Rate of change in the fillet fatty acid profile of Nile tilapia to attain a nutraceutical level of DHA + EPA for human consumption

Nile tilapia, Oreochromis niloticus, grows adequately in the absence of dietary omega-3 long-chained polyunsaturated fatty acids, such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid. However, its fatty acid profile can be enriched by feeding finishing diets for some time before harvesting, to reach a desirable content of 250 mg of DHA + EPA in a 100 g fillet, recommended as the daily intake of these essential fatty acids for human consumption by the Food and Agriculture Organization of the United Nations, thus improving its economic and nutritional value as a nutraceutical. The objective of this study was to evaluate the rate of change in the fatty acid profile of tilapia's fillet by feeding diets formulated with soy (SO) or fish oil (FO) in an 8-week bioassay, with two additional treatments, feeding FO for four weeks followed by SO for four additional weeks (FO/SO), or the opposite treatment (SO/FO). No significant differences among treatments were observed at the end of the study for growth performance (weight gain: 103.28–115.83 g; specific growth rate: 6.60–6.83% day⁻¹; daily weight gain: 1.95–2.19 g day⁻¹; survival: 96.67–100%), feed efficiency (1.16–1.31), body indices (hepatosomatic index: 1.48–1.89%; condition factor, K: 2.25–2.43), or proximate composition of the fillet, confirming the versatility of tilapia to efficiently use lipid sources of different nature. However, the fatty acid profile of the dietary lipid source directly influenced the fatty acid profile of the fillet; it was confirmed that, under these experimental conditions, it is possible to enrich the fillet of O. niloticus and reach the concentration of 250 mg of DHA + EPA in a 100 g fillet in just 10 days, for fish of the experimental size (3.11 g of individual initial weight) used in this study and under the prevailing experimental conditions.