Technical University of Denmark, National Institute of Aquatic Resources, Kgs. Lyngby, Denmark.
Centre of Marine Sciences, Universidade Do Algarve, Faro, Portugal.
Fish Physiol Biochem. 2022 Feb;48(1):185-200. doi: 10.1007/s10695-021-01042-4. Epub 2022 Jan 19.
Egg biochemical composition is among the main factors affecting offspring quality and survival during the yolk-sac stage, when larvae depend exclusively on yolk nutrients. These nutrients are primarily embedded in the developing oocytes during vitellogenesis. In aquaculture, assisted reproduction procedures may be applied enabling gamete production. For the European eel (Anguilla anguilla), reproductive treatment involves administration of pituitary extracts from carp (CPE) or salmon (SPE) to induce and sustain vitellogenesis. In the present study, we compared the influence of CPE and SPE treatments on offspring quality and composition as well as nutrient utilization during the yolk-sac stage. Thus, dry weight, proximal composition (total lipid, total protein), free amino acids, and fatty acids were assessed in eggs and larvae throughout the yolk-sac stage, where body and oil-droplet area were measured to estimate growth rate, oil-droplet utilization, and oil-droplet utilization efficiency. The results showed that CPE females spawned eggs with higher lipid and free amino acid contents. However, SPE females produced more buoyant eggs with higher fertilization rate as well as larger larvae with more energy reserves (estimated as oil-droplet area). Overall, general patterns of nutrient utilization were detected, such as the amount of total lipid and monounsaturated fatty acids decreasing from the egg stage and throughout the yolk-sac larval stage. On the contrary, essential fatty acids and free amino acids were retained. Notably, towards the end of the yolk-sac stage, the proximal composition and biometry of surviving larvae, from both treatments, were similar.
卵的生化组成是影响蛋黄囊期幼体质量和生存的主要因素之一，在此期间，幼虫完全依赖卵黄中的营养物质。这些营养物质主要在卵母细胞的卵黄生成过程中嵌入其中。在水产养殖中，可以应用辅助生殖技术来生产配子。对于欧洲鳗鲡（Anguilla anguilla），生殖处理包括使用鲤鱼（CPE）或鲑鱼（SPE）脑垂体提取物来诱导和维持卵黄生成。在本研究中，我们比较了 CPE 和 SPE 处理对后代质量和组成以及蛋黄囊期营养物质利用的影响。因此，在蛋黄囊期，评估了卵和幼虫的干重、近侧组成（总脂质、总蛋白）、游离氨基酸和脂肪酸，测量了身体和油滴面积，以估计生长率、油滴利用和油滴利用效率。结果表明，CPE 组产卵的卵中脂质和游离氨基酸含量较高。然而，SPE 组产卵的卵具有更高的浮力，受精率更高，幼虫更大，能量储备更多（估计为油滴面积）。总体而言，检测到了营养物质利用的一般模式，例如总脂质和单不饱和脂肪酸的量从卵期开始减少，并贯穿蛋黄囊期幼虫阶段。相反，必需脂肪酸和游离氨基酸得以保留。值得注意的是，在蛋黄囊期结束时，来自两种处理的存活幼虫的近侧组成和生物测量结果相似。
