Fish Oil Replacement in Aqua Feeds

Aqua Feeds: Formulation & Beyond Volume 1, Issue 1, 2004
Title:	Fish Oil Replacement in Aqua Feeds
Section:	Feature Articles, pages 3 - 6
Author:	Dr. Sadasivam J. Kaushik Unité Mixte INRA-IFREMER-Univ. Bordeaux I, Station d’Hydrobiolgie INRA, France
E-mail:	kaushik@st-pee.inra.fr

Web Summary

This article provides a succinct overview of the issues and presents the latest advances in fish oil replacement R&D.

It is clear that current levels of fish oil use in aquaculture are not sustainable. While sustainable alternatives to fish oil must be identified, a key consideration will be to ensure that aquaculture products provide the same health benefits offered by products from the natural fisheries. This involves handling issues that require a clear understanding of fatty acid requirements and utilization by aquatic species. Providing an excellent summary of fatty acid requirements of, and utilization by fishes, Dr. Kaushik notes that fish manages to spare HUFA efficiently suggesting that the absolute HUFA utilization necessary for life is relatively low. Based on this, he advocates the use of fish oil only to meet the essential fatty acid requirements of the fish and use of other oils as the major energy source for improved protein efficiency.

Reviewing past work on fish oil replacement, he notes that most studies have shown that it is possible to replace a significant portion of fish oil by vegetable oils such as soybean oil, corn oil, linseed oil, rapeseed oil or palm oil without affecting growth or feed efficiencies. Since the lipid composition of fish depends largely on the dietary fatty acid profile, feeding vegetable oils without the long chain PUFAs such as EPA and DHA will naturally lead to a reduction in the levels of these fatty acids in cultured fish, altering their nutritional value. However, the effects of dietary vegetable oils on flesh fatty acid composition can be reversed by re-feeding fish with diets containing adequate amounts of fish oil. Using this idea, significant breakthroughs have been shown in total replacement of fish oil by plant oils in species such as turbot, brown trout, rainbow trout or Atlantic salmon. Once the fish are grown with vegetable oils over the major part of the life cycle, a finishing diet based on fish oil as the major lipid source can be used to tailor the final flesh fatty acid composition to a desired level for human nutrition and dietetics.

The paper contains 2 figures and one table.

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