title: Effects of final dilution rate, sperm concentration and times for cooling and glycerol equilibration on post-thaw characteristics of canine spermatozoa.
abstract: This study re-evaluated a protocol for cryopreservation of canine semen. Semen from 4 beagle dogs was pooled, concentrated by centrifugation and adjusted to increasing sperm concentrations by adding back seminal plasma. The prepared or original semen was diluted with an extender (Egg yolk-Tris-citrate-glucose) and cooled to 4 degrees C (cooling), followed by a second dilution with the same extender including glycerol, equilibrated at 4 degrees C (equilibration), then stored in liquid nitrogen. The semen was diluted for frozen samples having a fixed sperm concentration with increasing dilution rates or for those having the reverse combinations. Various dilution rates of 2.5-10 folds or sperm concentrations of 0.25-2.5 x 10(8)/ml had no significant effect on post-thaw sperm characteristics. When cooling was done for different times (0-26 hr) with glycerol equilibration for 1 hr, post-thaw characteristics were better at 2 and 3 hr of cooling, while various times for equilibration (0-4 hr) with cooling for 3 hr had no effect. These results suggest that different dilution rates and sperm concentrations within the ranges tested may not affect the post-thaw sperm characterisitics and that sufficient time for cooling may be essential but a specific equilibration time may not necessarily be required.
authors.affiliation: The United Graduate School of Veterinary Sciences, Gifu University, Japan.
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Okano
authors.forename: Tetsuma
authors.initials: T
authors.lastname: Murase
authors.forename: Makoto
authors.initials: M
authors.lastname: Asano
authors.forename: Toshio
authors.initials: T
authors.lastname: Tsubota
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods*; D004285:Dogs / Q000502:physiology*; D008297:Male; D012662:Semen Preservation / Q000379:methods*; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors