Effects of dietary lipids on growth and fatty acid composition in Russian sturgeon (Acipenser gueldenstaedtii) juveniles

Juvenile Russian sturgeon (Acipenser gueldenstaedtii) fed feeds including fish oil, soybean oil and sunflower oil were researched and the effects of the feeds on the growth performance and fatty acid composition of the fish were studied. In the Sapanca Inland Waters Research and Experiment Department of istanbul University's Faculty of Fisheries, sturgeon juveniles having an approximate initial weight of 27.23 +/- 0.98 g were fed experimental feeds containing different kinds of oil for 63 days. Weight gain was 36.83 +/- 1.84 g in the fish oil group, 37.63 +/- 1.76 g in the sunflower oil group and 32.91 +/- 1.93 g in the soybean oil group. Feed conversion ratios were 1.30, 1.30 and 1.45, respectively. The experimental feeds contained 43.79% crude protein and 13.98% crude lipid. At the end of the feeding trials, whole body fat was found 4.65% in the fish oil group, 5.19% in the sunflower oil group and 4.73% in the soybean oil group. Growth performance parameters (HSI, VSI, FCR and SGR) varied significantly among the groups (P <= 0.05). The fatty acid composition analyses showed that total n-3 and n-6 in the whole body fatty acids and the liver fatty acid contents of fish fed feeds contain different kinds of oil were significantly different (P ! 0.05). Naturally, in the groups fed vegetable oil, the ratio of total n-6 fatty acids was higher (22.58 and 22.98) than that in the fish oil group (11.39), and in the group fed fish oil, the n-3 fatty acid ratio was higher (21.57) than that in the vegetable oil groups (13.15 and 15.00). Similar results were found for the values of liver fatty acid composition. These results suggest that sturgeon require both n-3 and n-6 fatty acids and accumulation of these fatty acids in the flesh and liver was affected by fatty acids in the feeds. Therefore, it is possible to use a certain amount of soybean oil or sunflower oil instead of fish oil in sturgeon diets.