Lund, Ivar and Jokumsen, Alfred (2018) Fatty acid manipulation of rainbow trout fry. [Styring af fedtsyreprofil hos regnbueørred yngel.] .
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Summary
The EU regulation (EC 710/2009) on Organic Aquaculture states that the principles of organic rearing shall include the whole trout production cycle, i.e. the fish production shall be based on organic fry. The Organic Regulation of fish farming states strong limitations on the sourcing of protein and fat ingredients in organic feed, i.e. aiming to phase out fish oil obtained from wild fish stocks and this may lead to a higher inclusion of other oils, especially vegetable oils as these are widely used.
The main difference between vegetable oils (VO) and fish oils (FO) is related to the content of so called long chain essential n-3 (previously denoted Ω-3) and n-6 (previously denoted Ω-6) polyunsaturated fatty acids (LC- PUFAs). These are main constituents of primarily marine oils (i.e. fish oil) but are non-existing in vegetable oils. LC– PUFAs are considered important in early fish larval and fry ontogenesis for optimal physiological development. The dietary content and requirement of specific essential n-3 and n-6 fatty acids is however generally regarded as less important in freshwater fishes than in marine fish species, as some freshwater fishes such as salmonids i.e. rainbow trout to a certain degree are capable to synthesize some of these essential fatty acids for their physiological requirements.
Thus, substitution of marine oils with vegetable oils in feeds for organic aquaculture causes a reduced content of LC- PUFAs. Studies on salmonids (salmon, trout) have examined consequences for growth and physiological influences on juvenile and ongrowing salmonid fish, but little is known regarding short and long term effects on start feeding fry and their immunecompetance and ability to cope with stress and robustness towards inflectional diseases.
Summary translation
Ifølge EU regelsættet for økologisk akvakultur skal den økologiske fiskeproduktion udelukkende være baseret på økologisk yngel. Da medicinbehandling af økologisk ørred er uønsket og kun er tilladt i stærkt begrænset omfang, er ynglens robusthed overfor bl.a. den alvorligste yngelsygdom i dansk ørredopdræt, YDS (”yngeldødeligheds-syndrom”), særdeles vigtig. Ynglens robusthed kan muligvis relateres til ynglens swim-up adfærd (first feeding) og performance under opvæksten. Indholdet af specifikke essentielle Ω-3 fedtsyrer i foderet til ynglen er særlig vigtig for fiskens vækst, sundhed og velfærd, herunder robusthed overfor stress.
Der mangler imidlertid viden om evt. effekt af erstatning af fiskeolie med plantebaserede olier og deraf følgende ændringer i fedtsyre sammensætning og evt. afledede effekter på vækst og overlevelse, samt fysiologiske markører som stress resilience og immunkompetence. Dettegælder i såvel moderfiskefoder som yngelfoderet.
| EPrint Type: | Report |
|---|---|
| Keywords: | Rainbow trout, organic, fatty acids, HUFA, diet |
| Subjects: | Animal husbandry > Feeding and growth Animal husbandry > Health and welfare |
| Research affiliation: | Denmark > Organic RDD 2 > RobustFish |
| Deposited By: | Jokumsen, Senior Advisory Scientist Alfred |
| ID Code: | 33385 |
| Deposited On: | 23 Aug 2018 09:54 |
| Last Modified: | 23 Aug 2018 09:54 |
| Document Language: | English |
| Status: | Unpublished |
| Refereed: | Not peer-reviewed |
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