Growth performance, bioavailability of toxic and essential elements and nutrients, and biofortification of iodine of rainbow trout (Onchorynchus mykiss) fed blends with sugar kelp (Saccharina latissima)

Kit Granby*, Heidi Amlund, Luísa M. P. Valente, Jorge Dias, Grethe Adoff, Vera Sousa, António Marques, Jens Jørgen Sloth, Bodil Katrine Larsen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Aquaculture production is demanding novel feed ingredients that reflect natural marine nutrient levels, that are also essential to humans. In this regard, biofortification through addition of iodine-rich sugar kelp in feed formulations was assessed in a 12 week rainbow trout trial. Yttrium inclusion in feed allowed determinations of apparent absorption coefficients of essential and potentially toxic elements and apparent digestibility coefficient of nutrients. E.g. apparent absorption coefficients in trouts fortified feed with 1–4% dw kelp were 67–61% As, 32–40% Cd, <5% Fe; 80–83% I; 66-58% Se. Iodine concentrations in feed up to 239 mg/kg (∼4% kelp) was proportional to iodine accumulation in trout fillets (R2 = 1.00) with 0.5% transfer ratio. Feed iodine concentrations up to 117 mg/kg (∼2% kelp) did not affect growth performance negatively, but increased significantly protein efficiency ratio after eight weeks feeding. However, 4% kelp meal inclusion affected final growth and hepato somatic index, and caused histomorphological changes in the intestine. All fillets had low toxic element concentrations (As, Cd, Hg, Pb). The potential applicability of Saccharina latissima as feed ingredient to tailor iodine concentration in farmed fish is evident. Consuming of a 160 g fillet (2% kelp) contributes ∼60% of recommended daily iodine intake for adults.
Original languageEnglish
Article number111387
JournalFood and Chemical Toxicology
Volume141
Number of pages12
ISSN0278-6915
DOIs
Publication statusPublished - 2020

Keywords

  • Iodine biofortification
  • Macroalgae
  • Rainbow trout
  • Digestibility
  • Apparent absorption coefficient
  • Arsenic

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