本试验旨在研究饲料中不同亚麻酸(C18∶3n-3)/亚油酸(C18∶2n-6)比对凡纳滨对虾（Litopenaeus vannamei）幼虾生长性能和脂肪酸组成的影响。采用鱼油、亚麻油和豆油作为脂肪源，以不同的比例配制4种粗脂肪水平约为7.2%的等氮饲料，饲料中C18∶3n-3/C18∶2n-6比值为0.17、0.30、0.56和0.68。选用平均体重为（0.573±0.002） g的凡纳滨对虾幼虾480尾，随机分为4组(每组3个重复，每个重复40尾虾），分别记为L0.17、L0.30、L0.56和L0.68。试验期为8周。结果显示，随着饲料中C18∶3n-3/C18∶2n-6比的升高，凡纳滨对虾幼虾增重率呈现先升高后降低的趋势，而饲料系数则呈现先下降后上升的趋势，但组间的差异均不显著（P>0.05）。通过二元回归分析得出增重率（y）与C18∶3n-3/C18∶2n-6比（x）的关系为y=－1 333.2x2+1 175.5x+785.66（R2=0.723 8），并得出当C18∶3n-3/C18∶2n-6比为0.44时，增重率最高。全虾粗蛋白质含量以L0.68组为最高，显著高于其他3组（P<0.05）。全虾水分和粗脂肪含量以及肝胰指数组间差异均不显著（P>0.05）。各组对虾肌肉中C18∶2n-6和C18∶3n-3含量低于它们在肝胰腺中的含量，而C20∶4n-6、C20∶5n-3（EPA）、C22∶6n-3（DHA）在肌肉中的含量高于其在肝胰腺中的含量。L0.68组肝胰腺EPA含量显著高于L0.30组（P<0.05），DHA含量显著高于其他3组（P<0.05）。肌肉EPA、DHA含量以L0.30组最高，但组间差异不显著（P>0.05）。由此得出，饲料中C18∶3n-3/C18∶2n-6比一定程度地影响凡纳滨对虾幼虾的生长性能，显著影响肝胰腺和肌肉中C18∶3n-3和C18∶2n-6系列脂肪酸的含量。以增重率作为判定指标，建议饲料中C18∶3n-3/C18∶2n-6比值为0.44。

This experiment was conducted to study the effects of different dietary linolenic acid (C18∶3n-3)/linoleic acid (C18∶2n-6) ratios on growth performance and fatty acid composition of juvenile Litopenaeus vannamei. Four isonitrogenous diets with crude fat level at about 7.2% were formulated using three different lipid sources (fish oil, linseed oil and soybean oil) in variable proportions to prepare diets with different C18∶3n-3/C18∶2n-6 ratios of 0.17, 0.30, 0.56 and 0.68, respectively. Four hundred and eighty juvenile Litopenaeus vannamei with an average body weight of (0.573±0.002) g were randomly divided into 4 groups (3 replicates per group and 40 shrimp each replicate), and remarked L0.17, L0.30, L0.56 and L0.68. The experiment lasted for 8 weeks. Results showed as follows: with the C18∶3n-3/C18∶2n-6 ratio increasing, weight gain rate of shrimp was increased firstly and then decreased while feed conversation rate was decreased firstly and then increased, but the difference was not significant among all groups (P>0.05). According to the bivariate regression analysis, the relationship between the weight growth rate (y) and the C18∶3n-3/C18∶2n-6 ratio (x) as was y=－1 333.2x2+1 175.5x+785.66 (R2=0.723 8). As C18∶3n-3/C18∶2n-6 ratio was 0.44, juvenile shrimp showed the highest weight gain rate. The highest crude protein content of the whole body was found in L0.68 group which was significantly higher than that in other groups (P<0.05). There was no significant difference on moisture and crude fat contents of the whole body and hepatopancreas index among all groups (P>0.05). The contents of C18∶2n-6 and C18∶3n-3 in muscle of all groups were lower than those in hepatopancreas, but the contrary was for the contents of C20∶4n-6, C20∶5n-3 (EPA) and C22∶6n-3 (DHA). The content of EPA in hepatopancreas in L0.68 group was markedly higher than that in L0.30 group, and the content of DHA in hepatopancreas in L0.68 group was significantly higher than that in other groups (P<0.05). In muscle, the highest contents of EPA and DHA were found in L0.30 group, but no significant difference was found among all groups (P>0.05). In conclusion, the dietary C18∶3n-3/C18∶2n-6 ratio affects the growth performance of juvenile Litopenaeus vannamei to a certain extent, and significantly affects contents of C18∶2n-6 and C18∶3n-3 set fatty acids in hepatopancreas and muscle of juvenile Litopenaeus vannamei. When dietary C18∶3n-3/C18∶2n-6 ratio is 0.44, juvenile shrimp show the best growth performance.［Chinese Journal of Animal Nutrition, 2010，22（5）:1413-1421］