摘要：
Fatty acid composition and content were analyzed in juvenile (0+age) American shad Alosa sapidissima cultured in a 0.17 hm2 and 1.5 m depth shaded pond during different growth stages ( July－November) by biochemi-cal analysis methods to understand the lipid nutrition status and the changes in fatty acid composition. The moisture of American shad was shown to be significantly decreased with the growth ( P<0.05) , the total lipid contents being increased significantly from 12.93% in July to 35.05% in November with the growth ( P<0.05) . There were 8 satu-rated fatty acids ( SFA) , 7 mono－unsaturated fatty acids ( MUFA) , and 11 polyunsaturated fatty acids ( PUFA) in the dry samples of American shad in different growth stages ( July－November). The maximal C18:1n9c ( 27. 11%－36.87%) was observed in 0+ age American shad juvenile ( July－November), and the percent content of C16:0 (19.63%－25.33%) and C18:0(6.42%－7.46%) was decreased significantly with the growth of the fish. The C18:2n6c content (16.87%－22.95%) was increased first and then decreased with the growth, with the maximum (22.95%) in September, indicating that fatty acid composition of 0+age juvenile is closely related to the composition of the di-et. However, low levels of C16:0 and C18:0 in the diet led to a sustained decline in the levels of C16:0 and C18:0 in the 0+age juveniles. The diet containing low C18:1n9c(23.93%－24.04%) did not cause the decrease in C18:1n9c content in the juvenile. On the contrary, the C18:1n9c content in the juveniles was increased significantly from 27.11%in August to 36.87% in November, showing a negative correlation; high C18:2n6c content (45.52%－46.88%) in the diet did not result in enrichment of C18:2n6c(16.87% －22.95%). Lower levels of DHA (1.57%－1.79%) in diet resulted in a significant decline in the DHA in the juveniles, from 4.00% in August to 1.62% in November. The diet contai-ning low ∑n－3PUFA/∑n－6PUFA ratio ( 0.13－0.14) also significantly affected the variation in ∑n－3PUFA/∑n－6PUFA ratio in fish, with the ratio from 0.29 in July to 0.15 in November. It is suggested that diet of Ameri-can shad juveniles be appropriate increase in C18:1n9c and n－3PUFA ( especially DHA) , reduce in great proportion of C18:2n6c, and adjust and increase the ratio of ∑n－3PUFA/∑n－6PUFA.%为了调查池养美洲鲥Alosa sapidissima当年鱼种 (0+龄幼鱼) 的脂类营养状况及脂肪酸组成的变化规律,采用生化分析手段,分析了遮荫池塘 (面积为0. 17 hm2,水深1. 5 m) 养殖的美洲鲥0+龄幼鱼不同生长阶段 (7—11月) 的鱼体脂肪酸组成及含量变化.结果表明: 美洲鲥当年鱼种鱼体的水分含量随着生长而显著降低 (P<0. 05),鱼体干质量的总脂肪含量随生长而显著升高 ( P<0. 05),总脂肪含量从7月的12. 93%显著增加到11月的35. 05%;美洲鲥当年鱼种不同生长阶段 (7—11月) 的鱼体干样中检出8种饱和脂肪酸 (SFA)、 7种单不饱和脂肪酸 (MUFA) 和11种多不饱和脂肪酸 (PUFA);从数值上看,各月份美洲鲥当年鱼种的C18:1n9c含量均为最高 (27. 11%~36. 87%), C16:0和C18:0含量 (分别为19. 63%~25. 33%和6. 42%~7. 46%) 随生长而显著下降 (P<0. 05),而C18:2n6c含量 (16. 87%~22. 95%) 随着生长呈现先上升后下降趋势,最高点出现在9月 (22. 95%);美洲鲥当年鱼种体内脂肪酸组成与其摄食的饲料成分密切相关,但也不是绝对的;较低C16:0和C18:0含量的饲料导致了鱼体内的C16:0和C18:0含量持续下降,呈现正相关;而较低C18:1n9c含量 ( 23. 93%~24. 04%) 的饲料未造成鱼体内 C18:1n9c含量下降,相反地,鱼体内的C18:1n9c含量从 8 月的 27. 11%显著上升到 11 月的 36. 87% ( P<0. 05),呈现负相关;较高 C18:2n6c含量(45. 52%~46. 88%) 的饲料未造成鱼体内富集C18:2n6c (16. 87%~22. 95%),呈现无显著相关;较低DHA含量 (1. 57%~1. 79%) 的饲料造成鱼体内 DHA 比例下降,含量从 8 月的 4. 00%显著下降到 11 月的1. 62% (P<0. 05);较低∑n－3PUFA/∑n－6PUFA比值 (0. 13~0. 14) 的饲料也严重影响了鱼体内∑n－3PUFA/∑n－6PUFA比值的变化趋势,比值从7月的0. 29显著下降到11月的0. 15 ( P<0. 05).研究表明,美洲鲥当年鱼种配合饲料中可适当增加C18:1n9c和n－3PUFA (特别是DHA) 的比例,大幅减少C18:2n6c的比例,调整提高∑n－3PUFA/∑n－6PUFA比值.
