The present study was conducted to evaluate the effect of carp pituitary extract (CPE) alone, and Cystorelin (GnRh),Receptal (Buserelin acetate) with or without dopamine receptor antagonist (Dompridone or Metoclopramide) for induction of spawning in silver carp (Hypothalamichthys molitrix). The experiment was conducted in the Fish Hatchery, Central Laboratory for Aquaculture Research (CLAR), Abbassa, Sharkia, Egypt in May 2013. Thirty five silver carp were divided into 7 groups. Spawning rate, latency time, mass of eggs, egg weight index percentage (EWIP). Ovulation rate, cost of injection, return and economic efficiency were recorded. Results showed successful induction of spawning in silver carp with variable ovulation rate. Ovulation rate was significantly high (100%) in groups 4,5,6,7 which injected Cystorelin or Receptal combined with dopamine antagonists. Also, ovulation rate in group (1) receiving CPE (100%). While ovulation rate was 0% and 40% in groups (2, 3) respectively which injected Receptal alone or that treated with receptal 0.4 ml/Kg b.w. in double injections combined with dopamine antagonists (Metoclopramide). Moreover, the results showed that not only carp pituitary extract but also Receptal and Cystorelin with Dompridone or Metoclopramide were effective in induction of spawning in silver carp. The price of Cystorelin is much more economic than Receptal (Buserelin acetate). The present study suggests that Cystorelin with dopamine antagonist complex might be considered best substitute for pituitary extract during induced breeding. |
