Studies on the Requirement and Nutritional Role of Marine Fish Larvae for EPA and DHA

为了解海水鱼仔鱼对二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)的营养需求及其营养作用，本研究首先采集了不同发育阶段的仔鱼，并对其脂肪酸组成进行了分析。只有3种鱼的DHA含量在孵化后即刻下降。其次，本实验采用直接法比较了卤虫幼体中脂肪和n-3HUFA在不同类型油脂中的掺入量，如乙酯(EE)、甘油三酯(TG)、甲酯(ME)和游离脂肪酸(FFA)，其中n-3HUFA含量约为43%。结果表明，在卤虫体内，用EE富集24小时可获得最大的n-3HUFA掺入量，且EE或ME很快被…更多的被合并到TG组分中。然后将这些卤虫饲养在条纹刀口和红鱼幼体上，根据这两种鱼的生长、存活和化学成分，比较不同类型油脂富含的卤虫的食用价值。结果表明，添加甘油三酯、ME和EE能有效提高卤虫对这两种鱼的饲料价值，其中以EE的效果最为显著。其次，研究了富含EE型EPA和DHA的卤虫对黄鱼和罗非鱼幼体的饲料价值。以富含EPA的无节幼体为食的黄尾和红鱼幼体生长良好，成活率高，但活性较低。另一方面，以富含DHA的卤虫为饲料的鱼表现出高的饲料性能。高活性测试。由此可见，幼鱼需要DHA才能获得良好的生长和健康。最后，通过两次饲养实验，比较了EPA和DHA对幼鱼EPA和DHA的必需脂肪酸(EFA)值。这两种鱼的饲料中都没有添加EFA，表现出低饲料效率和高死亡率。预计幼鱼饲料中EPA和DHA的需要量分别为1%和0.5%左右。DHA的全民教育效率也是EPA的两倍。另一方面，对幼鱼的EFA实验表明：1)DHA作为EFA比EPA更有效；2)饲料中仅DHA的需要量约为1.7%。这一研究清楚地表明，海水鱼幼鱼需要DHA作为EFA和生理用途。较少

This study was investigated the requirement and nutritional role of marine fish larvae for icosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).At first, different stages of larval fish such as striped jack, yellowtail, cod were collected and analysed their fatty acid compositions. Only DHA content in three species was decreased immediately after hatching. This result suggests that fish larvae during 5-10mm size (total length) may require high amount of DHA.Secondly, the experiment was conducted to find out a suitable lipid type for enrichment by comparing the incorporation of lipid and n-3highly unsaturated fatty acids (n-3HUFA) in Artemia nauplii between various types of oil, such as ethylesters (EE), triglycerides (TG), methyl esters (ME), and free fatty acids (FFA) containing about 43% of n-3HUFA, using the so-called direct method. It is concluded that a maximum incorporation of n-3HUFA in Artemia can be obtained by enrichment with EE for 24h and that EE or ME are very quickly … More incorporated into TG fractions. Then these Artemia were fed on larval striped knife jaw and red sea bream to compare the dietary value of Artemia enriched with various types of oil, based on the growth, survival and chemical compositions of both fish larvae. The result indicated that the dietary value of Artemia to both species was effectively improved by enrichmewith TG, ME, and EE, especially with EE.In next, dietary value of Artemia enriched with EE type of EPA and DHA for larval yellowtail and red sea bream was investigated. Both larval yellowtail and red sea bream fed on nauplii enriched with EPA showed good growth and high survival rate, however quite low activity tests were observed. On the other hand, fish fed DHA enriched Artemia showed high feed performances, incl. high activity tests. Thus, it is clearly indicated that larval fish require DHA in order to receive good growth and health.Finally, two feeding experiments were conducted to compare the essential fatty acids (EFA) value between EPA and DHA in juvenile red sea bream and striped jack. Both fish fed a diet without supplemental EFA showed low feed efficiency and high morthlity. The requirement of EPA and DHA was estimated to be around 1% and 0.5% in diet for juvenile red sea bream, respectively. The EFA efficiency of DHA was also found to be twice as high as that of EPA. On the other hand, the experiment on the EFA of juvenile striped jack have demonstrated that : 1) DHA is more effective than EPA as EFA ; 2) requirement for DHA alone is about 1.7% in diet.This study was clearly demonstrated that marine fish larvae require DHA as EFA and physiological purpose. Less