Growth performance, swimming capacity, and fillet quality in rainbow trout fed a transgene-derived omega-3 and carotenoid-enriched oil

Abstract

A new oil from transgenic Camelina sativa was evaluated for its potential to serve as a primary source for eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and astaxanthin in feed for rainbow trout (Oncorhynchus mykiss). Experimental diets were formulated containing either the transgene-derived oil (CAM) or a blend of fish and vegetable oils (CTL). The two diets were given to quadruplicate tanks of 30 fish (body weight 294 ± 32 g) for 10 weeks. Some of the fish were exercised in a swim tunnel prior to sampling. At sampling, muscle tissue was collected for fillet quality assessment and plasma to measure oxidative stress markers. Dietary treatment had no significant impact on final body weight. The fatty acid profile of rainbow trout fillets reflected that of the experimental diets with higher levels of linoleic acid, arachidonic acid, EPA and DHA in fish fed CAM. Levels of corresponding lipid inflammatory mediators, except for those derived from DHA, were pre-exercise elevated in plasma of fish fed CAM. Similarly, dietary ketocarotenoid levels were reflected in the fillet of fish with lower astaxanthin in fish fed CAM compared to CTL, which agreed with differences in fillet color. Dietary treatment had no significant impact on swimming performance. Plasma cortisol and 8-isoprostane were elevated post-exercise, irrespective of dietary treatment. Feeding the transgene-derived oil supported normal growth and increased fillet EPA and DHA levels above standard. A comparable swimming capacity and stress response suggests that the inclusion of the transgenic camelina oil did not impair fish welfare.