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UConn scientists score a first
with cloned calf
June 21, 1999
research team of animal scientists at UConn June 10 announced the birth of the first cloned calf from an adult farm animal in the United States.
At about 10:30 a.m., a Holstein heifer named Amy, was delivered by C-section at the University's Kellogg Dairy Center, said Xiangzhong "Jerry" Yang, associate professor of animal science and head of the Transgenic Animal Facility.
Amy's birth is especially significant because she is the first successfully cloned animal from non-reproductive related cells, said Yang, noting that the new-born calf was cloned from the ear skin fibroblast cells of an adult cow. With the exception of mice, Amy is the first animal cloned from adult fibroblast cells, Yang said.
Amy's genetic mother, Aspen, is nearly 14 years old. She had 8 births, but produced only one heifer. She is too old to reproduce naturally or by traditional sexual reproduction, said Yang.
"We took a simple ear skin biopsy (a simple, minute-long procedure) and used the cells for cloning," Yang explained. The embryo was then cultured for seven days in the laboratory and transferred to a surrogate mother on October 5. The first clone, Amy, was born June 10, weighing 94 pounds.
"This is the first large animal cloned from genetic material extracted from an adult farm animal in the United States," said Yang. "Dozens of laboratories around the nation have been racing to produce the first clones from adult farm animals, particularly cows. We're happy to be the first one."
Two years ago, the cloned sheep Dolly was produced when scientists inserted a cell from a ewe's udder into an egg after removing the egg's DNA. The bioengineered embryo was implanted in a ewe's womb.
Last summer, the first cloned cows were produced from the oviduct or oocyte cumulus cells.
"The fact that Amy is produced from the skin fibroblast cells is of significance because compared to using female reproductive cells (mammary tissues or reproductive organ cells), skin biopsy may be taken more easily, without using any equipment, and is non-invasive, " Yang explained. "Secondly, skin cells may be taken from either sex of the animal and at any age. This is significant for efforts in saving endangered species."
Amy was cloned from an aged, high-performing cow, said Yang. Aspen is 13 years old and produces 35,000 pounds of milk annually. Cloning adult animals offers the possibility of quickly expanding a valuable herd of high milk-producing cows or genetically engineered animals that are of proven value. Yang said the technology also offers a potential tool to generate or multiply transgenic animals as organ donors or for the production of therapeutic proteins.
"Amy is a very valuable clone from a valuable cow," said Yang, noting how the young heifer's black-white pattern is identical to that of her genetic mother. "We hope that her level of milk production is identical too."
There are still many questions to be answered about cloning. An important question is whether cloning will reprogram the donor's age. Geneticists recently announced that Dolly may be susceptible to disease and premature aging because her genes were copied from a six-year-old sheep.
Yang said UConn scientists will closely follow Amy's lifespan, health, behavior, growth and aging rate, and her own reproductive performance, to monitor the effects of her genetic mother's age.
"Cloned animals are ideal for many research experiments, such as comparing drug efficiency, nutrition tests or toxicology tests," said Yang. "Because the animals are genetically identical, the experimental findings are not confounded by genetic variation factors and the number of animals used for experiments may be reduced significantly."