Lipid nutrition in Arctic charr, Salvelinus alpinus (L.): a mini review

Abstract. Several investigations have used Cr₂O₃ (chromic oxide) as an indigestible marker in digestibility studies. However, in this review the effect of chromic oxide on dietary lipid during passage through the digestive tract, and the gastrointestinal microflora in long-term nutrition studies in Arctic charr, Salvelinus alpinus (L.), are discussed. Based on these results it is suggested that the use of chromic oxide may lead to erroneous results. Furthermore, this paper focuses on the effect of dietary linoleic add (18:2 n–6), acetate and salinity on lipid and individual fatty acid digestibilities in Arctic charr.
No full studies have been carried out regarding the essential fatty acid requirement (EFA) of Arctic charr. Available data indicate that (n–3) polyunsaturated fatty acids (PUFAs) are the prime EFA, as in most other salmonids. Furthermore, quantitative EFAn requirements may be higher than the 1% dietary level described for other salmonids. Feeding (n–3) PUFAs at 1% lead to high contents of (n–9) PUFAs in the polar lipids, presently recognized as'indicators'of EFA deficiency. Moreover, this review focuses on elongation and desaturation of short-chain EFA to their C₂₀ C ₂₂ counterparts, and the feedback inhibition of this ability.