Fertility and motility of sperm from Atlantic halibut (Hippoglossus hippoglossus) in relation to dose and timing of gonadotrophin-releasing hormone agonist implant

摘要: Abstract In broodstocks of Atlantic halibut, Hippoglossus hippoglossus , male and female gamete production often becomes unsynchronised towards the end spawning season—milt very viscous difficult to express while females are still producing batches good quality eggs. Gonadotrophin-releasing hormone agonist (GnRHa) has been shown stimulate spermiation in a number fish species. Therefore, we conducted two experiments where halibut were implanted intramuscularly with pellets containing GnRHa. The effect was tested at three periods: before, height spermiation. middle period, GnRHa doses (5 25 µg/kg bodyweight). Measurements made milt hydration, sperm motility fertilisation rate. Implanted males began least 4 weeks before control males. Both increased fluidity milt. This lasted for 20 days low dose group 40 high group. When applied ofthe season, reversed normal trend become more viscous. treatments did not affect rates obtained sperm. However, enhanced treated (25 μg/kg) compared controls. As described previously, plasma concentrations gonadal steroids, 5β-pregnane-3β,17,20β-triol 20-sulphate 17,20α-dihydroxy-4-pregnen-3-one, significantly by treatment. Concentrations testosterone on other hand decreased when spermiating Our data suggest that 17,20β-dihydroxy-4-pregnen-3-one or its metabolites involved possibly through affecting ion transport. Crown Copyright © 2004 Published Elsevier B.V. All rights reserved.