Cryoprotective effect of antifreeze polyamino-acid (Carboxylated Poly-l-Lysine) on bovine sperm: A technical note

In this study, investigating Carboxylated Poly-l-Lysine (CPLL) for its effectiveness as a new cryoprotectant for bovine sperm is aimed. CPLL is an ampholytic polymer compound, has cryoprotective properties similar to those of anti-freeze protein. The cryopreservation medium used for control group consisted of 6.5% (v/v) glycerol, the cryopreservation medium used for experimental group consisted of 3.25% (v/v) glycerol + 0.5% (w/v) CPLL. There was no consequential difference in sperm motility parameter after thawing whereas there was huge distinction for sperm membrane integrity rate (control vs experimental; 49.6 vs 60.7%, P < 0.01). Conception rate of artificial insemination of experimental group was significantly higher than that of control group (79.0% vs 53.1%, P < 0.01). These results suggest CPLL has protected sperm membrane and leads to improve fertility. This is the first report using CPLL for bovine sperm cryopreservation, it is also expected CPLL can be applied to other animal species.