title: Pregnancy rates of mares inseminated with semen cooled for 18 hours and then frozen.
abstract: The ability to ship cooled stallion sperm for subsequent freezing at a facility specializing in cryopreservation would be beneficial to the equine industry. Stallion sperm has been centrifuged, cooled to 5 degrees C for 12 h, and frozen without a detrimental effect on motility in a previous study; however, no fertility data were available. Experiment 1 compared the post-thaw motility of sperm cooled for 18 h at 15 or 5 degrees C at either 400 or 200 x 10(6) sperm/mL and then frozen. Storage temperature, sperm concentration, or the interaction of temperature and concentration had no effect on total (TM) and progressive motility (PM) after cooling. Post-thaw TM and PM were higher for control than (P < 0.05) for treated samples. There was no difference in post-thaw TM and PM due to temperature or concentration. Experiment 2 further evaluated procedures for cooling before freezing. Ejaculates were either cooled to 5 degrees C for 18 h and centrifuged, centrifuged at room temperature and then cooled to 5 degrees C for 18 h before freezing, or centrifuged and frozen immediately (control). There was no difference among treatments on post-thaw TM or PM. In Exp. 3, mares were inseminated with semen that had been extended in skim milk-egg yolk without glycerol, centrifuged, resuspended at 200 x 10(6) sperm/mL, cooled to 5 degrees C for 18 h, and then frozen or not cooled for 18 h before freezing (control). Pregnancy rates did not differ for mares receiving semen cooled and then frozen (21 of 30, 70%) or semen frozen directly without prior cooling (16 of 30, 53%). In summary, a procedure was developed for cooling stallion sperm for 18 h before freezing without a resultant decrease in fertility.
authors.affiliation: Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins 80523, USA.
authors.forename: T
authors.initials: T
authors.lastname: Backman
authors.forename: J E
authors.initials: JE
authors.lastname: Bruemmer
authors.forename: J K
authors.initials: JK
authors.lastname: Graham
authors.forename: E L
authors.initials: EL
authors.lastname: Squires
mesh_terms: D000818:Animals; D002498:Centrifugation; D003080:Cold Temperature; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary; D005260:Female; D005298:Fertility / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*; D013997:Time Factors