Induction of ovulation in liza ramada (RISSO, 1826)‎ out of season

الملخص EN

The present work was designed to determine the suitable hormonal requirements for induction of ovulation in the thin-lipped grey mullet (Liza ramada) reared in brackish water earthen pond out of season.

On April 2014, eight groups of grey mullet (6 females / group) were collected and kept in aquaculture pond.

The first group (G1) did not receive the hormonal treatment.

The mullets of the other seven groups were subjected to intramuscular injection of hormones as follows: G2, 4500 IU/Kg human chorionic gonadotropin (hCG); G3, 3 mg melatonin (ML) /fish; G4, 3 carp pituitary extract (cPE) / fish; G5, a combination of 4500 IU/Kg hCG + 3 cPE / fish; G6, a combination of 4500 IU/Kg hCG + 3mg/ ML fish; G7 , a combination of 4500 IU/Kg hCG + 3 adrenal gland (AD) / fish; G8, a combination of 3 cPE + 3mg/ ML fish.

The results after 24 hr., of injection revealed that estradiol 17- β (E2) level in the collected serum experimental mullets was increased (P < 0.05) with G2 treatment.

In the same trend, gonadosomatic index (GSI) was significantly (P < 0.05) increased with G2.

The serum Progesterone (P) concentration and Progesterone/Estradiol 17-β ratio (P/E2) were significantly (P < 0.05) increased with G5 than other groups.

The G5 group showed oocytes maturation and ovulation superior to that of all other groups, with ripped oocyte and other different maturity stages in Liza ramada out of season.

It could be concluded that, 4500 IU/kg of hCG and 3 cPE combination had successfully induced the oocyte maturation in Liza ramada fish reared in brackish water under captivity out of season and a higher dose would induce the ovulation and spawning.