Slow cooling prevents cold-induced damage to sperm motility and acrosomal integrity in the black-footed ferret (Mustela nigripes).
The endangered black-footed ferret (Mustela nigripes) has benefited from artificial insemination; however, improved sperm cryopreservation protocols are still needed. The present study focused on identifying factors influencing gamete survival during processing before cryopreservation, including: (1) the presence or absence of seminal plasma; (2) temperature (25 degrees C v. 37 degrees C); (3) type of medium (Ham's F10 medium v. TEST yolk buffer [TYB]); (4) cooling rate (slow, rapid and ultra-rapid); and (5) the presence or absence of glycerol. Seminal plasma did not compromise (P > 0.05) sperm motility or acrosomal integrity. Sperm motility traits were maintained longer (P < 0.05) at 25 degrees C than at 37 degrees C in Ham's or TYB, but temperature did not affect (P > 0.05) acrosomal integrity. Overall, TYB maintained optimal (P < 0.05) sperm motility compared with Ham's medium, but Ham's medium maintained more (P < 0.05) intact acrosomes than TYB. Slow cooling (0.2 degrees C min(-1)) was optimal (P < 0.05) compared to rapid cooling (1 degrees C min(-1)), and ultra-rapid cooling (9 degrees C min(-1)) was found to be highly detrimental (P < 0.05). Results obtained in TYB with 0% or 4% glycerol were comparable (P > 0.05), indicating that 4% glycerol was non-toxic to ferret sperm; however, glycerol failed to ameliorate the detrimental effects of either rapid or ultra-rapid cooling. The results of the present study demonstrate that the damage observed to black-footed ferret spermatozoa is derived largely from the rate of cooling.
Santymire
R M
RM
Department of Reproductive Sciences, Conservation & Research Centre, Smithsonian's National Zoological Park, Front Royal, VA 22630, USA. rsantymire@lpzoo.org
Marinari
P E
PE
Kreeger
J S
JS
Wildt
D E
DE
Howard
J G
JG
D000177:Acrosome / Q000502:physiology*; D000818:Animals; D003080:Cold Temperature; D003247:Conservation of Natural Resources; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents; D005289:Ferrets / Q000502:physiology*; D005947:Glucose; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D012661:Semen / Q000502:physiology; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility / Q000502:physiology*; D014325:Tromethamine
D003451:Cryoprotective Agents; C077847:TES-Tris yolk buffer; D014325:Tromethamine; D005947:Glucose