Location: Warmwater Aquaculture Research UnitTitle: Evaluation of a gonadotropin releasing hormone analog of cGnRH II as a spawning aid for channel catfish versus analogs of mGnRH I and sGnRH III Author
Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2014
Publication Date: 6/26/2014
Citation: Quiniou, S., Bosworth, B.G., Chatakondi, N.G., Oberle, D.F. 2014. Evaluation of a gonadotropin releasing hormone analog of cGnRH II as a spawning aid for channel catfish versus analogs of mGnRH I and sGnRH III. North American Journal of Aquaculture. 76(3):281-288. Interpretive Summary: During the last decade, the catfish industry has started using hybrid (channel x blue) catfish rather than just channel. However, inefficiencies in hybrid fry production need to be addressed to increase the supply of hybrid catfish needed by the industry. The effectiveness of three different analogs of gonadotropin-releasing hormone (GnRH) to induce spawning in female channel catfish was evaluated head to head. cGnRH IIa showed the highest mean percent ovulation (90.2%), followed by mGnRH Ia (64.9%) and then sGnRH IIIa (44.3%) for an equal egg quality and embryo viability. Therefore, cGnRH IIa shows great potential to increase hybrid production.
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 Investigative New Animal Drug 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 II, previously thought to have only secondary roles in reproduction compared to type I and III, 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 cGnRH IIa having the highest ovulation (90.2%), followed by mGnRH Ia (64.9%) and then sGnRH 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 total injected 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.