Influence of extender, temperature, and addition of glycerol on post-thaw sperm parameters in ram semen.
Using a two-step extension methodology, two experiments were conducted using a split-sample design to compare the effect on post-thaw ram sperm parameters of a milk-based extender (Experiment 1) containing four different egg yolk concentrations (5% [M5], 10% [M10], 15% [M15], and 20% [M20]), and a commercially available extender (Bioexcell); IMV, L'Aigle, France) free from additives of animal origin, containing two different final glycerol concentrations (3.2% [B] and 6.4% [BB]) (Experiment 2). In both experiments, glycerol was added either at 5 degrees C or at 15 degrees C together with the second fraction of each extender. The sperm characteristics assessed were motility (measured subjectively [SM] and by means of cell motion analysis (CASA), membrane integrity (SYBR-14/PI), and capacitation status (chlortetracycline (CTC)/EthD-1). Results of Experiment 1 showed no significant positive effect of increasing the concentration of egg yolk above 10% on post-thaw motility, membrane integrity, or induction of sperm capacitation-like changes. In Experiment 2, Bioexcell (BB) yielded similar post-thaw results as did the milk extender (control). In both experiments, post-thaw sperm parameters were better preserved when glycerol was added at 5 degrees C, although the results were not always statistically significant for all variables studied. In conclusion, when using milk-based extenders for freezing ram semen, low (5-10%) concentrations of egg yolk and the addition of glycerol at 5 degrees C are recommended. Furthermore, the results indicate that when freezing ram semen, Bioexcell containing 6.4% glycerol may be used as an alternative extender to the conventional milk extender containing 5% egg yolk.
Gil
Jorge
J
Department of Obstetrics and Gynecology, Faculty of Veterinary Medicine, Swedish University of Agricultural Sciences (SLU), Ullsvägen 14C, Box 7039, Uppsala SE-750 07, Sweden.
Lundeheim
Nils
N
Söderquist
Lennart
L
Rodriíuez-Martínez
Heriberto
H
D020101:Acrosome Reaction / Q000502:physiology; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D004530:Egg Yolk / Q000502:physiology; D005990:Glycerol / Q000494:pharmacology; D008297:Male; D009664:Norway; D010713:Phosphatidylcholines / Q000502:physiology; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D012756:Sheep / Q000502:physiology*; D013075:Sperm Capacitation / Q000502:physiology; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*; D013548:Sweden
D010713:Phosphatidylcholines; D005990:Glycerol