Cloned Cattle Can Be Healthy and Normal

The possibility of cloning humans has raised questions as to whether nuclear transfer can be used to reproducibly generate healthy adult animals. Reports in the popular and scientific press on genetic, immunological, and other developmental problems raise the question of whether there are “any normal clones in existence ” (1–4). We evaluated a series of 24 sexually mature cattle, cloned from nonquiescent somatic cells as described (5, 6). A total of 496 blastocysts were transferred into progestin-synchronized recipients, and 110 of the 247 recipients (45%) were preg-nant as determined by ultrasound 35 to 40