Successful ram semen cryopreservation with lyophilized egg yolk-based extender

• Published in: Cryobiology Vol. 71; no. 2; pp. 329 - 333
• Main Authors: Alcay, Selim, Berk Toker, M., Gokce, Elif, Ustuner, Burcu, Tekin Onder, N., Sagirkaya, Hakan, Nur, Zekariya, Kemal Soylu, M.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-10-2015
• Subjects: Acrosome - drug effects; Animals; Cell Membrane - drug effects; Cryopreservation; Cryopreservation - methods; Cryoprotective Agents - pharmacology; DNA - genetics; Egg yolk; Egg Yolk - metabolism; Freeze Drying; Freezing; Humans; In Situ Nick-End Labeling; Lyophilization; Male; Ram semen; Semen - drug effects; Semen - physiology; Semen Preservation - methods; Sheep - physiology; Sperm Motility - drug effects; Spermatozoa - drug effects; Egg yolk; Ram semen; Lyophilization; Cryopreservation
• ISSN: 0011-2240; 1090-2392
• DOI: 10.1016/j.cryobiol.2015.08.008

•Lyophilization of egg yolk extender for ram semen cryopreservation.•Semen collection and cryopreservation in non-breeding season.•Comparison of lyophilized egg yolk extender to fresh egg yolk extender.•DNA fragmentation, defected acrosome and plasma membrane integrity were evaluated.•Lyophilized egg yolk extender can be successfully used for ram semen cryopreservation.
The aim of this study was to evaluate the effects of lyophilized egg yolk extender on ram semen cryopreservation. Ejaculates with a thick consistency, rapid wave motion (3–5 on a 0–5 scale) and >75% initial motility were pooled. Sperm were diluted to final concentration of 1/5 (semen/extender) in lyophilized egg yolk or fresh egg yolk extenders using two-step dilution method. The equilibrated semen was frozen in 0.25mL straws. Semen samples were assessed for sperm motility, plasma membrane functional integrity using hypoosmotic swelling test (HOST), damaged acrosome using FITC-Pisum sativum agglutinin (PSA-FITC) and DNA integrity using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) at three time points: after dilution with extender A, equilibration and post-thaw. The results showed that freezing and thawing procedures (dilution, equilibration and thawing) had negative effects on motility (P<0.001), plasma membrane integrity (P<0.001), acrosome integrity (P<0.001) and DNA integrity (P<0.001). In the study, there were no significant differences between lyophilized and fresh egg yolk extenders when comparing motility, plasma membrane integrity, acrosome integrity and DNA integrity between groups. In conclusion, lyophilized egg yolk extender provided similar cryoprotective effects with fresh egg yolk extender to cryopreserve ram semen.