title: Birth of offspring of pre-determined sex after artificial insemination of frozen-thawed, sex-sorted and re-frozen-thawed ram spermatozoa.
abstract: The fertility of ram spermatozoa cryopreserved prior to, and following, sex-sorting by flow cytometry was assessed after insemination of mature Merino ewes at a synchronised estrus. Ewes were inseminated with spermatozoa from three rams, split into four treatment groups: 50 x 10(6) motile non-sorted, frozen-thawed (Control50), 15 x 10(6) motile non-sorted, frozen-thawed (Control15), 15 x 10(6) motile sex-sorted, frozen-thawed (SF15) or 15 x 10(6) motile frozen-thawed, sex-sorted, re-frozen-thawed (FSF15) ram spermatozoa. Separation of SF15 and FSF15 treatments into X- and Y-chromosome-bearing populations was achieved using a high-speed sperm sorter. The percentage of ewes lambing after insemination was similar for Control15 (36/74; 48.6%), SF15 (35/76; 46.1%) and FSF15 (26/72; 36.1%) groups (P>0.05). A higher percentage of ewes produced lambs in the Control50 (38/70; 54.3%) than the FSF15 group (P<0.05). Fifty-one of the 55 (92.7%) lambs derived from fresh, sex-sorted frozen-thawed spermatozoa were of the predicted sex, as were 41/43 (95.3%) lambs derived from frozen-thawed, sex-sorted, re-frozen-thawed spermatozoa. This study demonstrated for the first time in any species that frozen-thawed spermatozoa, after sex-sorting and a second cryopreservation step, are capable of producing offspring of the predicted sex following artificial insemination.
authors.affiliation: Centre for Advanced Technologies in Animal Genetics and Reproduction (ReproGen), Faculty of Veterinary Science, The University of Sydney, Sydney, NSW 2006, Australia. simong@vetsci.usyd.edu.au
authors.forename: S P
authors.initials: SP
authors.lastname: de Graaf
authors.forename: G
authors.initials: G
authors.lastname: Evans
authors.forename: W M C
authors.initials: WM
authors.lastname: Maxwell
authors.forename: D G
authors.initials: DG
authors.lastname: Cran
authors.forename: J K
authors.initials: JK
authors.lastname: O'Brien
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D007315:Insemination, Artificial / Q000662:veterinary*; D008297:Male; D011247:Pregnancy; D018873:Pregnancy Rate; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D012743:Sex Preselection / Q000379:methods / Q000662:veterinary*; D012756:Sheep / Q000502:physiology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology*