Effect of alternate feeding with fish oil- and peanut oil-based diets on the growth and fatty acid compositions of European seabass fingerlings (Dicentrarchus labrax) in the recirculated systems

The aim of this study was to evaluate the effects of alternate feeding regime with fish oil- and peanut oil-based diets on fatty acid profiles and growth performances of European seabass fingerlings (Dicentrarchus labrax). Six trials were implemented; fish oil trial [C; continuously fed by diet with fish oil (FO)], peanut oil trial [P; continuously fed by diet with peanut oil (PO)], mixture oil trial (PC; continuously fed by diet containing both %50 FO and %50 PO), alternate cycled feeding three trials [(3P/3C; fish fed by diet with PO for 3 weeks and FO for the following 3 weeks), (3PC/3C; fish fed by diet with PC for 3 weeks and FO for following 3 weeks) and (9P/3C; fish fed by diet with P for 9 weeks and C for following 3 weeks)] for 12 weeks. Significantly higher SGR and the best FCR were detected in P and 3PC/3C and 9P/3C groups, respectively, compared with C group (p > 0.05). The lowest HSI and VSI were in the C group (p > 0.05). The highest crude protein was determined in 3P/3C group while protein ratios were higher in cycled fed groups than in the experimental groups (p > 0.05). The highest crude lipid were detected in P group (p > 0.05). The higher SFA level was detected in 9P/3C group (p < 0.05), whereas C group had the lowest content. While P group had the highest fillet MUFA content, which was predominantly made up of OA, the lowest MUFA was determined in the 3PC/3C and C groups. The highest LA was observed in C group (p < 0.05). The ArA was higher in the cycled fed groups than the diet groups. EPA, n-3 PUFA and n3/n6 rates were significantly higher (p < 0.05) in cycled fed groups, compared with the diet groups. The DHA ratio was significantly lower in 9P/3C group compared with the other groups. Also, the lipid quality of the flesh was directly related to the EPA and DHA ratios, and a higher quality product was revealed at the end of cycled feeding with the low IA, IT and high FLQ and h/H values obtained. This study shows that cycled feeding regimes by diets including vegetables oil and FO may be used in European seabass culture.