National Institute of Oceanography and Fisheries, Alexandria, Egypt. mostafa
Anim Reprod Sci. 2010 May;119(1-2):115-22. doi: 10.1016/j.anireprosci.2009.12.014. Epub 2010 Jan 6.
The possibility of inducing and synchronizing spawning can be very useful to facilitate fish farming, particularly in species that achieve ovarian development in captivity without ovulation occuring. The present study was undertaken to observe the morphological and normal embryonic development of thin-lipped mullet, Liza ramada, after spawning induction of fish reared in freshwater fish farms. The use of pregnyl (HCG) as a priming injection at a dose of 20,000 IU/kg body weight followed by a second injection of 40,000 IU HCG/kg body weight 24 h later, proved to be effective in inducing final oocyte maturation, ovulation and spawning in L. ramada at 52-60 h after hormonal injection. The mean number of the ovulated eggs for each female was 700 +/- 80.3 eggsg(-1) body weight. The mean rates of buoyancy, fertilization and hatching were 46 +/- 7.1, 55 +/- 8.4 and 60 +/- 6.6, respectively. Fertilized eggs were kept under normal environmental conditions in seawater at 20-21 degrees C. The first cleavage occurred at 40 min, epiboly began at 5 h, the embryonic body was formed at 24 h and hatching occurred at 48 h after spawning. Newly hatched larvae were approximately 2.5 mm (total length) and similar to those of the other mullet species in terms of external features except no pigment spots were present over the yolk. The mouth and foregut opened on the 5th day after hatching; at which the total length of larvae was 3.5 mm; the hindgut and anus had developed prior to hatching. The induced ovulation technique using acute injections of hormones is an important step in the development of the mullet culture.
诱导和同步产卵的可能性对于促进鱼类养殖非常有用,特别是对于那些在圈养中能够实现卵巢发育但不会排卵的物种。本研究旨在观察在淡水养殖场养殖的鱼类进行产卵诱导后,薄唇鲻鱼(Liza ramada)的形态和正常胚胎发育。使用绒促性素(HCG)作为起始注射,剂量为 20,000 IU/kg 体重,24 小时后再注射 40,000 IU HCG/kg 体重,结果证明在激素注射后 52-60 小时,可有效诱导终末卵母细胞成熟、排卵和产卵。每个雌性排卵的平均卵子数为 700 +/- 80.3 个/克体重。受精率、孵化率和孵化率的平均值分别为 46 +/- 7.1%、55 +/- 8.4%和 60 +/- 6.6%。受精后的卵子在 20-21°C 的海水中保持在正常环境条件下。第一次分裂发生在 40 分钟,胚环开始于 5 小时,胚胎体在 24 小时形成,产卵后 48 小时孵化。刚孵化的幼虫约为 2.5 毫米(全长),在外部特征上与其他鲻鱼种类相似,只是卵黄上没有色素斑点。孵化后第 5 天,口和前肠张开;此时幼虫的全长为 3.5 毫米;在孵化前,后肠和肛门已经发育。使用激素急性注射诱导排卵技术是鲻鱼养殖发展的重要步骤。
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