Comparison of effects of vegetable oils blended with southern hemisphere fish oil and decontaminated northern hemisphere fish oil on growth performance, composition and gene expression in Atlantic salmon (Salmo salar L.)

• Published in: Aquaculture
• Main Authors: Pratoomyot, Jarunan, Bendiksen, Eldar Asgard, Bell, J Gordon, Tocher, Douglas R
• Other Authors: University of Stirling, BioMar AS, Institute of Aquaculture, orcid:0000-0002-8603-9410
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2008
• Subjects: Fsh oil; Vegetable oil; Decontamination; Growth performance; Fatty acid composition; Contaminants; Atlantic salmon; Vegetable oils; Fishes Feeding and feeds; Fishes Quality; Fishes Nutrition Requirments; Salmo salar
• Online Access: http://hdl.handle.net/1893/466; https://doi.org/10.1016/j.aquaculture.2008.04.028; http://dspace.stir.ac.uk/bitstream/1893/466/1/Pratoomyot%20et%20al2008.pdf

Replacement of fish oil with sustainable alternatives, such as vegetable oil, in aquaculture diets has to be achieved without compromising the nutritional quality, in terms of n-3 highly unsaturated fatty acid (HUFA) content, of the product. This may be possible if the level of replacement is not too high and oil blends are chosen carefully but, if high levels of fish oil are substituted, a fish oil finishing diet prior to harvest would be required to restore n-3HUFA. However, a decontaminated fish oil would be required to avoid increasing undesirable contaminants. Here we test the hypotheses that blending of rapeseed and soybean oils with southern hemisphere fish oil will have a low impact upon tissue n-3HUFA levels, and that decontamination of fish oil will have no major effect on the nutritional quality of fish oil as a feed ingredient for Atlantic salmon. Salmon (initial weight ~0.8 kg) were fed for 10 weeks with diets in which 60% of fish oil was replaced with blends of soybean, rapeseed and southern hemisphere fish oil (SVO) or 100% decontaminated northern fish oil (DFO) in comparison with a standard northern fish oil diet (FO). Decontamination of the oil was a two-step procedure that included treatment with activated carbon followed by thin film deodorisation. Growth performance and feed efficiency were unaffected by either the SVO or DFO diets despite these having lower gross nutrient and fatty acid digestibilities than the FO diet. There were also no effects on the gross composition of the fish. Liver and, to a lesser extent flesh, lipid levels were lower in fish fed the SVO blends, due to lower proportions of neutral lipids, specifically triacylglycerol. Tissue lipid levels were not affected in fish fed the DFO diet. Reflecting the diet, flesh eicosapentaenoic acid (EPA) and total n-3 fatty acids were higher, and 18:1n-9 lower, in fish fed DFO than FO, whereas there were no differences in liver fatty acid compositions. Flesh EPA levels were only slightly reduced from about 6% to 5% although ...