title: Cryopreservation of bison epididymal sperm: A strategy for improving post-thaw quality when collecting sperm in field conditions.
abstract: This study was conducted to optimize the cryopreservation of epididymal bison sperm harvested in the field. In the first experiment, epididymal bison sperm were treated with or without seminal plasma (n = 6) and cooled to 5 °C over 2 hours. In a separate experiment, glycerol was added at different times and sperm was held at 5 °C for different periods of time before cryopreservation (n = 11). In addition, epididymal sperm frozen with and without seminal plasma (n = 6) and after 4, 24, and 48 hours (n = 5) of equilibration at 5 °C, were evaluated for their in vitro fertilizing ability. Post-thaw motility of bison epididymal sperm was similar when cryopreserved with or without seminal plasma or when glycerol was added at either 0, 4, 24, or 48 hours before freezing (P > 0.05). However, sperm incubated at 5 °C for 24 hours before freezing exhibited higher percentages of motile sperm (44% vs. 35% for 4 hours or 48 hours, P < 0.05). Fertilization rates of bison oocytes were not different for any treatments. Chilling the whole epididymis for 24 or 48 hours resulted in complete loss of sperm viability. In conclusion, bison epididymal sperm can be chilled outside of the epididymis for at least 48 hours before cryopreservation without compromising post-thaw sperm motility providing flexibility for technicians performing field collections.
authors.affiliation: Center of Agricultural Sciences, State University of West Paraná, Cascavel, Paraná, Brazil.
authors.forename: Christiane Garcia
authors.initials: CG
authors.lastname: Vilela
authors.affiliation: Faculty of Animal Science and Food Engineering, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Juliana Messias
authors.initials: JM
authors.lastname: Marquez
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Graham
authors.affiliation: Department of Biomedical Sciences, Colorado State University, Fort Collins, Colorado, USA. Electronic address: Jennifer.Barfield@colostate.edu.
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Barfield
mesh_terms: D000818:Animals; D016164:Bison / Q000502:physiology*; D015925:Cryopreservation / Q000662:veterinary*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D004822:Epididymis / Q000502:physiology*; D005307:Fertilization in Vitro / Q000187:drug effects; D005990:Glycerol / Q000494:pharmacology*; D008297:Male; D012034:Refrigeration / Q000662:veterinary*; D012661:Semen; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary; D013081:Sperm Motility
chemical_list: D003451:Cryoprotective Agents; D005990:Glycerol
keywords: Bison; Chilling; Cryopreservation; Epididymal sperm; Seminal plasma