Oils Derived from GM Crops as Sustainable Solutions to the Supply of Long-Chain Omega-3 for On-Growing Atlantic Bluefin Tuna (Thunnus thynnus L.)

Recently Camelina sativa, has been genetically modified to produce oils rich in omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), EPA (eicosapentaenoic acid) and EPA + DHA (docosahexaenoic acid). The aim of this study was to test the feasibility of using these novel sources of de novo EPA and EPA + DHA as substitutes for marine oil in feeds for juvenile Atlantic Bluefin tuna (ABT). The results showed the oils were practical sources of n-3 LC-PUFA which could potentially replace fish oil (FO) in feeds for ABT juveniles. Fish fed the test diets (ECO, EPA alone and DCO, EPA + DHA) displayed good growth performance, survival and feed utilisation approaching that of ABT fed the reference diet (MGK) containing marine fish oil with the rank order being MGK > DCO > ECO. The test diets showed positive effects, upregulating the expression of genes of major nuclear receptors and those of lipid metabolism including digestion, LC-PUFA synthesis and antioxidant pathways. The results indicated that the DCO feed containing both DHA and EPA performed better than the ECO feed with much lower DHA. However, feeds formulated with both these oils may still require supplementary DHA to satisfy the high requirement of ABT for this essential nutrient.