INDUCED SPAWNING OF SILVER CARP, Hypophthalmichthys molitrix USING HORMONES/HORMONAL ANALOGUE WITH DOPAMINE ANTAGONISTS

A study was made to investigate the effects of using carp pituitary extract, human chorionic gonadotropin, luteinizing hormone releasing hormone analogues (Receptal), with or without dopamine antagonists on the spawning performance parameters of silver carp. Results of the current study indicted successful induction of spawning silver carp using different spawning agents. The breeding response and fecundity were comparable among all treatment groups. Moreover, the current experiment clearly indicated that the use of hCG, or mammalian LNRH together with dopamine antagonists was more effective in induction of ovulation and increasing fecundity and hatching rate compared to the other spawning stimulators used in the current study. The results also demonstrated that using dopamine inhibitors potentiate the effect of the hormones used for spawning induction together with reduction of its dose (i.e. dose of carp pituitary extract, human chorionic gonadotropin). Meanwhile, it is well established that domperidone is preferred than metoclopramide as a dopamine antagonists for spawning induction of fish. In view of these results it is clear that not only carp pituitary extract and human chorionic gonadotropin but also the mammalian LHRH analogue (i.e. Receptal) was effective to induce spawning in silver carp. This is important in the view of the fact that mammalian LNRH analogues are available more widely and their price is much more attractive. This would result in cost reduction of induced breeding by using mammalian LNRH analogues in combination with a dopamine antagonist or alone.