细鳞鲑幼鱼对饲料中维生素E的需求量

摘要

This study was conducted to investigate the effects of dietary different levels of vitamin E on growth performance, serum biochemical indicators and vitamin E accumulation in body, and to determine the vitamin E requirements of manchurian trout ( Brachymystax lenok) . A total of 600 juvenile manchurian trout with an in-itial body weight of (40.2±3.6) g were randomly divided into 6 groups with 3 replicates per group and 15 fish per replicate. The fish were fed six isonitrogenous and isoenergetic diets containing different levels ( measured values were 16.6, 64.9, 165.5, 316.2, 615.5 and 1214.7 mg/kg, respectively) of vitamin E. The experi-ment lasted for 120 days. The results showed as follows:1) the final weight ( FW) , weight gain rate ( WGR) and special growth rate ( SGR) of manchurian trout were firstly increased and then decreased with dietary vita-min E level increasing. The FW of manchurian trout in 165.5 mg/kg group was significantly higher than that in other groups (P<0.05). The WGR and SGR of manchurian trout in 165.5 mg/kg group were significantly higher than those in 16.6 and 1214.7 mg/kg groups ( P<0.05) . There were no significant differences in feed intake rate, feed conversion rate and protein efficiency rate of manchurian trout among all groups (P>0.05). 2) With the dietary vitamin E level increasing, the serum triglyceride ( TG) and total cholesterol ( TC) con-tents were gradually decreased, which in 615.5 and 1214.5 mg/kg groups were significantly lower than those in the other groups ( P<0.05) . With the dietary vitamin E level increasing, the serum high density lipoprotein cholesterol (HDL-C) content firstly increased and then decreased, which in 165.5 mg/kg group was signifi-cantly higher than that in other groups ( P<0.05) , while which in 64.9 and 615.5 mg/kg groups was signifi-cantly higher than that in 16.6, 615.5 and 1214.5 mg/kg groups ( P<0.05) . The serum low density lipopro-tein cholesterol ( LDL-C ) content had the opposite trend with HDL-C content, which in 165. 5 and 316.2 mg/kg groups was significantly lower than that in other groups (P<0.05). There were no significant differences in the activities of alanine aminotransferase ( ALT) and aspartate aminotransferase ( AST) in serum among all groups ( P>0.05) . 3) With the dietary vitamin E level increasing, the liver vitamin E accumulation was significantly increased ( P<0.05) except that in 15.5 and 1214.5 mg/kg groups ( P>0.05) . The muscle vitamin E accumulation was increased with the dietary vitamin E level increasing, which constant on a level when dietary vitamin E level exceeded 165.5 mg/kg, and the muscle vitamin E accumulation in 165.5, 316.2, 615.5 and 1214.5 mg/kg groups was significantly higher than that in 16.6 and 64.9 mg/kg groups ( P<0.05) . Therefore, dietary appropriate vitamin E supplemental level can improve the growth performance and serum bi-ochemical indicators of manchurian trout, and increase the accumulation of vitamin E in liver and muscle. Ac-cording to the broken-line models, WGR and muscle vitamin E accumulation are used as evaluation indexes, the requirement of vitamin E is 145.87 and 180.98 mg/kg, respectively.%本试验旨在研究饲料中不同水平的维生素E对细鳞鲑幼鱼生长性能、血清生化指标和机体维生素E积累量的影响,并确定细鳞鲑幼鱼对饲料中维生素E的需求量.选取初均质量为(40.2±3.6)g的细鳞鲑幼鱼270尾,随机分成6个组,每组3个重复,每个重复15尾.各组分别投喂不同维生素E水平(实测值分别为16.6、64.9、165.5、316.2、615.5和1214.7 mg/kg)的6种等氮等能的试验饲料.试验期120 d.结果表明:1)细鳞鲑的末均质量(FW)、增重率(WGR)和特定生长率(SGR)均随着饲料维生素E水平的升高呈先升高后降低的趋势,165.5 mg/kg组细鳞鲑的FW显著高于其他各组(P<0.05),165.5 mg/kg组细鳞鲑的WGR和SGR显著高于16.6和1214.7 mg/kg组(P<0.05).各组间细鳞鲑的摄食率、饲料系数和蛋白质效率没有显著差异(P>0.05).2)随着饲料维生素E水平的升高,血清甘油三酯(TG)和总胆固醇(TC)含量均呈逐渐降低的趋势,且615.5和1214.5 mg/kg组显著低于其他各组(P<0.05).随着饲料维生素E水平的升高,血清高密度脂蛋白胆固醇(HDL-C)含量呈先升高后降低的趋势,且165.5 mg/kg组显著高于其他各组(P<0.05),64.9和316.2 mg/kg组显著高于16.6、615.5和1214.5 mg/kg组(P<0.05);而血清低密度脂蛋白胆固醇(LDL-C)含量与HDL-C含量呈相反的趋势,且165.5和316.2 mg/kg组显著低于其他各组(P<0.05).各组间血清谷丙转氨酶(ALT)和谷草转氨酶(AST)活性没有显著差异(P>0.05).3)随着饲料维生素E水平的升高,细鳞鲑肝脏维生素E积累量除615.5与1214.5 mg/kg组间无显著差异(P>0.05)外,呈显著升高的趋势(P<0.05);肌肉维生素E积累量也呈升高的趋势,在饲料维生素E水平大于165.5 mg/kg时恒定在一个水平,且165.5、316.2、615.5和1214.5 mg/kg组肌肉维生素E沉积量显著高于16.6和64.9 mg/kg组(P<0.05).由此可见,饲料中添加适宜水平的维生素E可以改善细鳞鲑的生长性能和血清生化指标,增加肝脏和肌肉维生素E积累量.以增重率和肌肉维生素E积累量为评价指标,根据折线模型得出,细鳞鲑对饲料中维生素E的需求量分别为145.87和180.98 mg/kg.