Effect of cryopreservation on sperm motility parameters and fertilizing ability of brown trout semen

The aim of this study was to test the usefulness of 0.18 M glucose in 9% methanol as an extender, the ratio 1:5 (semen:extender) and an equilibration time of 15 min for the brown trout semen cryopreservation (n = 9). The final concentration was 0.15 M and 7.5% for glucose and methanol, respectively. Sperm motility parameters and fertilization rate at the eyed and hatching stages were assessed for post-thaw semen. The applied cryopreservation procedure resulted in remarkably high (73.8%) post-thaw sperm motility. The fertilization rate of cryopreserved brown trout semen was over 90% for sperm-to-egg ratios of both 300 000 and 600 000:1. To our knowledge, this study is the first to report the remarkably high post-thaw fertilization ability of brown trout semen at a sperm-to-egg ratio as low as 300 000:1. The described procedure for brown trout cryopreservation is highly reliable and efficient and therefore can be recommended for hatchery practice after scaling up this technique. (C) 2014 Elsevier B.V. All rights reserved.