LAUSR

Abstr Act : The aim of this study was to evaluate the effect of sex determination procedures in Day 7 to Day 8 bovine embryos of various quality. For the purposes of comparison we used high quality (HQ) as well as lower quality (LQ) embryos obtained from superovulated donors. The healthy embryonic cells isolated from HQ embryos and blastomeres protruding into the perivitelline space of LQ embryos, were analysed by polymerase chain reactions (PCR) using primers specific for the Y chromosome determinant. After microsurgical intervention and comple - tion of sex determination, the female embryos were then transferred (ET) to synchronized recipients. A total of 310 embryos of HQ were used and gender was safely determined in 275 cases (88.7%). PCR analysis of extruded cells isolated from 170 LQ embryos was carried out with certainty only in 111 embryos (65.3%, P < 0.01). After ET of 122 HQ sex defined embryos, pregnancy was established in 69 recipients (56.6%). A similar conception rate 51.9% (27/52) was found after the ET of sex defined embryos designated as LQ. The accuracy of analysis was confirmed after calving and revealed that designated female sex coincided with 95.5% and 96.2% of calves when HQ and LQ embryos were transferred, respectively. Our results clearly show that a microsurgical technique in combination with PCR method represents a rapid and reliable approach for sex determination in HQ as well as in LQ preimplantation bovine embryos and can be used in field conditions for the regulation of the sex of progeny in selected herds.