title: Production of lambs of predetermined sex after the insemination of ewes with low numbers of frozen-thawed sorted X- or Y-chromosome-bearing spermatozoa.
abstract: The fertilizing ability of sex-sorted frozen-thawed ram spermatozoa was assessed after insemination of mature Merino ewes at a synchronized oestrus. Ewes were inseminated into the uterus or utero-tubal junction (UTJ) with a total of 140 x 10(6) unsorted (control) or 2-4 x 10(6) sorted (X or Y) frozen-thawed ram spermatozoa 54 to 57 hours after removal of progestagen-impregnated pessaries and an injection of 400 IU of pregnant mare serum gonadotrophin (Folligon, Intervet). The spermatozoa were separated into X- and Y-chromosome-bearing spermatozoa after analysis with a modified high-speed cell sorter (SX MoFlo). The number of ewes pregnant after insemination with unsorted frozen-thawed spermatozoa was significantly higher (26/48; 54.3%) than for ewes inseminated with either X- (12/48; 25.0%) or Y-sorted spermatozoa (7/48; 14.6%) (P<0.05). Seventeen of the eighteen lambs produced by ewes inseminated with X-sorted spermatozoa were female (94.4%) and 8/8 lambs from ewes inseminated with Y-sorted spermatozoa were male (100%). The sex ratio of the lambs born to ewes inseminated with sex-sorted spermatozoa was significantly skewed from the 51.3% male and 48.7% female ratio in the control group (P<0.05). This study showed, for the first time, that lambs of predicted sex can be produced after insemination with low numbers of sex-sorted cryopreserved ram spermatozoa.
authors.affiliation: Centre for Advanced Technologies in Animal Genetics and Reproduction, Faculty of Veterinary Science, The University of Sydney, NSW 2006, Australia. fionah@vetsci.usyd.edu.au
authors.forename: F K
authors.initials: FK
authors.lastname: Hollinshead
authors.forename: J K
authors.initials: JK
authors.lastname: O'Brien
authors.forename: W M C
authors.initials: WM
authors.lastname: Maxwell
authors.forename: G
authors.initials: G
authors.lastname: Evans
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology; D000177:Acrosome / Q000648:ultrastructure; D000818:Animals; D001724:Birth Weight; D002469:Cell Separation; D015925:Cryopreservation / Q000662:veterinary; D005260:Female; D006064:Gonadotropins, Equine / Q000008:administration & dosage; D006358:Hot Temperature; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D008297:Male; D011247:Pregnancy; D011372:Progestins / Q000008:administration & dosage; D012662:Semen Preservation / Q000662:veterinary*; D012743:Sex Preselection / Q000662:veterinary*; D012744:Sex Ratio; D012756:Sheep; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure*; D014960:X Chromosome; D014998:Y Chromosome
chemical_list: D006064:Gonadotropins, Equine; D011372:Progestins