Abstract
Aquaculture, the fastest growing food production sector cannot continue to rely on finite stocks of marine fish as the primary source of the omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic acid (EPA; 20:5n3) and docosahexaenoic acid (DHA; 22:6n-3), for feeds. A four-month feeding trial was conducted to investigate the impact of a de novo oil, with high levels of EPA and DHA, obtained from transgenic Camelina sativa on growth performance, tissue fatty acid profiles, and expression of lipid metabolism genes when used as a replacement for fish oil in feed for European seabass (Dicentrachus labrax). Triplicate groups of 50 juvenile fish (initial weight 16.7 ± 0.92 g) per tank were fed for 4 months with one of three isolipidic and isoproteic experimental diets consisting of a standard diet containing a commercial blend of fish oil and rapeseed oil (CFO), a diet containing transgenic Camelina oil (TCO), or a blend of fish oil and rapeseed oil with enhanced levels of EPA and DHA (EFO) formulated to match the n-3 LC-PUFA profile of the TCO feed. Final weight of fish fed the GM-derived oil was not different to fish fed either CFO or EFO. Slight lower growth performance of fish fed TCO at the beginning of the trial was related to transient reduced feed intake, possibly caused by glucosinolates in the raw Camelina sativa oil. The GM-derived oil improved the nutritional quality of the fish fillet by enhancing total n-3 PUFA levels compared to the fish fed the other two feeds, and maintained flesh EPA and DHA at the same levels as in fish fed the diets containing fish oil. The metabolic response in liver and intestine was generally relatively mild although diets TCO and EFO seemed to trigger a metabolic response consisting of an up-regulation of both β-oxidation (cpt1a) and fatty acid transport (fabp1), possibly reflecting higher levels of LC-PUFA. Overall, the present study indicated that an oil of terrestrial origin, Camelina sativa, when engineered to contain high levels of EPA and DHA can replace fish oil in feeds for European seabass with no detrimental impact on growth or feed efficiency, while also maintaining or increasing tissue n-3 LC-PUFA contents.
Highlights
Fish are the primary dietary source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) for humans, where eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3) in particular have been recognized to provide health benefits (Calder, 2018; Shahidi and Ambigaipalan, 2018; Innes and Calder, 2020)
The present study aimed to evaluate the effectiveness of oil from GM Camelina sativa as a dietary source of EPA and DHA in feeds for European seabass (Dicentrarchus labrax), a non-oily marine teleost species with limited LC-PUFA biosynthesis capacity
Diets were manufactured at the BioMar Tech Centre (Brande, Denmark) by vacuum coating identical dry basal extruded pellets with either fish oil (FO) and rapeseed oil in a commercial-like blend (CFO), transgenic Camelina oil (TCO; EPA 8.2%, docosapentaenoic acid (DPA) 5.7%, DHA 7.4% of total fatty acids), or an enhanced FO and rapeseed oil blend (EFO) to provide similar EPA and DHA levels to the TCO diet (Table 1)
Summary
Fish are the primary dietary source of n-3 LC-PUFA for humans, where eicosapentaenoate (EPA; 20:5n-3) and docosahexaenoate (DHA; 22:6n-3) in particular have been recognized to provide health benefits (Calder, 2018; Shahidi and Ambigaipalan, 2018; Innes and Calder, 2020). The primary producers of n-3 LC-PUFA are microalgae that are able to directly synthesize EPA and DHA, which are accumulated up the marine food chain to fish through the consumption of phytoplankton and zooplankton (Harris, 2010). For this reason, fish and seafood are the primary sources of n-3 LC-PUFA in the human diet (GOED, 2020). A daily dose of 500 mg of EPA + DHA is recommended for optimal health in humans, which requires consuming at least two portions of fish per week (GOED, 2020)
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