Better fatty acids profile in fillets of Nile Tilapia (Oreochromis niloticus) supplemented with fish oil

Fish oil is used as a supplement in animal feed and is recognized for its positive effects on human health. This work evaluated the fatty acid composition and the nutritional quality of the lipid fraction of Nile tilapia fillets (Oreochromis niloticus) that were supplemented with different levels of fish oil (0% (control group), 5%, 10%, or 15% diet in addition to the ether extract of the commercial formulation) for 30 and 60 days pre-slaughter. The effective treatments were 4.61, 9.22, and 13.83% ether extract based on dry matter, respectively. The influence of hyperlipidic diets on the biometric indexes, the variables of weight and body income analyzed was not verified. The effects of oil level and treatment duration were determined by contrast analysis. Thirty-three fatty acids were identified in fillet, with a predominance of oleic (C18:1n-9), palmitic (C16:0), linoleic (C18:2n-6), and stearic (C18:0) acids. Experimental diets significantly influenced the content of fatty acids, particularly eicosapentaenoic acid (C20:5n-3), docosahexaenoic acid (C22:6n-3) and n-3 docosapentaenoic acid (C22:5n-3). Fish oil supplementation showed lower n-6/n-3 ratios and higher polyunsaturated fatty acids/saturated fatty acids ratios compared with the control, contributing to a reduction in thrombogenic index in the sampled fillets. The experimental diets had no effect on the atherogenic index. Comparison of the duration of treatments (30 days vs. 60 days) demonstrated that the total n-6 fatty acids, n-6/n-3 ratio, and contents of docosapentaenoic acid (C22:5n-6) in fillet decreased with extension of the supplementation time. We conclude that fish oil added to tilapia feed nutritionally enriches the fish fillets and it is a good option for commercial production.