title: Semen characteristics of genetically identical quadruplet bulls.
abstract: Modern cloning methods have become an important technology in artificial insemination which is used to create and maintain pools of genetically superior bull semen. In this study, semen from four identical quadruplet bulls (Q(1), Q(2), Q(3), and Q(4)) produced by blastomere separation was analyzed to evaluate the differences in reproductive potential, if any, that existed between the identical quadruplet siblings. Analysis of fresh semen collected from 1994 to 1996, showed lower progressive motility and lower sperm concentration for one bull (Q(3)) compared to his identical brothers (P<0.05). Semen characteristics following freezing-thawing procedures have also been tested for these quadruplet bulls. The percentage of motility, progressive motility, and mean path velocity were lower in Q(4) compared with Q(1). Moreover, intracellular calcium level and P25b level (P25b is a sperm surface protein proposed to be a potential bull fertility marker) were lower in Q(4) compared with his siblings (P<0.05). Cryodamage to Q(4)'s frozen-thawed spermatozoa were confirmed by a lower percentage of embryo development after in vitro fertilization. Thus, the higher instability of cryopreserved spermatozoa from Q(4) and the lower semen production of Q(3), compared to their siblings, indicate that differences in semen characteristics can indeed exist among genetically identical animals produced by blastomere separation.
authors.affiliation: Département d'Obstétrique-Gynécologie, Faculté de Médecine, Université Laval, Sainte-Foy, Que., Canada G1K 7P4.
authors.forename: Carl
authors.initials: C
authors.lastname: Lessard
authors.forename: Isabelle
authors.initials: I
authors.lastname: Masseau
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Bilodeau
authors.forename: Tom
authors.initials: T
authors.lastname: Kroetsch
authors.forename: Hermenegilde
authors.initials: H
authors.lastname: Twagiramungu
authors.forename: Janice L
authors.initials: JL
authors.lastname: Bailey
authors.forename: Pierre
authors.initials: P
authors.lastname: Leclerc
authors.forename: Robert
authors.initials: R
authors.lastname: Sullivan
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D002417:Cattle / Q000235:genetics*; D019976:Cloning, Organism; D015925:Cryopreservation / Q000662:veterinary; D005314:Embryonic and Fetal Development / Q000235:genetics; D005298:Fertility / Q000235:genetics; D005307:Fertilization in Vitro / Q000662:veterinary; D014644:Genetic Variation; D006358:Hot Temperature; D008297:Male; D012661:Semen / Q000166:cytology*; D013076:Sperm Count; D013081:Sperm Motility / Q000235:genetics; D013094:Spermatozoa / Q000737:chemistry / Q000502:physiology*
chemical_list: D002118:Calcium