不同碳链长度n-3脂肪酸及脂肪水平对罗非鱼生长、肝功能和餐后血液指标的影响

摘要

An 8-week feeding trial was conducted to evaluate the effects of n-3 fatty acids with different carbon chain lengths and lipid levels on growth, liver function and postprandial blood indices of tilapia ( Oreochromis niloticus) . Four experimental diets were formulated containing either 5% fish oil ( low level of fish oil) , 10%fish oil ( high level of fish oil) , 5% linseed oil ( low level of linseed oil) or 10% linseed oil ( high level of lin-seed oil ) on the basis of practical diet formulation. A total of 360 tilapia with the initial body weight of (43.70±1.06) g were randomly distributed into 4 groups with 3 replicates per group and 30 fish per replicate, and the fish in each group were randomly fed one of four experimental diets. The results showed that no signifi-cant differences were found in finial body weight ( FBW) , specific growth rate ( SGR) , feed conversion ratio (FCR) and protein efficiency ratio (PER) of fish among all groups (P>0.05), but the feed intake (FI) in low level of linseed oil group was significantly lower than that in high level of linseed oil group ( P<0.05) . Se-rum total cholesterol ( TCHO) , high density lipoprotein-cholesterol ( HDL-C) and low density lipoprotein-cho-lesterol ( LDL-C) contents in fish oil groups were higher than those in linseed oil groups; besides, the above indices in high level group were higher than those in low level group of the same lipid source. The peak of ser-um TCHO content in fish oil groups was observed at 6 h after meal, but that in linseed oil groups was observed at 9 h after meal. The bottom of serum HDL-C content appeared at 6 h after meal in 4 groups. Linseed oil groups had higher serum triglyceride ( TG) and very low density lipoprotein-cholesterol ( VLDL-C) contents compared with fish oil groups. With the postprandial time going on, blood glucose content showed a basic de-creasing tendency. The hepatopancreas alanine transaminase ( ALT) activity in fish oil groups was significantly lower than that in linseed oil groups ( P<0.01) , but there were no differences in hepatopancreas aspartate ami-notransferase ( AST) activity among all groups ( P>0.05) . Hepatopancreas malondialdehyde ( MDA) content showed a trend of high level of fish oil group>high level of linseed oil group>low level of fish oil group>low level of linseed oil group, and the difference among all groups was significant (P<0.01). No difference was found in hepatopancreas superoxide dismutase ( SOD ) activity between fish oil and linseed oil groups in the same level (P>0.05), but the hepatopancreas SOD activity in low level of fish oil group was significantly higher than that in high level of fish oil group ( P<0.05) . In conclusion, n-3 fatty acids with different carbon chain lengths and lipid levels have little effects on growth of tilapia, but can affect their liver function and post-prandial blood indices.%在实用饲料配方的基础上分别添加5%鱼油(低水平鱼油)、10%鱼油(高水平鱼油)、5%亚麻籽油(低水平亚麻籽油)和10%亚麻籽油(高水平亚麻籽油),配制4种试验饲料,在室内淡水循环水族缸内饲喂罗非鱼8周,比较研究不同碳链长度n-3脂肪酸及脂肪水平对罗非鱼生长、肝功能以及餐后血液指标的影响。将360尾初重为(43.70±1.06) g的罗非鱼随机分成4组,每组设3个重复,每个重复30尾鱼,每组试验鱼随机饲喂1种试验饲料。结果表明：各组罗非鱼末重、特定生长率、饲料系数、蛋白质效率均无显著差异(P>0.05),但高水平亚麻籽油组的摄食量显著低于低水平亚麻籽油组( P<0.05)。鱼油组罗非鱼血清总胆固醇( TCHO)、高密度脂蛋白胆固醇( HDL-C)以及低密度脂蛋白胆固醇( LDL-C)含量均高于亚麻籽油组,且同一脂肪源的高水平组高于低水平组。鱼油组血清TCHO含量峰值出现在餐后6 h,而亚麻籽油组出现在餐后9 h。各组血清 HDL-C 含量均在餐后6 h 回落到最低值。亚麻籽油组血清甘油三酯( TG)和极低密度脂蛋白胆固醇( VLDL-C)含量高于鱼油组。各组血清TG与VLDL-C含量峰值均出现在餐后6h。随餐后时间的延长,罗非鱼血糖含量基本呈降低趋势。鱼油组肝胰脏谷丙转氨酶(ALT)活性极显著低于亚麻籽油组(P<0.01),而各组间肝胰脏谷草转氨酶(AST)活性差异不显著( P>0.05)。肝胰脏丙二醛( MDA)含量表现为高水平鱼油组>高水平亚麻籽油组>低水平鱼油组>低水平亚麻籽油组,且组间差异极显著( P<0.01)。同一水平下,鱼油组肝胰脏超氧化物歧化酶(SOD)活性与亚麻籽油组没有显著差异(P>0.05),而低水平鱼油组肝胰脏SOD活性显著高于高水平鱼油组( P<0.05)。由此可见,不同碳链长度n-3脂肪酸及脂肪水平不会影响罗非鱼的生长,但会影响其肝功能以及餐后血液指标。