Effects Of Linseed Oil On Growth, Body Composition, Lipid Metabolism And Antioxidant Capacity Of Gift Tilapia(Oreochromis Niloticus) Juvenile

Fish oil is a quality lipid source in aquaculture, but there is in short supply and high price. Currently, looking for other suitable alternative oil source is becoming a hot spot in aquaculture research. Flax is one of the top ten oil-bearing crops in the world, and there is about110,000tons of linseed oil in China yearly. Nowadays, linseed oil is widely noted by aquatic animal nutritionists because of they is rich in linolenic acid. Some studies have shown that it is feasible to use linseed oil in aquatic feed. However, there is little information about how linseed oil affect the growth and fatty acid composition of fish. In order to determine the effects of linseed oil on growth, body composition, lipid metabolism and antioxidant capacity of gift tilapia juvenile. There are two experiments were performed in our study. The first is constitute with different level of linseed oil as the single lipid. The second is based on linseed oil to compound different n-3/n-6level. Through the present study, we hope to find a suitable linseed oil proportion of tilapia feed, view to provide a theoretical basis for the scientific use of linseed oil in aquatic feed.1. Effects of different linseed oil level on growth, body composition, lipid metabolism and antioxidant capacity of gift tilapia(Oreochromis Niloticus) juvenile.The present study was conducted to evaluate the effects of different linseed oil (LO) level on growth performance, body composition, lipid metabolism and antioxidant capacity of tilapia. Four practical diets were formulated to contain4levels of LO (0%,1.5%,3%and4.5%) on an equal nitrogen basis (CP=33%). Tilapia{Oreochromis Niloticus, initial weight9.15±1.53g) were fed in a recirculating freshwater system for8weeks. The present results showed that, with the dietary LO level increasing, the specific growth rate (SGR) and final body weight (FBW) were significant increased (P<0.05), feed conversion ratio (FCR) was significant lowered(P<0.05), they all remain stable after3%. With the dietary LO level increasing, crude lipid of whole fish was significant increased, but the crude protein was significant decreased (P<0.05); eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) in muscle were significant increased,18:3n-3, DHA and EPA in hepatopancreas were significant increased (P<0.05), but they don’t continue to increase after3%(P>0.05); cholesterol (CHOL), triglyceride (TG), low density lipoprotein cholesterol (LDL-G), very low density lipoprotein cholesterol (VLDL-G), high density lipoprotein cholesterol (HDL-G) in serum and malic dehydrogenase (MDH), malonaldehyde (MDA) in hepatopancreas were significant increased (P<0.05); the activities of lipoprotein lipase (LPL), superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas were significant increased (P<0.05), but they were significant decreased after3%. These results suggested that supplementation with3%LO showed best growth, n-3polyunsaturated fatty acid (n-3PUFA) and immune response of tilapia.2. Effects of different n-3/n-6level on growth, body composition, lipid metabolism and antioxidant capacity of gift tilapia (Oreochromis Niloticus) juvenile.The present study was conducted to evaluate the effects of different n-3/n-6level on growth performance, body composition, lipid metabolism and antioxidant capacity of tilapia. A basal diet was supplementation with soybean oil (SO), LO and fish oil (FO). Four practical diets were formulated to contain4levels of n-3/n-6(0.3,0.4,0.5,0.6) on isonitrogenous (CP=33%) and isoenergetic (EE=5%). Tilapia(Oreochromis Niloticus, initial weight5.32±1.01g) were fed in a recirculating freshwater system for8weeks. The present results showed that, with the dietary n-3/n-6increasing, SGR and FBW were significant increased(P<0.05), but the FCR was significant decreased(P<0.05). There were no significant differences on whole body composition (P>0.05). With the dietary n-3/n-6increasing, DPA, DHA, n-3PUFA in muscle and18:3n-3, DPA in hepatopancreas were significant increased (P<0.05);18:3n-6, ARA in muscle and18:2n-6, ARA,22:4n-6in hepatopancreas were significant decreased (P<0.05); MDA in hepatopancreas was significant decreased (P<0.05). Fish fed diet with0.5showed higher activities of MDH, LPL, SOD and CAT in hepatopancreas, higher contents of CHOL, TG, LDL-G and VLDL-G in serum and lower contents of HDL-G in serum (P<0.05). These results suggested that fish fed diet with0.5showed best growth, n-3PUFA and immune response of tilapia.