Applications of embryo transfer and related technologies to cattle.

It is possible to recover embryos from superovulated cows nonsurgically, divide each embryo in half, and routinely obtain pregnancy rates of greater than 50% per half embryo after nonsurgical transfer, which is equivalent to greater than 100% per original embryo. It is also possible to freeze and sex embryos, although the cryopreservation process kills some embryos and the sexing process is so new that efficacy under field conditions is unknown. Embryo transfer techniques are applied to thousands of dairy cows, but in 1982 only about one dairy calf per thousand born in North America was from embryo transfer. Nevertheless, use of this technology is increasing, in part because of simplification of procedures, increased efficacy, and lower costs. It is difficult to predict when additional technologies will become available for commercial use, but it is likely that several additional exciting developments will occur in cattle breeding before the end of the century.