title: Echium oil is better than rapeseed oil in improving the response of barramundi to a disease challenge.
abstract: Pathogen infection stimulates the fatty acid (FA) metabolism and the production of pro-inflammatory derivatives of FA. Barramundi, Lates calcarifer, was fed on a diet rich in preformed long-chain (⩾C20) polyunsaturated fatty acids (LC-PUFA) from fish oil (FO), to compare with diets containing high levels of C18 precursors for LC-PUFA - stearidonic (SDA) and γ-linolenic acid (GLA) - from Echium plantagineum (EO), or rapeseed oil (RO) rich in α-linolenic acid (ALA), but a poor source of LC-PUFA and their precursors. After 6weeks, when growth rates were similar amongst the dietary treatments, a sub-lethal dose of Streptococcus iniae was administered to half of the fish, while the other half were maintained unchallenged and were pair-fed with the infected fish. Under a disease challenge situation, the tissue FA depots depleted at 3days post-infection (DPI) and were then restored to their previous concentrations at 7DPI. During the infection period, EO fish had a higher content of n3 and n6 PUFA in their tissues, higher n3:n6 PUFA ratio and reduced levels of the eicosanoids, TXB2 and 6-keto-PGF1α, in their plasma compared with RO fish. Fish fed on FO and EO had a longer lasting and enduring response in their FA and eicosanoid concentrations, following a week of bacterial infection, compared with those fed on RO. EO, containing SDA and GLA and with a comparatively higher n3:n6 PUFA ratio, proved more effective than RO in compensating for immunity stress.
authors.affiliation: National Centre for Marine Conservation and Resource Sustainability, University of Tasmania, Launceston, TAS 7250, Australia. ramez.alhazzaa@deakin.edu.au
authors.forename: Ramez
authors.initials: R
authors.lastname: Alhazzaa
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Bridle
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Mori
authors.forename: Anne E
authors.initials: AE
authors.lastname: Barden
authors.forename: Peter D
authors.initials: PD
authors.lastname: Nichols
authors.forename: Chris G
authors.initials: CG
authors.lastname: Carter
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D019587:Dietary Supplements / Q000032:analysis; D036661:Echium / Q000737:chemistry* / Q000378:metabolism; D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D005393:Fish Diseases / Q000378:metabolism* / Q000382:microbiology; D010473:Perciformes / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D010938:Plant Oils / Q000737:chemistry / Q000378:metabolism*; D000074262:Rapeseed Oil; D013290:Streptococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013291:Streptococcus / Q000502:physiology
chemical_list: D005229:Fatty Acids, Monounsaturated; D005231:Fatty Acids, Unsaturated; D010938:Plant Oils; D000074262:Rapeseed Oil