The effect of diets including fish oil sources and their use in cycles growth and fatty acid composition of juveniles European seabass (Dicentrarchus labrax)

In this study; the possible effects of alternate feeding schedueles on retention of n-3 longchain fatty acids (mainly EPA and DHA) in sea bass juveniles was evaluated over an 8 weeks period. European seabass (Dicentrarchus labrax,2.4 g) juveniles were fed three type fish oil (FO),blend of three oils (canola, linseed and soybean oils)supplemented with 60% (VO60) and 80% (VO80). Juveniles were fed one of the three experimental diets. Test diets were regularly alternated in a serie of weekly cycles (2VO60: 2 weeks on FO and 2 weeks VO60, 2VO80: 2 weeks on FO and 2 weeks VO80). The highest specific growth rate was found in VO80 in comperation other groups (p<0.05). No significant difference was observed in terme of daily feed intake and feed conversion ratio (p>0.05). The highest protein content was detectedinVO80whereas FOhad the lowest proten content in whole body. Whole body fatty acid profile was modified by associated feding scheduels and was generally reflective of dietary fatty acid profile.The higher levels of linolenic acid (LA,18:2n-6) was found in VO80 in which fish were fed with highest vegetable oil diets. ALA (18:3n-3) was the highest in 2VO60group (p<0.05). A significant increases in ecosapentaenoic acid (EPA,20:5n-3) was observed in in FO and 2VO60 whilesame increasing trend in decosahexaenoic acid (DHA,22:6n-3) was detected in following groups;FO, 2VO60and 2VO80(p<0.05). The highest lipid digestion was observed in alternated groups (2VO60 and 2VO80) (p<0.05). The result of the present studyshowedthat the existence of alternated feeding scheduels in specific fatty acid deposition (EPA and DHA) in European sea bass.