Effect Of Dietary Vegetable Oils On Growth, Tissue Fatty Acid Composition And Physiological And Biochemical Index Of Genetically Improved Farmed Tilapia Strain Of Nile Tilapia Oreochromis Niloticus

Fish oils are still regarded as good lipid sources of aquafeed formulations, as it provides essential fatty acids such as EPA and DHA, good palatability, high n-3/n-6.However, high dependency on marine fish oil as a major lipid source in aquafeeds has raised major concerns of sustainability for aquaculture in the future due to limited supply of fish oil and expanding global nature of aquaculture production. Continuous increase of world vegetable oil production elevated the interest in inclusion of vegetable oils for aquafeeds to replace and reduce the dependency on fish oil. Tilapia is omnivorous fish which prefer vegetal food. So the vegetable oils maybe good lipid sources for tilapia.The present study aimed to investigate the effect of dietary vegetable oils on growth,tissue fatty acids, serum and liver physiological index and biochemical index of GIFT tilapia. An 8-week growth trial was conducted with GIFT(Genetic Improvement of Farmed Tilapia) tilapia to investigate the supplemented feed diets with different vegetable oil as substitutes for fish oil. Six diets were supplemented with of soybean oil(SO), palm oil(PO), cottonseed oil(CO), rapeseed oil(RO), soybean phospholipid(SL), rapeseed oil(RO), and 1:1:1:1:1soybean oil-palm oil-cottonseed oil-rapeseed oil-phospholipid mixture(MIX), respectively.1. For the tilapia with weight of(12.32±0.02)g reared in recirculation system with fiberglass tanks. Our results showed that: the specific growth rate of RO group was significantly higher than PO, CO, SL and MIX group(P<0.05). The specific growth rate of SO group was significantly higher than CO and PO group(P<0.05). The feed conversion ratio of RO group was significantly lower than PO, CO and SL group(P<0.05), while had no significance with other groups(P>0.05). The fatty acid composition of muscle in fish generally reflected the composition of the diet. The maximum correlation between muscle fatty acid composition and diet fatty acids composition was PO group, and the minimal one was CO group. The activity of serum aspartate transaminase of PO group was significantly higher than RO group(P<0.05).The content of low density lipoprotein cholesterol and the high density lipoprotein cholesterol and of CO group were significantly higher than RO group(P<0.05). The activity of lipoprotein lipase of SO group was significantly higher than CO and RO group(P<0.05). The results suggested that rapeseed oil and soybean oil could be good lipid sources for the diet of the GIFT tilapia.2. For the tilapia with weight of(229.92±0.31)g reared in cages in the pond, our results showed that: the weight gain and special growth ratio of RO group were significantly higher than CO and MIX group(P<0.05). The feed conversion ratio of RO group was significantly lower than MIX group(P<0.05). The fatty acid composition of muscle in fish generally reflected the composition of the diet. The correlation of liver fatty acids composition and diet fatty acids composition was smaller. The activity of serum alkaline phosphatase of RO group was significantly higher than PO and CO group(P<0.05). The activity of lysozyme of RO group was significantly lower than PO and CO group(P<0.05). There were no significant differences on the activities of serum superoxide dismutase, serum lipids and hepatic lipid metabolism(P>0.05). The results suggested that soybean oil, palm oil, rapeseed oil and phospholipid could be regarded as good lipid sources for the diet of the GIFT tilapia.