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Submitted to: Aquaculture America Conference
Publication Type: Abstract Only Publication Acceptance Date: 11/1/2012 Publication Date: 2/21/2013 Citation: Chatakondi, N.G. 2013. Efficacy of salmon GnRHa to stimulate ovulation in channel catfish Ictalurus punctatus in hybrid catfish fry production. Aquaculture America Conference. P. 181. Interpretive Summary: Technical Abstract: Hormone manipulations for the induction of maturation and ovulation have made possible the control of reproductive processes in channel catfish and have contributed significantly to the production of hybrid catfish in the catfish industry. Hybrid embryo production requires more labor, resources, and a more regimented production schedule. The effective dose of currently used common carp pituitary and luteinizing hormone releasing hormone analog to induce spawn channel catfish in hybrid fry production is high and results in increased cost of producing hybrid catfish in hatcheries. Hence, there is a need to identify alternate hormones that are potent, reliable and cost-effective spawning agent to realize the potential of hybrid catfish in the catfish industry. The present study was designed to evaluate the minimum effective dose of salmon GnRH analogue (Des-Gly10-D-Arg6-Trp7-Leu8)-LHRH ethylamide to stimulate FOM and ovulation in channel catfish. Four levels of sGnRHa (0, 1, 5, 10 and 25 ug/kg BW) were compared with commonly used 100 ug mLHRHa/kg BW. Intraperitoneal injections were administered in 4-year old gravid channel catfish females selected from over 200 females captured by seining a pond, six females were randomly allocated to 5 hormone treatments. Hormone was administered 20% of the dose as the priming dose and 15h later, 80% of the hormone dose was administered as resolving dose. Individual fish were held in a soft mesh nylon bags that were suspended in a 10,000 L concrete vat supplied with continuous water and air. Ovulating females were stripped and the eggs fertilized with blue catfish sperm, fertilized eggs were water hardened and hatched in troughs. Oocyte samples were biopsied and 0.7 mL blood samples were withdrawn from individual females at 0, 24 and 36h after the hormone administration to determine the maturational profiles. Ovulation response of 10 or 25 µg sGnRHa/Kg did not differ (P > 0.05) with 100 µg mLHRHa/Kg BW, higher than 0 or 5 µg sGnRHa/Kg treatment. Mean latency, percent fertilization, fecundity, and fertilization did not differ (P > 0.05) among the treatments. Percent hatch and fry produced per kg of BW were higher (P < 0.05) in 10 µg sGnRHa /Kg BW and 100 µg mLHRHa/Kg BW compared to 0, 5, or 25 µg sGnRHa/Kg BW. The association of gonadal development with plasma levels of steroids from hormone induction to ovulation and implications of minimum effective dose of salmon GnRHa in hybrid catfish fry production will be discussed. |
