affiliation: 5Nofima,Kjerreidviken 16,N-5141 Fyllingsdalen,Norway.
authors.forename: Odd Helge
authors.initials: OH
authors.lastname: Romarheim
authors.affiliation: 3Nofima,N-6600 Sunndalsøra,Norway.
authors.forename: Bjarne
authors.initials: B
authors.lastname: Hatlen
authors.affiliation: 1Nofima (Norwegian Institute of Food, Fisheries, and Aquaculture Research),PO Box 210,N-1432 Ås,Norway.
authors.forename: Robin
authors.initials: R
authors.lastname: Leeuwis
authors.affiliation: 6AVS Chile S.A.,Imperial 0655-4A,Puerto Varas,Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Venegas
authors.affiliation: 1Nofima (Norwegian Institute of Food, Fisheries, and Aquaculture Research),PO Box 210,N-1432 Ås,Norway.
authors.forename: Bente
authors.initials: B
authors.lastname: Ruyter
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary*; D004281:Docosahexaenoic Acids / Q000008:administration & dosage* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage* / Q000378:metabolism; D006321:Heart / Q000033:anatomy & histology / Q000187:drug effects; D007422:Intestines / Q000033:anatomy & histology / Q000187:drug effects; D008099:Liver / Q000033:anatomy & histology / Q000187:drug effects; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000187:drug effects*; D009751:Nutritional Requirements; D020317:Salmo salar / Q000502:physiology*
chemical_list: D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid
keywords:  
                    n-3 VLC-PUFA 
                    n-3 very-long-chain PUFA;  DPA docosapentaenoic acid;  EFA essential fatty acid;  FA fatty acid;  NL neutral lipids; Aquafeed; DHA; EPA; Essential fatty acids; Fat; Phospholipids