| This study was based on GIFT tilapia (Oreochromis niloticus). Effects of different dietary vitamin E level in two lipid level (6%and13%) diets on growth, body composition, body vitamin E concentration and serum biochemical indicators of juvenile and adult GIFT tilapia were conducted. And the effects of dietary choline on growth, body composition, body choline concentration and serum and liver biochemical indicators of juvenile and adult GIFT tilapia were conducted. Based on this data, the optimum dietary vitamin E requirement, the relationship between dietary vitamin E and lipid level, and the optimum dietary choline requirement were estimated. The main results were showed as below.1. The dietary vitamin E requirement of adult GIFT tilapia(Oreochromis niloticus) at two lipid levelsA10-wk growth experiment was conducted to determine vitamin E requirement for adult GIFT tilapia. There were720GIFT tilapia (initial body weight220.31±9.65g), and divided into12groups randomly, every group has three replicates,20fish per replicate. The fish was stocked in36pond cages (1m×1m×1.5m), a cage was a replicate. The experiment diets were formulated, containing two lipid levels, each with six vitamin E levels,5.71(control group),19.29,44.64,70.36,126.07and248.93mg/kg in lipid level of6%,9.64(control group),27.50,52.86,71.07,139.29,257.14mg/kg in lipid level of13%. The effects of dietary vitamin E at two lipid level on growth, body composition, body vitamin E concentration and serum biochemical indicators of adult GIFT tilapia were estimated. After10weeks growth, the results showed that vitamin E can significantly increased the weight gain rate, specific growth rate and feed efficiency (P<0.05). And with the increasing of dietary vitamin E, vitamin E concentration in the liver and muscle were significantly increased (P<0.05). AST and ALT were markedly reduced with increasing dietary vitamin E level. The results reveal that dietary vitamin E can improve the growth performance, efficiency of feed utilization and body antioxidant properties of adult GIFT tilapia; and with the increasing of dietary lipid level would result in the increasing of GIFT tilapia vitamin E requirement. Based on the weight gain rate and feed efficiency:at the lipid level of6%, the dietary vitamin E requirement for GIFTS were36.96～43.12mg/kg; and46.78～54.06mg/kg at lipid level of13%.2. The dietary vitamin E requirement of large fingerlings GIFT tilapia at two lipid levelsA12-wk growth experiment was conducted to determine vitamin E requirement for large fingerlings GIFT tilapia. There were1080GIFT tilapia (initial body weight80.42±5.43g), and divided into12groups randomly, every group has three replicates,30fish per replicate. The fish was stocked in36concrete ponds (r=1.5m, h=0.8m), a pond was a replicate. The experiment diets were formulated, containing two lipid levels, each with six vitamin E levels,6.37(control group),27.55,44.89,62.28,129.92and251.14mg/kg in lipid level of6%,8.87(control group),24.41,47.53,68.82,132.76and266.04mg/kg in lipid level of13%. The effects of dietary vitamin E at two lipid level on growth, body composition, body vitamin E concentration and serum biochemical indicators of juvenile GIFT tilapia were estimated. After12weeks, the results showed that vitamin E can significantly increased the weight gain rate, specific growth rate and feed efficiency (P<0.05); and these indicators would reach stable point earlier at more low dietary lipid level. With the increasing of dietary vitamin E at two lipid levels, the concentration of vitamin E in liver was increased significantly (P<0.05), the activities of SOD and CAT in serum were increased dramatically (P<0.05), and the content of MDA was decreased markedly (P<0.05). The results reveal that dietary vitamin E can improve the growth performance, efficiency of feed utilization and body antioxidant properties of juvenile GIFT tilapia; and with the increasing of dietary lipid level would result in the increasing of GIFT tilapia vitamin E requirement. Based on the weight gain rate and feed efficiency: at the lipid level of6%, the dietary vitamin E requirement for GIFTS were45.11-47.50mg/kg; and71.41～72.73mg/kg at lipid level of13%.3. The dietary choline requirement of adult GIFT ti\apia(Oreochromis niloticus)A10-wk feeding trial was conducted to study the effect of dietary choline chloride supplementation on growth performance, lipid metabolism, feed utilization, body composition, serum biochemical indexes, lipid content in liver and musle and liver choline content of adult GIFT tilapia(Oreochromis niloticus). The basal diet contained27.60%crude protein and6.45%crude lipid. Choline chloride of graded levels (0,300,600,1200,1800and2400mg choline kg-1diet) was supplemented to basal diet to formulate six semi-purified diets containing choline of97.80(control group),375.04,565.74,974.27,1409.81and1824.35mg choline kg-1diet, respectively. Each diet was randomly fed to triplicate of GIFT tilapia with initial average weight of (220.00±8.34) g in18pond cages (1.0m×1.0m×1.5m). The results showed that compared with the control group, the addition of choline in diet significantly improved weight gain rate, specific growth rate and feed utilization(P<0.05). The liver fat content significantly reduced(P<0.05) in the groups fed on diets with choline chloride. The liver choline content and muscle fat content of the groups fed on diets with choline chloride markedly increased (P<0.05). With increasing dietary choline levels, serum triglyceride and cholesterol content increased, the groups with choline chloride significantly higher than the control group(P<0.05), the content of triglyceride and cholesterol content in liver abruptly decreased(P<0.05). Serum aspartate aminotransferase (ALT), alanine aminotransferase (AST) and alkaline phosphatase (ALP) were dramatically reduced (P<0.05) with increasing dietary choline content. It suggested that the supplement of choline chloride could improve tilapia growth performance, feed efficiency, reduce the liver fat content and promote lipid degradation. The proper requirement of choline of the adult GIFT tilapia was506.43mg choline kg-1diet based on the specific growth rate but concentration. |
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