Effect of alternate phases of canola oil and fish oil level on the growth performance and fatty acid profiles of juvenile European seabass (Dicentrarchus labrax L. 1758)

Seven groups of European seabass (Dicentrarchus labrax L.) were fed three type diets in which the added oil was 100% fish oil (FO),100% canola oil (CO), 50%FO+50%CO with fish oil and canola oil based diet were regularly alternated in a series of weekly cycles(1W:alternation of 1 weeks on CO and 1 weeks FO,1W:alternation of 1 week 50%FO+50%COand 1 week 100%FO,3W: alternation of 3 weeks FO and 3 weeks CO), over a 12 week period. The use of canola oils in European sea bass diets did not affect fish survival. Specific growth rate (SGR) for all periods was similar in all experimental groups. No significant differences were found in daily feed intake. Whole body composition did not show any differences among dietary treatment in protein, dry matter and ash content. Lipid levels of whole body were lower in fish fed FO, CO, 1week 50%CO/FO+100%FO compared with fish fed 50%FO+50%CO. LA(18:2n-6) levels did not show any differences among dietary treatment. On the other hand LNA is highest in CO diet. Total monounsaturated fatty acid was highest in CO diet. Whole body percentages of EPA (20:5n-3) were highest in 100%FO, 1week 50%FO+50%CO and 1 week 100%FO, 3 week 50%FO+50%CO and 3 week 100%FO and whole body percentages of DHA (22:6n-3) were highest in 100%FO, 1week 50%FO+50%CO and 1 week 100%FO, 3 week 50%FO+50%CO and 3 week 100%FO group. As a result of the this study; the great ability for bioconversion of n-3 FA, canola oil is a promising alternative to fish oil in formulating feed and alternate weekly cycles for European sea bass.