Fish oil-free diets for Pacific white shrimp Litopenaeus vannamei: The effects of DHA-EPA supplementation on juvenile growth performance and muscle fatty acid profile

Abstract

The influence of a combination of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in fish oil free diets were evaluated on the overall performance of Litopenaeus vannamei. Within this purpose, four isoproteic (approximately 410 g kg−1 of crude protein) and isolipidic diets were manufactured to contain 85 g kg−1 of lipids provide from beef tallow, soybean oil, and the fat contained in the ingredients, supplemented at four levels of DHA-Nature™; 0, 1, 1.7, and 2.4 g kg−1 (containing 240 and 70 g kg−1 DHA and EPA), corresponding to: Control; low, L-DHA; medium, M-DHA; and high, H-DHA. The diets resulted with the final DHA concentration of 10.7 (Control); 13.1 (L-DHA); 17.0 (M-DHA); and 23.7 mg g−1 lipid (H-DHA). Twenty-five L. vannamei juveniles (8.63 ± 0.08 g) were randomly divided into 12 tanks (500-L; in triplicate) fed to satiation four times a day, approximately to a 6% of the total biomass. After seven weeks of experimentation, it was revealed that H-DHA treatment, significantly favored the growth performance compared to the Control. In general, the muscle fatty acids (FA) reflects the diet composition, with significantly higher DHA deposition, in animals fed the H-DHA diet (23.7 mg g−1 lipids of DHA), in comparison with L-DHA and M-DHA diets (13.1 and 17.0 mg g−1 lipids, respectively). The results pointed out preferential oxidation of L. vannamei by FA included in high concentrations in the experimental diets such as 18:1n-9 and 18:2n-6, those of most representative FA in beef tallow and soybean oil composition, respectively. Inversely, it was observed an accumulation of essential long-chain polyunsaturated fatty acids (LC-PUFA), especially EPA and DHA even at low levels of FA inclusion.