EVALUATION OF GENETICALLY ENGINEERED Camelina sativa OIL AS A SOURCE OF DIETARY LIPID FOR RAINBOW TROUT Oncorhynchus mykiss

Farmed fish require a dietary source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), typically supplied by fish oil. With increasing production demands on the aquaculture industry  with the  growing  human  population and  the dependency on wild fish , the continued use of fish oil  is  both environmentally and economically unsustainable. As a sustainable alternative, the oilseed Camelina sativa was genetically engineered (GE) to produce DHA and EPA at levels similar to fish oil.  The present study evaluated the effectiveness of GE Camelina oil as a sustainable source of DHA and EPA in aquafeeds as a dietary lipid replacement.

Three experimental diets were designed : a fish oil control (FO), low (LCO) and high (HCO) levels of GE Camelina oil, and were fed to R ainbow T rout (initial weight 49.8 ± 11 g fish^-1) for 12 weeks. Muscle, liver, brain and eye tissue were sampled for analysis.

After 12 weeks, no significant differences were found in the final weights (178.5-197.8 g fish^-1) and weight gain (119.3-147.9 g fish^-1 ) of fish among treatments. Significant differences were found in feed conversion ratio of fish fed diets containing GE Camelina oil (FO = 1.10 ± 0.08 g fish^-1; LCO = 0.96 ± 0.08 g fish^-1; HCO = 1.38 ± 0.22 g fish^-1 ; p = 0.029).  Significan t differences were noted in the fatty acid profiles of experimental diets and tissues.  In the diet, DHA and EPA content  was  higher in FO and HCO diets than in LCO, while 18:2n-6  (LNA) and 18:3n-3  (ALA)  was higher in LCO and HCO diets than in FO. EPA in m uscle tissue was higher in fish fed HCO and FO diets in comparison to LCO.  DHA stored in muscle tissue was highest in fish fed FO diets.  No significant differences were noted  for  DHA and EPA in brain tissue. Significant differences were noted in orange intensity and firmness (in fillets fed HCO diet in comparison to the FO control, however; other sensory properties of the fillets were not different.  In conclusion, genetically engineered Camelina sativa was found to be an effective substitute for FO as a dietary source of EPA and DHA.