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

Abstract

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.