TOKYO (AP) -- A cloned cow gave birth to a calf conceived by artificial insemination at a research center in northwestern Japan on Monday, showing that cloned cows can reproduce.
The newborn, a female weighing 58.3 pounds, is the world's first reported example of a calf being born to a cloned cow, said Koichi Yamamoto, deputy director of the Ishikawa Prefectural Center for Animal Husbandry and Research, 190 miles northwest of Tokyo.
"This is very significant in showing a cloned cow can give birth and shows maternal instincts," Yamamoto said. He said the newborn calf, which still doesn't have a name, is healthy and suckling from its mother.
The center in Japan has succeeded in creating five clones, using cells around a cow's ovary. All five clones underwent artificial insemination, and so far two of them have gotten pregnant.
One of them -- Kaga No. 2, born in 1998 -- gave birth Monday. Another, called Nodo No. 2, is expected to give birth in September, Yamamoto said.
He said the new calf isn't a clone but a half-clone.
A clone is made from the genetic material of only one animal, instead of two. To produce a clone, scientists remove the genetic material from an animal's egg and replace it with the nucleus of a cell from the animal to be cloned. The egg is then encouraged to divide in a lab until it becomes an embryo, when it is implanted in the womb of another animal.
Dolly the sheep, the first mammal cloned from an adult cell in 1996, was the first to prove that clones can breed normally and produce healthy offspring. She conceived the natural way and gave birth to Bonnie in 1998, and then triplets in 1999. The scientists who created Dolly in Scotland have detected no defects in her lambs.
"This shows that what is true in sheep is true in cows," said Alan Colman, research director at Edinburgh, Scotland-based PPL Therapeutics, the company that produced Dolly.
The use of artificial insemination in the calf's birth does not mean the cloned cow cannot conceive naturally with a bull in a field, Colman said. He said artificial insemination is a common practice cattle breeders use for convenience and control.
Since Dolly, scientists have produced clones from adult cows, goats, mice and pigs.
Sheep are now being genetically modified to carry human medicines in their milk. Such sheep could be cloned to produce large supplies of medicine.
Japanese researchers are eager to perfect cloning in cows because of the nation's market for expensive high-quality beef.