Freezing equine semen: the effect of combinations of semen extenders and glycerol on post-thaw motility.
OBJECTIVE
We evaluated combinations of two commercial semen extenders and three concentrations of glycerol to determine the combination that yielded the highest post-thaw sperm motility.


METHODS
A randomised 2 x 3 block design was used.


METHODS
Semen was collected from four stallions (6 collections per stallion). The sample was diluted with either a dried skim-milk glucose extender (EZ Mixin Original Formula) or a chemically defined, milk-free diluent (INRA 96), and each was used in combination with 2%, 3% or 4% glycerol in standard commercial freezing medium. Sperm motility was assessed by microscopy in fresh and post-thaw semen.


RESULTS
There was a significant difference between the two extenders in the motility of spermatozoa after cryopreservation (48.9% for INRA 96; 38.6% for EZ Mixin OF; P < 0.0001). Glycerol at 4% in freezing medium yielded the highest post-thaw motility, significantly better than 2% (P < 0.05). Three of four stallions had significantly higher post-thaw motility using INRA 96 relative to EZ Mixin OF (P < 0.01), and two of four stallions had significantly higher post-thaw motility using 4% glycerol (P < 0.05). The combination of INRA 96 and 4% glycerol in freezing medium gave the highest average post-thaw motility of 51.5%.


CONCLUSIONS
In this study, INRA 96 combined with 4% glycerol yielded an average recovery of progressively motile sperm consistently above the 35% target.
Scherzer
J
J
College of Veterinary Medicine, University of Georgia, Athens, GA, USA. jakobs@uga.edu
Fayrer-Hosken
R A
RA
Aceves
M
M
Hurley
D J
DJ
Ray
L E
LE
Jones
L
L
Heusner
G L
GL
D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D005990:Glycerol / Q000494:pharmacology*; D006736:Horses / Q000502:physiology*; D008297:Male; D011897:Random Allocation; D012661:Semen / Q000502:physiology*; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility / Q000502:physiology
D003451:Cryoprotective Agents; D005990:Glycerol