Embryo production from superovulated sheep inseminated with sex-sorted ram spermatozoa

An experiment was undertaken to assess the fertilizing capacity of sex-sorted, frozen-thawed ram spermatozoa, artificially inseminated into superovulated ewes, and the quality and survivability of the resultant pre-sexed embryos. Synchronized (intravaginal progestagen pessary and GnRH) donors were superovulated using PMSG and repeat ovarian stimulation with FSH before insemination. Ewes (n = 67) were inseminated with either 30 x 106 or 15 x 106 motile non-sorted (control) or 15 X 106 motile sex-sorted (sorted) frozen-thawed spermatozoa (control: C-30 or C-15; sorted: S-15, respectively) and the resultant embryos transfer-red immediately into synchronized recipients (n = 160). The percentage of transferable embryos, pregnancy rate and embryo survival were similar (P > 0.05) across all treatments. Oocyte cleavage rate was higher for ewes inseminated with S-15 (172/ 230; 74.8%; P < 0.05) than for C-15 (97/151; 64.2%) or C-30 (89/141; 63.1 %) spermatozoa. Of the lambs resulting from embryos produced with sex-sorted spermatozoa, 86/93 (92.5%) were born of the predicted sex. This study demonstrated for the first time that pre-sexed offspring derived from superovulated sheep can be produced following transfer of embryos. Furthermore, sex-sorting by flow cytometry did not compromise the in vivo fertilizing capacity of ram spermatozoa in superovulated sheep, nor did it affect the quality or survivability of the resultant embryos. (c) 2006 Elsevier Inc. All rights reserved.