Epsilon Open Archive

Abstract

Salmonids are considered as fatty fish and a healthy food. They are characterized by a high proportion of n-3 long chain polyunsaturated fatty acids (n-3 LCPUFA). There is
great interest in producing high-quality salmonids with a reduced use of fish-based materials and a challenge to adjust feeds towards more sustainable.

This thesis investigated the effects of sesamin, linseed oil (LO), rapeseed oil (RO),krill oil (KO), krill meal(KM), mussel meal (MM), and zygomycete meal (ZM)(Rhizopus oryzae) on fish performance, fatty acid profiles, carotenoids, cytochrome P450 (CYP450) and, colour properties and oxidation in the white muscle of Atlantic salmon (Salmo salar L), rainbow trout (Oncorhynchus mykiss) and Arctic charr (Salvelinus alpinus).

No negative effects on fish performance were found when KM, KO, MM, ZM and sesamin were included in the fish feeds. The FA profile was modified significantly by
these feed compounds. LO and RO increased the α-linolenic acid (ALA) level and decreased the n-3 LCPUFA portion. Sesamin significantly decreased the ALA level and slightly increased the DHA level in some groups of Atlantic salmon and rainbow trout. Stripped-LO showed different effects on the portion of EPA and ALA compared to the LO group. The sesamin content in fish liver was consistent with its level in feeds, while the content in white muscle was similar across all groups. KO, KM and MM contributed a high portion of n-3 LCPUFA and under 3.5 mg/kg astaxanthin to the white muscle of Arctic charr, enhancing a* value. Some groups with a high level of astaxanthin showed high level of oxidation products (thiobarbituric reactive substances). Sesamin and ZM significantly affected the level or activity of CYP 450.

The results of this thesis reveal the different effects of the non-fish-based materials on the fatty acid profile and colour properties in salmonids, suggesting that these feed compounds can be used to improve fish quality with an optimised formula. Results also indicate that new feed raw materials need further evaluation before the full application in commercial fish feeds.