Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists

Attempts for increasing Astyanax altiparanae spawning rates and percentage of responsive oocytes

In this study, we aimed to propose changes in the protocol of cultured Astyanax altiparanae hypophysation to increase the maximum ovulation rate of 60% registered previously. To that two consecutive experiments were conducted. In the first experiment, three carp pituitary homogenate (CPH) doses (3, 6, and 9 mg/kg) were administered in a single injection, while in the second experiment, the 6 mg/kg CPH dose was tested either in single or double injections. In the first experiment, a single injection of 3 mg/kg CPH did not induce final oocyte maturation or spawning, while a dose of 6 mg/kg CPH resulted in an increase in the plasma level of prostaglandin (PGF_2α) at ovulation. The single higher dose of 9 mg/kg CPH did not improve reproductive performance and even though anticipated the resumption of meiosis it was detrimental to the spawning rate. In the second experiment, the dose of 6 mg/kg CPH fractionated into two injections led to a higher spawning rate, spawning volume per female body mass, frequency of post-ovulatory complexes, and PGF_2α concentration at ovulation compared to the single injection. The most effective treatment remained the 6 mg/kg of CPH fractionated into two injections, but still providing very low proportion of ovulated females (∼40 %). Overall, this study indicates that the spawning protocols for this species need to be improved to induce ovulation in a larger number of females and be more potent in those females that respond positively.

Comparison of artificial spawning effectiveness of hCG, CPH and GnRHa in combination with dopamine inhibitors in a wild strain of ide Leuciscus idus (L.) in hatchery conditions

Optimization of artificial reproduction, by increasing the survival rate of embryos and hatching rate, is of major importance for reducing genetic diversity, especially in fish captured from their natural habitat that subsequently spawn in hatcheries. The artificial reproduction of ide, Leuciscus idus (L.) was conducted in controlled conditions. The spawning agents included: different doses of human chorionic gonadotropin (hCG) that was compared with common carp pituitary homogenate (CPH), Ovopel - a commercial agent for induction of spawning that contains mammalian gonadotropin releasing hormone analogue (mGnRHa) with dopamine antagonists (DA): metoclopramide (MET) and Ovaprim - a commercial agent containing salmon gonadotropin releasing hormone analogue (sGnRHa) and a dopamine antagonists (DA): domperidone (DOM). There were no ovulations in females from control groups. There were no differences between the ovulation rates (90 %) or embryo survival (> 92 %) and hatching rates (> 91 %) when there was administration of hCG doses between 500 and 1000 IU/kg. When there was comparison of different spawning agents, the ovulation rate was 100 % for all treated groups. There were the shortest and longest latency times to the time of ovulation after administration of CPH (26 h) and hCG (79 h), respectively. The greatest embryo survival (> 93 %) and hatching (> 91 %) rates occurred as a result of hCG administration with these values being slightly greater than when there was treatment with Ovaprim. The association between latency time and hatching rate indicated that when there was a slower final oocyte maturation (FOM) there were greater hatching rates.