Hormonal changes in male white bass (Morone chrysops) and evaluation of milt quality after treatment wit

摘要: Abstract Captive white bass ( Morone chrysops ) were exposed to an increase in temperature and treated with a gonadotropin-releasing hormone agonist (GnRHa) delivery system during the spermiation period. Circulating levels of various reproductive hormones, milt production quality examined before after GnRHa treatment. gonadotropin II (GtH II) prior treatment below assay detection limit (0.4 ng ml −1 ), while mean (± SEM) plasma 17α, 20β-dihydroxy-4-pregnen-3-one (17, 20β-P) 0.09 ± 0.03 , testosterone (T) 0.79 0.11 11-ketotestosterone (11-KT) 1.7 0.3 . Treatment induced significant increases GtH 17,20β-P 7 days, whereas T 11-KT unaffected. Plasma 20β, 21-trihydroxy-4-pregnen-3-one 21-P) remained unchanged experiment 0.55 0.05 Mean total expressible increased significantly system, from 2.0 0.1 kg body weight on day 0 3.6 0.5 7. Milt constant saline-injected control fish averaged 2.1 0.2 Sperm density, motility fertilization percentage inseminated eggs did not differ between GnRHa- fish, 52 2 × 10 9 spermatozoa 50 4% motile 60 5% fertilized eggs, respectively. These results demonstrate effectiveness sustained enhancing bass, without negatively affecting quality. It is assumed that enhancement caused by high circulating levels, via action 17, 20β-P.