Single Injections of Human Chorionic Gonadotropin or Mammalian Gonadotropin Releasing Hormone Analog at Low Dosages Induce Ovulation in White Bass

Abstract

Spawning trials were conducted to determine an efficacious dosage of human chorionic gonadotropin (hCG) and to investigate the potential of mammalian gonadotropin releasing hormone analog (mGnRHa) to induce ovulation in white bass Morone chrysops. White bass broodstock were habituated to indoor tanks and subjected over several months to photoperiod-temperature regimes simulating the seasons to induce gonadal maturation. Various hCG dosages (0, 10, 25, 50, 150, 170, 250, 280, and 830 IU/kg body weight) were tested in single injections. We demonstrated that white bass can be successfully spawned with an hCG dosage as low as 50 IU/kg. However, this dosage did not result in all fish ovulating in a subsequent trial. We found no significant differences between 150 IU hCG/kg and higher dosages in ovulation response (ovulation success and time to ovulation), egg production (number of eggs/kg), or egg quality (fertility and hatch rates). Single injection of mGnRHa at 50 g/kg did not consistently cause ovulation in white bass. Use of pimozide, a dopamine antagonist, along with mGnRHa, did not significantly improve ovulation response, egg production, or egg quality in white bass. No significant differences existed in spawning response, egg production, or egg quality when 24-h and 48-h intervals between mGnRHa and hCG injections were used or between these protocols and hCG treatment alone. We recommend an hCG dosage at 150 IU/kg if ovulation is to be induced via a single hormone injection.

Differential Incorporation of Dietary Fatty Acids from Flax and Fish Oils into Lipid Classes of White Bass Ova

“…At the end of the feeding trial, total weight gain and survival were determined. Final ovum maturation and ovulation were induced by intramuscular injection of human chorionic gonadotropin (150 international units/kg; Suresh et al 2000).…”

Effects of Dietary Lipid and Fatty Acids on White Bass Reproductive Performance, Egg Hatchability, and Overall Quality of Progeny

“…Spawning and hatchery technique.-For synchronous spawning of all treatment groups, females were injected intramuscularly with human chorionic gonadotropin at a concentration of 150 international units/kg (see Suresh et al 2000) to induce ovulation. Individual females were weighed and then were manually stripped of their eggs and re-weighed.…”

Effect of dietary marine lipids on female white bass ova compositions and progeny survival

“…At the conclusion of the feed trial, intramuscular injections of 150 IU hCG/kg were administered to induce final oocyte maturation and ovulation (Suresh et al 2000). Beginning 24 h post-hCG injection, female fish were checked for ovulation every 2 h. Ovulation was determined to have occurred when light abdominal pressure produced free-flowing, clear yellow ova.…”