Cryopreservation of Prochilodus lineatus semen: effect of cryoprotectants combination

Abstract

The study was conducted with the objective of comparing the toxicity and the effect of the combination of intra and extracellular cryoprotectants in curimba Prochilodus lineatus sperm cells subjected to cryopreservation. Semen from 19 males were analyzed and diluted in four solutions comprised of intra and extracellular cryoprotectants in the following combinations: methanol + lactose, methanol + egg yolk, DMSO + lactose; and DMSO + egg yolk. A portion of the diluted semen was frozen while the remaining fraction was kept in repose and evaluated after 10 min. For freezing, the diluted samples were packaged in 0.50 mL straws and placed into liquid nitrogen vapor for 24 h and, after this time, submerged into liquid nitrogen for 10 days. The combination of DMSO + lactose was less toxic to the diluted semen, resulting in higher motility rates and durations when compared to the other treatments. After thawing, the highest motility rate and duration were obtained using lactose as extracellular cryoprotectant, regardless of its combination. There was no significant difference between treatments when analyzing sperm morphology after thawing. Considering the effects of the tested treatments, the use of lactose as an extracellular cryoprotectant added with DMSO or methanol is the most suitable, since these combinations presented the highest motility rates and durations and low morphological change rate after thawing.