Effect of freezing rate on goat sperm morphology and DNA integrity

Abstract

This study investigates the effect of freezing rates on the spermatological parameters of frozen and thawed Saanen goat semen. Equilibrated semen was frozen at 4 different freezing rates from +5 °C to -150 °C (G10: 10 °C/min, G12: 12 °C/min, G15: 15 °C/min, and G24: 24 °C/min) and stored in liquid nitrogen until use. Semen samples were examined for sperm motility, defective acrosomes (FITC-PSA), and DNA integrity using TUNEL after dilution with extender A at equilibration and postthaw stage. There was no significant difference among the freezing stages in terms of DNA fragmentation (P > 0.05). DNA integrity was partially affected by the freezing rate. The increase of freezing rate from 10 °C/min to 24 °C/min between +5 °C and -150 °C resulted in higher postthaw DNA damage. The study found that the freeze-thawing process is detrimental to postthawed goat semen motility (P < 0.05), acrosome integrity (P < 0.05), and DNA integrity (P > 0.05). Although the freezing rates used in the present study had no effect on postthaw sperm motility and acrosome integrity (P > 0.05), sperm DNA integrity was affected.