Researching Alternatives to Fish Oils in Aquaculture
In the RAFOA project, the four main European aquaculture species, Atlantic salmon, rainbow trout, sea bass and sea bream, were grown on diets containing variable amounts of vegetable oils (VO) but with sufficient essential fatty acids (EFA) provided by dietary fishmeal.
The overall objectives were;
- To replace as much as possible of the fish oil used in aquaculture feeds with vegetable oils, without compromising the health, welfare and growth performance of the fish.
- To maintain health benefits, taste and other quality characteristics important to processor and consumers preferences.
- To advance basic scientific knowledge of fish lipid nutrition.
This was achieved by conducting two large scale trials, for each species. In the first trials (RAFOA I), all species were grown from juveniles to market size on diets containing different ratios of FO to VO with the latter being either rapeseed (RO), linseed (LO) or olive oils (OO).
In the second trials (RAFOA II), all species were grown from first feeding, or as close to first feeding as possible, on a high VO replacement diet which was agreed by the project partners after the RAFOA I trials were completed.
Thus, the RAFOA II diets used a blend of VOs that would replicate the FO normally used for the commercial production of that species, in this case capelin oil for the salmonids and anchovy oil for the marine fish. The blend of oils was formulated to replicate the FO in terms of saturated, monounsaturated and polyunsaturated fatty acid concentrations and ratios except there would be none of the HUFA found in FO.
The VO blend, composed of RO, LO and palm oil (PO) was used to replace between 60 and 100% of the added FO in the four species studied. In both trials I & II, following the feeding of various FO/VO ratios, all fish groups were grown for a period, of up to 24 weeks, on a FO finishing diet to follow restoration of n-3 HUFA and wash out of VO fatty acids.