Disaccharide supplementation of extenders is an effective means of improving the cryopreservation of semen in sturgeon

Abstract

Sperm damage can be alleviated by optimizing the types and levels of cryoprotectants (including sugars) added to the extender to protect the sperm cells during freezing. This study was conducted to elucidate the effect of different disaccharides (maltose, lactose, trehalose and lactulose) upon the motility parameters of cryopreserved semen and the post-thaw storage of semen from Persian sturgeon, Acipenser persicus and Beluga sturgeon, Huso huso. Semen samples were diluted 1:5 in 9% methanol containing 0.2M maltose, trehalose, lactose or lactulose. Then, semen was equilibrated for 10min on ice and submerged in liquid nitrogen. After thawing (40°C, 5s) semen was stored for 0, 15, 30 and 60min at 4°C and semen motility investigated. For both sturgeon, the type of disaccharide had no effect on the duration of semen motility (expressed as curvilinear velocity, VCL). From the four disaccharides tested, lactulose exhibited the lowest sperm percentage. Furthermore, for all four disaccharides, cryopreserved semen motility was not affected by storage times of up to 30min maximum; however, after 60min of storage, a significant reduction was observed. Consequently, the best results were achieved with the disaccharides featuring glucose in their composition. In other words, maltose, lactose and trehalose can be used successfully for the cryopreservation of sturgeon semen.