title: Successful low dose insemination of flow cytometrically sorted ram spermatozoa in sheep.
abstract: The fertility of ram spermatozoa that had undergone flow cytometric sorting (MoFlo SX) and cryopreservation was assessed after low-dose insemination of synchronized Merino ewes. Oestrus was synchronized with progestagen-impregnated pessaries, PMSG and GnRH treatment. Ewes (n = 360) were inseminated with 1 x 10(6), 5 x 10(6) or 15 x 10(6) motile sorted frozen-thawed (S(1), S(5), or S(15) respectively) or non-sorted frozen-thawed (C(1), C(5) or C(15) respectively) spermatozoa from three rams. An additional group of ewes were inseminated with 50 x 10(6) motile non-sorted frozen-thawed spermatozoa (C(50)) to provide a commercial dose control. The percentage of ewes lambing after insemination was similar for C(50) (24/38, 63.2%), C(15) (37/54, 68.5%), S(15) (38/57, 66.7%), S(5) (37/56, 66.1%) and S(1) (32/52, 61.5%) groups (p > 0.05), but lower for C(5) (19/48, 39.6%) and C(1) (19/55, 34.5%) treatments (p < 0.05). This study demonstrates sorted ram spermatozoa are equally fertile to non-sorted spermatozoa even when inseminated at 2% of the dose. Furthermore, at very low artificial insemination doses (1 or 5 million motile) the fertility of sorted ram spermatozoa is superior to non-sorted spermatozoa inseminated in equal numbers. These results have significance for the future commercialization of sex-preselection technology in sheep as a reduction in the minimum effective sperm number will allow a corresponding decrease in the associated cost per dose.
authors.affiliation: Centre for Advanced Technologies in Animal Genetics and Reproduction (ReproGen), Faculty of Veterinary Science, The University of Sydney, Sydney, NSW, 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: J A
authors.initials: JA
authors.lastname: Downing
authors.forename: J K
authors.initials: JK
authors.lastname: O'Brien
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D004973:Estrus Synchronization / Q000502:physiology; 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*; D012756:Sheep / Q000502:physiology*; D013076:Sperm Count / Q000662:veterinary; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000502:physiology*