Sex determination in bisected bovine embryos and conception rate after the transfer of female demi-embryos

Abstract

The aim of this study was to evaluate the efficiency of sex determination after microsurgical splitting of D7 (Day 7) bovine embryos and to test the conception rate after subsequent transfer of female demi-embryos. High-quality morulae (n = 100) and early blastocysts (n = 123) obtained from superovulated donors were microsurgically bisected and blastomeres biopsied from one half of bisected embryos were analysed by PCR using specific primers for the Y-chromosome determinant. The female demi-embryos were transferred (ET) in pairs (bilateral) or individually (ipsilateral) to synchronized recipients. Sex determination was successfully completed in 92% of morulae (42.4% female) and 89.4% of early blastocysts (43.6% female). Conception rates were 56.5% (30.4% identical twins) and 48.8% (19.5% identical twins) after bilateral (n = 46) and ipsilateral (n = 82) transfers, respectively. The number of foetuses in relation to the number of original embryos before splitting was 40/46 (87%) and 40/41 (97.6%) after bilateral and ipsilateral transfers of demi-embryos, respectively. The results document that the microsurgical bisection in combination with PCR sex analysis represents a rapid and reliable approach to increase an amount of sex-desired calves in embryo transfer programs.

Keywords

• cattle
• embryo
• superovulation
• splitting
• sexing
• polymerase chain reaction
• embryo transfer