Growth and Fatty Acid Composition of Juvenile Spotted Halibut (Verasper variegatus) Fed Diets with Fish Oil Replaced by SoyBean Oil

Abstract:

An 8-week experiment was conducted to investigate the effects of the replacement of dietary fish oil (FO) with soybean oil (SO) on growth, lipid deposition, and fatty acid composition of juvenile spotted halibut. Four isonitrogenous and isolipidic practical diets were formulated with SO replacing 0, 25%, 50%, and 75% FO, respectively. In total, 360 juvenile spotted halibut, with an initial body weight of (65.47±1.57) g were randomly distributed into four groups; three replicates were used per group and 30 fish were used per replicate. The fish in each group were randomly fed one of the four experimental diets. The following results were obtained: (1) Compared with 100% FO group, the feed conversion rate of spotted halibut was significantly increased (P<0.05), whereas the weight gain rate was significantly decreased (P<0.05). (2) SO replacement levels had no significant effects on body composition and muscle lipid content of juvenile spotted halibut (P>0.05), but had a significant effect on the liver lipid content of juvenile spotted halibut (P<0.05). The liver lipid content in the 50% and 75% SO groups was significantly higher than that in 100% FO group (P<0.05). (3) The fatty acid composition in the muscle was positively correlated with dietary fatty acid composition. Compared with the 100% FO group, the content of linoleic acid (C18:2n-6) and linolenic acid (C18:3n-3) in the muscle were significantly increased (P<0.05), whereas the content of eicosapntemacnioc acid (EPA) and docosahexaenoic acid (DHA) in the muscle were significantly decreased (P<0.05). This study suggested that there were no significant effects on the growth of juvenile spotted halibut when dietary fish oil was replaced by soybean oil. However, the fatty acid composition of muscle was significantly altered.