title: Bull semen in vitro fertility after cryopreservation using egg yolk LDL: a comparison with Optidyl, a commercial egg yolk extender.
abstract: Low-density lipoproteins (LDL) have been previously isolated and identified as the cryoprotective fraction of yolk. The effect of LDL on sperm motility after freezing-thawing has been reported, but no study has been made to assess the effect of LDL on bull semen fertility. The aim of this study was to evaluate the fertility of bull semen cryopreserved in the presence of LDL. Motility of semen cryopreserved in LDL was analyzed and compared to semen cryopreserved with Optidyl, a commercial extender containing egg yolk. To evaluate the fertilizing ability of semen, we used in vitro fertilization test, whereas acrosome and plasma membrane integrity were also evaluated. The percentage of motile spermatozoa was two fold higher after freezing in LDL than in Optidyl 54.4% versus 30.2% (P < 0.05). The cleavage rate was significantly higher after fertilization with semen frozen in LDL than with Optidyl 63.0% versus 54.8% (P < 0.05). No significant difference was observed on the blastocyst rate after in vitro culture. Integrity of the acrosome and the plasma membrane were maintained in both extenders. In conclusion, LDL preserve bull semen quality and fertilizing ability, allowing also better semen motility, after the freeze-thaw process.
authors.affiliation: Laboratory of Biotechnology and Pathology of Reproduction, National Veterinary School of Nantes, Nantes, France.
authors.forename: Lamia
authors.initials: L
authors.lastname: Amirat
authors.forename: Daniel
authors.initials: D
authors.lastname: Tainturier
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Jeanneau
authors.forename: Chantal
authors.initials: C
authors.lastname: Thorin
authors.forename: Olivier
authors.initials: O
authors.lastname: Gérard
authors.forename: Jean Luc
authors.initials: JL
authors.lastname: Courtens
authors.forename: Marc
authors.initials: M
authors.lastname: Anton
mesh_terms: D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle; D002462:Cell Membrane / Q000648:ultrastructure; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents; D046508:Culture Techniques; D004530:Egg Yolk / Q000737:chemistry*; D005307:Fertilization in Vitro / Q000662:veterinary; D008077:Lipoproteins, LDL; D008297:Male; D012661:Semen / Q000502:physiology; D012662:Semen Preservation / Q000662:veterinary*; D013081:Sperm Motility; D013094:Spermatozoa / Q000648:ultrastructure
chemical_list: D003451:Cryoprotective Agents; D008077:Lipoproteins, LDL