Embryo production from superovulated cattle following insemination of sexed sperm

Two trials were conducted to ascertain fertilization rate, embryo quality and numbers of transferable embryos in superovulated heifers and cows inseminated with sexed sperm. Inseminates contained 2 × 106, 10 × 106 or 20 × 106 total sperm enriched for the X- or Y-chromosome (∼90%) by flow cytometry/cell sorting. Non-sexed inseminates contained 40 × 106 total sperm. Donors in each trial were allocated to one of each of the bulls included in that study. Each donor was inseminated with frozen/thawed sperm from the same bull for each treatment in successive courses of superstimulation with twice daily i.m. injections of FSH for 4 d. Heifers and cows were inseminated 12 and 24 h after visually observed standing estrus in Trial 1. In Trial 2, a single timed inseminate was used 70–72 h following PGF2α. Ova/embryos were collected non-surgically 7–7.5 d after insemination. In both trials, fewer ova were fertilized with sexed versus non-sexed treatments and with 2 × 106 sexed sperm compared to higher doses (P < 0.05). However, insemination of 20 × 106 total sexed sperm of ≥90% purity resulted in similar numbers of transferable embryos of the desired sex compared to that for non-sexed sperm.