| A feeding trial of three fat (4,8and12%) and three choline levels (500,750and1000mg/Kg) was conducted to determine the optimum level of dietary fat and choline for juvenile tilapia (Oreochromis niloticus) focusing on growth performance, blood biochemical index, serum antioxidant index, fat metabolism enzyme of liver and blood biochemical index under low temperature. Three replicate groups of tilapia (average weight of1.12±0.02g) were fed the experimental diets for9weeks. The experiment were divided into goup1to group9.At the end of the feeding trial:1) Tilapias of group2,3,5,6had a better performance in survival rate, weight gain, special growth rate, relative fatness and feed coefficient.2) Tilapia fed diets of group4,5shown lower cholesterol,low-density lipoprotein cholesterol and sugar level of blood However, the high-density lipoprotein cholesterol level of blood followed the opposite pattern, which was higher.3) Blood albumin of tilapias fed diet of group3,5,6were higher,but which ALT and AST were lower.4) Catalase,total antioxidant and superoxide dismutase in serum of tilapias fed diet of goup2,3,5,6were higher On the other hand, the malondialdehyde in serum fed diet of goup 2,3,5,6were lower.5) Carnitine acyl transferase and total esterase in liver of tilapias fed diet of group5were higher. Tilapia fed diets of group5shown lower fatty acid synthase in liver.6) Tilapia fed diets of group5,6shown higher total protein, albumin, globulin and high-density lipoprotein cholesterol level of blood at low temperature. On the other hand, the glutamyl transpeptidase, creatinine and low-density lipoprotein cholesterol level of blood at low temperature of tilapias fed diets of group5,6were lower.In summary, diets of group5which containing8%fat with750mg/Kg choline shown positive effects on grow performance, immunity, antioxidant capacity and fat metabolism in liver for juvenile tilapia. It can be indicated that the optimum dietary fat and choline is8%and750mg/Kg for juvenile tilapia. |
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