Ovulation induction in northern pike Esox lucius L. using different GnRH analogues, Ovaprim, Dagin and carp pituitary

摘要

The traditional GnRH analogue treatments applying the chemicals in pure form proved to be ineffective in inducing ovulation in northern pike (Esox lucius L). Neither mGnRHa ([D-Ala(6) , Pro(9) NEt]-mGnRH) nor sGnRHa ([D-Arg(6) , Pro(9) -Net]-sGnRH) administered alone or together with pimozide (mGnRHa), metoclopramide (mGnRHa) or domperidone (sGnRHa) induced ovulation in females, whereas in groups receiving a carp pituitary injection most females ovulated. Spawning-inducing agent Dagin did not induce ovulation, whereas all but one female ovulated in the carp pituitary-treated group. Treatment with another preparation, Ovaprim, resulted in similar or lower ovulation ratio than treatment with carp pituitary. After the Ovaprim treatment, time to ovulation was not as predictable as after the carp pituitary injection. The mean fertilization rate was relatively low and similar in the groups treated with Ovaprim (54.7 +/- 12.3% and 58.7 +/- 19.1% for the first and second experiment respectively) and with carp pituitary (53.7 +/- 10.5% and 58.9 +/- 14.9%). The mean pseudogonadosomatic index (PGSI) was also similar between the Ovaprim-treated group (14.5 +/- 6.1%) and the carp pituitary-treated one (17.9 +/- 4.1%). In the present experiments, treatment with Ovaprim was less effective than that with carp pituitary.