Usability of a syntethic antrifreeze protein carboxylated poly L-lysine for frozen storage of goat sperm

Objective: The aim of this study was to investigate the possibilities of using CPLL (Carboxylated Poly-L-lysine), which is known as an artificial antifreeze protein analogue, to reduce the amount of glycerol in the extender used in goat semen freezing. Material and Methods: In this study, 5 sexually mature Saanen goats aged 18-24 months and 45-55 kg body weight, which were kept in the farm animals pen of Adnan Menderes University, Faculty of Veterinary Medicine, were used for semen collection. The study was performed on semen samples of freezable quality (containing ≥ 70% motile spermatozoa and abnormal spermatozoa ≤ 20%) obtained by artificial vagina. In the extender containing either 3.5% glycerol with 0, 0.2, or 0.5 CPLL, or 5% glycerol added 0, 0.2, or 0.5% CPLL sperm samples were frozen and thawed at least 5 times. Sperm motility, viability, morphology, premature acrosome reacted sperm rate, and membrane integrity were evaluated. The data obtained were analysed by One Way ANOVA following Post Hoc Tukey test in SPSS© 22.0 programme for analysis and the data were presented as mean±SEM. Significant differences were determined at P < 0.05 level. Results: In the statistical analysis, no significant differences P < 0.05 were found between the groups in terms of motility, viability assessed by eosin-nigrosin staining, morphology, premature acrosome reacted sperm rate, and the membrane integrity.. Conclusion: It is well known that high glycerol concentrations in the extender may have toxic effects. Although no statistical differences were observed between the groups in the present study, the possibility of combining CPLL with different cryoprotectants still exists. Each of these combinations may form the basis for new research topics regarding their effects on fertility levels.