在半纯化饲料配方的基础上,分别设计6个α-亚麻酸含量(0.02%、0.55%、1.08%、1.60%、2.13%、2.65%)、6个亚油酸含量(0.86%、1.29%、1.73%、2.16%、2.59%、3.03%),以亚麻籽油、玉米油、棕榈油调节饲料中α-亚麻酸、亚油酸的含量,配制等氮等能(粗蛋白质含量为30.09%,粗脂肪含量为6.87%)的12种半纯化试验饲料,探讨团头鲂幼鱼[初始均重为(59.5±0.5) g]饲料中α-亚麻酸、亚油酸的适宜含量。养殖试验分为α-亚麻酸和亚油酸试验2部分,均设6组,每组4个重复,每个重复20尾,养殖周期为85 d。结果表明:在α-亚麻酸试验中,依据回归方程计算得到,在饲料α-亚麻酸含量分别为1.32%、1.33%时,团头鲂幼鱼具有最大的特定生长率和最小的饲料系数;0.02%组的脏体指数显著低于除1.08%组外的其他各组(P<0.05),肥满度、肝体指数各组间无显著差异(P>0.05);0.02%组血清总胆固醇、甘油三酯含量显著高于0.55%、1.08%组(P<0.05),1.60%组血清高密度脂蛋白含量显著高于0.55%、2.13%组(P<0.05),0.02%组血清低密度脂蛋白含量显著高于其他各组(P<0.05)。在亚油酸试验中,依据回归方程计算得到,在饲料亚油酸含量分别为2.02%、2.03%时,团头鲂幼鱼具有最大的特定生长率和最小的饲料系数;3.03%组的肝体指数显著低于其他各组(P<0.05),肥满度、脏体指数各组间无显著差异(P>0.05);1.29%组血清总胆固醇含量显著高于1.73%组(P<0.05),0.86%组血清甘油三酯含量显著高于1.73%组(P<0.05),1.29%组血清高密度脂蛋白含量显著高于0.86%、3.03%组(P<0.05),各组血清低密度脂蛋白含量无显著差异(P>0.05)。以特定生长率、饲料系数作为主要评价指标,结合部分血清生化指标和形体指标,得到适合团头鲂幼鱼快速生长、维持鱼体正常健康的饲料中适宜的亚麻酸、亚油酸含量分别为1.32%~1.33%、2.02%~2.03%。

This experiment was conducted to estimate the optimal dietary α-linolenic acid (LNA) and linoleic acid (LA ) contents of blunt snout bream (Megalobrama amblycephala) fingerlings [intial average body weight of (59.5±0.5) g]. The flax seed oil, corn oil and palm oil were used as lipid sources to regulate dietary LNA and LA contents, a total of 6 gradients of LNA content such as 0.02%, 0.55%, 1.08%, 1.60%, 2.13% and 2.65%, and 6 gradients of LA content such as 0.86%, 1.29%, 1.73%, 2.16%, 2.59% and 3.03% were designed. Twelve isonitrogenous and isoenergetic semi-purified experimental diets (crude protein content was 30.09%, and lipid content was 6.87%) were formulated. The feeding trial included 2 parts: LNA trial and LA trial. Each trial had 6 groups with 4 replicates per group and 20 fingerlings per replicate. The feeding period lasted for 85 days. The results showed as follows: in LNA trial, according to the regression equations, fish had the biggest special gain rate (SGR) and the smallest feed conversion ratio (FCR) when dietary LNA content was 1.32% and 1.33%, respectively. The viscerosomatic index (VSI) in the 0.02% group was significantly higher than that in the other groups except 10.8% group (P<0.05), while the condition factor (CF) and hepatosomatic index (HSI) were not significantly different among all groups (P>0.05). The serum total cholesterol (TCHO) and triglyceride (TG) contents in the 0.22% group were significantly higher than those in the 0.55% and 1.08% groups (P<0.05); the serum high density lipoprotein (HDL) content in the 1.60% group was significantly higher than that in the 0.55% and 2.13% groups (P<0.05); the serum low density lipoprotein (LDL) content in the 0.02% group was significantly higher than that in the other groups (P<0.05). In LA trial, according to the regression equations, fish had the biggest SGR and the smallest FCR when dietary LA content was 2.02% and 2.03%, respectively. The HSI in the 3.03% group was significantly lower than that in the other groups (P<0.05), while the CF and VSI were not significantly different among all groups (P>0.05). The serum TCHO content in the 1.29% group was significantly higher than that in the 1.73% group (P<0.05); the serum TG content in the 0.86% group was significantly higher than that in the 1.73% group (P<0.05); the serum HDL content in the 1.29% group was significantly higher than that in the 0.86% and 3.03% groups (P<0.05); no significant difference was found in serum LDL content among all groups (P>0.05). In conclusion, SGR and FCR are used as evaluating indicators, and combining with serum biochemical indices and morphological indices, optimal dietary LNA and LA contents of blunt snout bream fingerlings with fast growing and healthy body are 1.32% to 1.33%, and 2.02% to 2.03%, respectively.