Effect of Freezing Techniques, Extenders and Cryoprotectants on the Fertilization Rate of Frozen Rainbow Trout (oncorhynchus Mykiss) Sperm

Rainbow trout (Oncorhynchus mykiss) sperm was frozen in liquid nitrogen in straws or as pellets on dry ice and stored in liquid nitrogen until artificial insemination. Sperm was diluted with one of three extenders containing 15% DMSO or 15% DMA as a cryoprotectant at a ratio of one part sperm to two parts extender. The straws were thawed in a water bath while the frozen pellets were thawed in their own extenders at 30oC for 30 s. For both freezing methods, the best fertilization results were obtained with extender III containing 15% DMSO, 52.3% (56.3% of the control) for sperm frozen in straws and 48.4% (52.4% of the control) for sperm frozen as pellets. The interaction between extender and cryoprotectant was statistically significant (p<0.05). Introduction Cryopreserved fish sperm can be used for genetic improvement through selective breeding, production of reference stocks and hybrids, and reduction of the number of broodstock and labor involved in maintaining them. Cryopreserved sperm can help to protect stocks from total elimination due to sudden disease by allowing the introduction of new genetic lines with a reduced risk of transmitting unknown pathogens to cultured fish * Corresponding author. E-mail: [email protected]