从锯缘青蟹幼体及其饵料的含脂情况探讨其脂营养需求

Nutritional requirement for lipid in larvae of mud crab, Scylla serrata

应用气相色谱仪和其他生化方法测定了锯缘青蟹幼体发育各发育期及其饵料轮虫和卤虫无节幼体的总脂含量、脂类组成和脂肪酸组成,为了解锯缘青蟹幼体的脂营养需求提供一些资料.结果表明,蚤状幼体的脂类含量随着发育逐渐增加,变态为大眼幼体后明显减少,说明幼体变态时对脂类有较高的营养需求.磷脂和胆固醇是幼体的脂类基本营养需求,轮虫和卤虫无节幼体基本上能满足幼体对饵料磷脂和胆固醇的需求.幼体的主要脂肪酸有16∶0,18∶1和20∶5n-3.在幼体发育过程中,高度不饱和脂肪酸20∶4n-6(AA)和20∶5n-3(EPA)的含量保持稳定,22∶6(DHA)则逐渐减少.笔者认为,饵料中DHA含量不足是影响幼体存活、发育和变态的关键因子之一.

Total lipid content, lipid classes and fatty acid composition in larvae of mud crab, Scylla serrata, and their diets, rotifer Brachionus plicalis and nauplii of Artemia were investigated by gas chromatograph and other biochemical methods to get some information on the nutritional requirement for lipid in Scylla serrata larvae. Total lipid content (percentage of dry weight)increased gradually during zoeal larvae stages, but decreased notably at megalopa stage, indicating a higher nutritional requirement for lipid during metamorphosis. The nutritional requirement of crab larvae for phosphatide and cholesterol which are the basal nutrition to crab larvae may be basally satisfied by the diets, rotifer and nauplii of Artemia. The main fatty acids in Scylla serrata larvae consisted of (16∶0), 18∶1 and 20∶5n-3. During the process of larvae development, the contents of two highly-unsaturated fatty acids, 20∶4n-6(AA) and 20∶5n-3(EPA), remained steady, while 22∶6n-3(DHA) reduced gradually. It is suggested that insufficient DHA content in diets might be a key factor affecting the survival, development and metamorphosis of Scylla serrata larvae.