Clones From Aged Cows Have Normal Pregnancies and Calving
(Released: 06/ /01)
By David Bauman, Office of University Communications
STORRS, Conn. -- Researchers at the University of Connecticut
announced today (June 5) that a Holstein heifer named "Daisy", cloned two
years ago from an aged
cow, has given normal birth to a 90-pound male calf.
The calf named "Norm," was born at the UConn Kellog Dairy Center
at 9 a.m. on Sunday, June 3, said Dr. Xiangzhong (Jerry) Yang, head
Transgenic Animal Facility. "Daisy gave birth without any assistance,"
Yang said. "Both the Mom and calf are doing fine."
Scientists have previously reported on cloned cows giving normal
births in Japan, but these clones were made from young donor cows or
What makes Norm's birth special, researchers say, is that Daisy
was cloned from an aged animal (passed menopause). The fact that Daisy
can reproduce normally
demonstrates that the cloning process can reverse the physiological
age process, similar to conventional reproduction.
Ever since researchers in Scotland electrified the world by cloning
"Dolly" the sheep, scientists were concerned that cloned animals might
reflecting the age of the DNA of the animals from which they were
cloned. Recently, Yang's team reported in the journal Nature
Genetics that all clones have
normal cells with regard to telomeres (lengths of DNA on the ends
of chromosomes), and are indistinguishable from calves produced
reproduction. Their results showed that cloned calves do not have
cells that are unnaturally old and do not inherit the cellular
genetic age of their donor. Similar
results have been found in cattle by the Worcester, Mass.-based
company Advanced Cell Technology, and in mice by the Rockefeller
"Although it might be anticipated that clones from aged animals may
have normal reproductive capacity as those cloned from young animals,
the normal birth of
'Norm' and several other normal pregnancies from aged clones here at
UConn provides evidence that when you clone from an aged individual,
you do not get an
aged copy," Yang said.
Despite other reported problems associated with cloning, including
high rates of abortion and neonatal death, Yang said research has
shown that cloned animals,
once they have passed the first few critical days after birth, can
live and reproduce like conventionally reproduced animals. Yang notes
that his UConn research
team and their Japanese collaborators have produced several dozen
clones from adult cattle, male and female. Almost all the surviving
clones appear as normal
as other calves.
"These findings are significant because of their important medical
implications," added Yang. He suggested that Norm's successful birth
moves science a bit
closer to the promise of "Therapeutic cloning," in which human's own
cells would be harvested for tissues that could treat diseases such
as diabetes or
"Therapeutic cloning is aimed to convert skin cells or other
somatic (body) cells from diseased individuals to embryonic stem
cells, which may then be
differentiated into any needed cell or tissue types for therapy,"
Yang said. "Obviously demonstration that clones from aged animals
can develop and reproduce
normally is important, because when therapeutic cloning is eventually
applicable to human therapy, older individuals are likely to be the
intended beneficiaries for
This implies that
when cells are harvested from old individuals for therapeutic
cloning one can expect that these cells can be converted to fresh
young cells as
those from young individuals," he said.
"Norm's birth is also significant for agriculture and saving
endangered species," Yang added. "Proven valuable animals are
desired to be cloned and normal
reproductions of the clones are of course desired."
Daisy was cloned from a 13-year-old high-merit cow named "Aspen,"
and was born at UConn on July 7, 1999.
Daisy is the fourth live-clone produced at UConn. Her other
sister - the now famous "Amy" - was born on June10, 1999,
becoming the first clone of an adult
large animal in North America. A total of 10 clones have been
produced from Aspen, the aged cow, including Amy, Betty, Cathy
and Daisy, who are still alive.
Betty and Cathy are also pregnant and due to calve soon.
Aspen, who also is still alive, is now nearly 15 years old and
has long passed her calf-bearing age. Aspen had a high milking
record, producing approximately
35,000 pounds of milk per year. It is yet to be determined whether
her clones will have the same high milk production ability.
June 2001 Releases