Targeted dietary micronutrient fortification modulates n−3 LC-PUFA pathway activity in rainbow trout (Oncorhynchus mykiss)

• Published in: Aquaculture 2013-11, Vol.412-413, p.215-222
• Main Authors: Lewis, Michael J., Hamid, Noor Khalidah Abdul, Alhazzaa, Ramez, Hermon, Karen, Donald, John A., Sinclair, Andrew J., Turchini, Giovanni M.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; Aquaculture; Autoecology; Biological and medical sciences; Biosynthesis; Coenzymes; Cofactors; Diet; Fatty acid; Fish oil replacement; Fundamental and applied biological sciences. Psychology; General aspects; Minerals; Trout; Vitamins
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2013.07.024

Replacing fish oil (FO) in aquafeeds with sustainable alternatives such as vegetable oils (VO) compromises the content of n−3 long-chain polyunsaturated fatty acid (n−3 LC-PUFA) in the edible portions of farmed fish. Endogenous biosynthesis of n−3 LC-PUFA from C18 precursors is catalysed by several enzymes, which have low activity in carnivorous fish. Rainbow trout were fed on VO-based diets supplemented with increasing levels of selected micronutrients as potential n−3 LC-PUFA biosynthesis co-factors or coenzyme precursors: iron, zinc, magnesium, niacin, riboflavin, pyridoxine and biotin at 100, 200, 300 or 400% of their recommended dietary inclusion. Providing the substrate (ALA, 18:3n−3) and the potential enzyme co-factors was assumed to enhance the efficiency of EPA (20:5n−3) and DHA (22:6n−3) production. Initial evidence was established when DHA and total n−3 LC-PUFA content increased in the whole body of fish from the treatment with the highest micronutrient fortification. Fewer changes were observed in the fillet or liver which was consistent with a marginal regulation of the mRNA expression of key biosynthesis genes in the liver. The potential co-factors seem to stimulate the n−3 LC-PUFA biosynthesis efficiency at the molecular and enzymatic level in rainbow trout fed on ALA-rich diet, leading to metabolic and chemical changes. The interactions between dietary substrate and enzyme co-factors/coenzymes need to be further investigated to advance lipid metabolism research and benefit the aquaculture industry. •Vitamins (B2, B3, B6, B7) and minerals (Fe, Zn, Mg) are involved in LC-PUFA production.•Rainbow trout were fed on vegetable oil with increasing levels of these micronutrients.•DHA and total n−3 LC-PUFA increased in the whole body but not the fillet or liver.•The micronutrients modulated mRNA transcription of key enzymes in the liver.•There is an evidence on enhancing n−3 LC-PUFA production from ALA by micronutrient fortification.