XY sperm separation and use in artificial insemination and other ARTs.

Many tens of thousands of calves resulting from artificial insemination (AI) have been born worldwide after XY sperm separation and commercial production is underway in several countries. Accuracy of sex selection is some 90% and can be achieved both in research facilities and at AI studs in rural locations. Most facilities sort X- sperm which have also be utilised for superovulation and embryo transfer projects and for in vitro fertilisation (IVF) as well as AI. Sort rates of some 15 x 10(6) sperm/h are currently achievable and are used for low dose insemination, generally at 2 x 10(6) frozen sperm per dose, at a minimum of 35% post thaw motility. Pregnancy rates are some 70% to 80% of normal "high" dose unsexed inseminates. Good herd management is essential for high pregnancy rates with sexed sperm. In addition to cattle, offspring of predetermined sex have been born in the human, sheep, pig, horse, rabbit, elk, buffalo, cat and dolphin. Each species has its own challenge with regard to sperm handling and insemination procedure. In pigs, horses and sheep, the available dose of sexed sperm is very considerably lower than that which is used for conventional AI and special approaches have been devised for each species. In the pig a flexible catheter has been used to deliver a small dose of semen as close to the site of ovulation as possible. In the horse, hysteroscopic insemination at the utero tubal junction has resulted in fertilisation and, in the sheep, laparoscopic insemination into the uterus is the standard procedure for both sexed and unsexed sperm. Further advances in the efficiency of sorting together with improvements in sperm handling should result in acceptable pregnancy rates in these species.