n-3 Polyunsaturated fatty acid-rich vegetable oils and blends

Abstract

Linseed, camelina, perilla and echium oils are n-3 C18 polyunsaturated fatty acid (PUFA)-rich vegetable oil sources viewed as favorable replacements to fish oil in aquaculture feed (aquafeed) production in consideration of their high α-linolenic acid (ALA; 18:3n-3) and/or stearidonic acid (SDA; 18:4n-3) contents and potential for subsequent bio-conversion to n-3 long chain polyunsaturated fatty acids (LC-PUFA) in farmed aquatic species. While the total production of these oils is currently low in comparison with other terrestrial oil sources, their distinct fatty acid composition and high n-3/n-6 ratio delivers a unique substitute to fish oil in aquafeeds, presently unparalleled in other alternative terrestrial oil sources. The dietary inclusion of these oil sources has therefore attracted significant research attention, resulting in a multitude of investigations across a broad range of aquatic species (finfish and crustaceans). Generally, providing that the essential fatty acids (EFA) requirements of the species under investigation were met and an adequate level of fishmeal was present in the diet, it was found possible to replace 100 % and 60 -70 % of the dietary fish oil component for freshwater and marine species, respectively, with minimal impact on growth performance indices. However, the substitution of fish oil with n-3-rich vegetable oils and/or vegetable oil blends resulted in substantially reduced concentrations of health promoting eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) in the edible portion of the farmed species. This Chapter provides an overview of the use of n-3 PUFA-rich vegetable oils and/or vegetable oil blends for use in aquafeeds. In particular, key aspects of oil production, processing and refinement will be presented and individual differences pertaining to the physical, chemical and nutritional characteristics of the oil types will be highlighted. Following on from this, a summary of the key findings relevant to n-3 PUFA-rich vegetable oil inclusion in aquafeeds will be discussed, with particular emphasis placed on growth performance and nutritional modification.