Chapters authored
Long‐Term Storing of Frozen Semen at −196°C does not Affect the Post-Thaw Sperm Quality of Bull Semen
Today, it is theoretically assumed that frozen storage of semen doses in liquid nitrogen guarantees sperm functionality indefinitely. However, there are few studies that objectively evaluate the effects of long‐term storage on sperm quality parameters. In this study, we show a freezability analysis of bull semen stored for 1, 10, 25, 40 and 45 years at −196°C. Sperm viability and full sperm motility were analyzed by CASA system, and acrosome integrity was assessed with Coomassie blue staining. Our results showed that sperm viability and total sperm motility were not affected by long‐term cryopreservation at −196°C. Specifically, we did not find any significant differences (p > 0.05) associated between different long‐time storing analyzed; both parameters showed optimal values of sperm viability and total sperm motility (both over 60%). Additionally, the acrosomal integrity parameter was not affected, showing an optimal range (87±1.6 - 95±0.5%). We conclude that the sperm quality of bovine semen is not affected by long-term storage at −196°C. However, future field trials will be necessary in order to validate that both fertility and embryo viability are maintained for the times analyzed.
Part of the book: Cryopreservation in Eukaryotes