| Popis: |
The present study describes a new method for fertilization of large egg batches with cryopreserved semen in the rainbow trout (Oncorhynchus mykiss). Egg batches of 500 g were inseminated with semen frozen in sixteen 1.2-ml straws (sperm/egg ratio=2.7×106:1). To be able to handle this number of straws at the same time, they were connected in self-made, flexible plastic racks into “straw packages”. The straws were filled with diluted semen, and the whole straw packages frozen in the vapor of liquid nitrogen are 1 cm above the surface of liquid nitrogen. As the racks remained flexible in liquid nitrogen, the straw packages could be rolled together for storage in cans of commercial liquid nitrogen containers. For thawing, the straw packages were rolled out and thawed in warm water (30 °C, 30 s). Then, they were placed over the eggs and the straws were cut open to release the semen. The semen was mixed with the eggs and, thereafter, 250-ml fertilization solution was added under constant mixing. The fertilization rates were 87.5±1.6% (n=3) when inseminating 500-g egg batches with cryopreserved semen and 86.7±2.2% for the fresh semen controls. Only the dry fertilization technique yielded high fertilization rates when inseminating large egg quantities with cryopreserved semen, while other investigated parameters (amount of fertilization solution, arrangement of eggs) had no influence. |
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