Abstract

Hormonal manipulation is a common spawning technique in aquaculture. In the present study, 15 male grass carp (Ctenopharyngodon idellus) with mean weight of 5 kg and 30 females with mean weight of 8 kg were used. Broodstock were injected with ovaprim (salmon gonadotropin- releasing hormone analogue in combination with domperidone) and human chronic gonadotropin (HCG) with a dosage of 4 mg for female/kg BW and 2 mg for male/kg BW in 2 injections at 24 h interval. At zero time, blood samples were taken from male and females and testosterone, estradiol, cortisol and glucose levels were measured and used as control values. Administration of hormones accelerated the final oocyte maturation and induced ovulation. Plasma levels of estradiol (E2) in female grass carp increased sharply at 6 h after the first injection and decreased after the second injection. Serum testosterone (T) in males increased parallel to the plasma estradiol in females. Also, the results show significant increase in the serum cortisol and glucose values during the artificial spawning period (P<0.05).

Key words: GnRHa, human chronic gonadotropin (HCG), sex steroid, cortisol, glucose, induced spawning, grass carp.