Location: Warmwater Aquaculture Research Unit
Title: Evaluation of a GnRh-II analog as a spawning aid in catfish Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 2, 2013
Publication Date: N/A
Technical Abstract: The effectiveness of three different analogs of gonadotropin-releasing hormone (GnRH) to induce spawning in female channel catfish, Ictalurus punctatus, was evaluated head to head in a blind study. Two of those analogs are currently used under INAD by the catfish industry, mGnRH Ia (D-Ala6, Pro9-NHet) and sGnRH IIIa (D-Arg6, Trp7, Leu8, Pro9-NHet). A third analog, cGnRH IIa (D-Arg6, Pro9-NHet) derived from a different type of GnRH, type 2, previously thought to have only secondary roles in reproduction compared to type 1 and 3, was also evaluated. The study was divided into four independent, weekly trials over the course of the spawning season. Seventy-eight females were used per treatment. Each female received two hormone doses, one for priming and one for induction (mGnRH Ia and cGnRH IIa: 20µg/kg and 80µg/kg; sGnRH IIIa: 2µg/kg and 8µg/kg). Treatment had a significant effect on the mean percent ovulation with GnRHIIa having the highest ovulation (90.2%), followed by mGnRH Ia (64.9%) and then GnRH IIIa (44.3%). There were no differences among treatments for eggs or fry per kg of female when only ovulated females were considered, indicating that the differences among treatments for eggs and fry per kg for all females reflected hormone effects on ovulation rate and not differences in egg quality or fertility. Therefore, cGnRH IIa shows great potential as a spawning aid for channel catfish outperforming mGnRH Ia and sGnRH IIIa.