Impact of cloning on cattle breeding systems.

The concept of clone-family testing is compared with existing progeny testing systems. The critical factors that will decide how cloning is utilized are the potential size of cloned families, and the cost per embryo (or per calf born). If family sizes of 100,000 become routinely achievable (cheaply), then clone testing becomes viable. In rough figures, cloned embryos costing $30 with a 50% calving rate would be attractive to farmers and would be cheap enough that farmers would buy more (crossbred) embryos in order to breed further replacement cows. At $300 per embryo, farmers would be more inclined to buy a number of cloned pure-bred female embryos and then to use conventional artificial insemination to breed further replacements from these superior cows. At $3000 per embryo, farmers would probably only be interested in very small numbers of cloned animals, most of which would be males. The relative importance of adult versus fetal cloning is discussed. The need for gene banks to preserve genetic variation is emphasized; both gametes and somatic tissue cultures should be considered.