The first calf cloned and delivered at the University of California, Davis, died Saturday, just three days after its birth. Results of the necropsy or animal autopsy, which should pinpoint the cause of death, are pending.
"We're saddened and disappointed by the death of the calf, " said animal science professor Gary Anderson, an authority on embryonic development in mammals and lead researcher on the cloning study. "And yet the birth itself is a milestone," said Anderson. "We're hopeful that the continued research will help us improve the cloning technique so that it can be useful in animal agriculture, ultimately for producing more healthful meat and milk products."
The brown and white Hereford calf was delivered by Caesarean section Aug. 15 at the UC Davis Veterinary Medical Teaching Hospital. It was part of a research project conducted by Anderson and doctoral candidate Cynthia Batchelder. Their ongoing research is aimed at determining if the type of cell used in the cloning procedure affects cloning success.
The UC Davis calf was cloned from a skin cell taken from the ear of a 15-year-old reddish brown Hereford cow. The calf was carried by a white-faced black surrogate mother, which is a cross between a Hereford and an Angus, both beef breeds.
"I'm awed that we could produce a live calf from an adult skin cell, yet humbled by the knowledge that there were things wrong with her that the best and most advanced medical care available could not overcome," said Batchelder. "On one hand, we in the scientific community have learned so much and on the other hand there is still so much we have yet to understand."
Like many cloned calves and sheep, the UC Davis calf was larger than typical Hereford calves. Although well-proportioned, it weighed roughly 150 pounds compared with the 75-80 pounds usually seen in calves of this breed. As expected, the cloned calf had the same coloring and markings as the Hereford cow from which she was cloned.
A clone is a genetic replica of another living being. Some scientists are studying cloning in hopes that it can be used in agriculture to produce many copies of animals that have valuable qualities -- such as cows whose milk is more nutritious or better for processing dairy foods. Cloning also could be used to genetically engineer cows and sheep that can produce pharmaceuticals in their milk.
It's been estimated that more than 100 cloned calves have been born from fewer than 10 laboratories worldwide. In the United States, calves have been cloned at Texas A&M, University of Wisconsin, University of Tennessee, University of Connecticut and at several private companies.
The current technology used to produce clones in the laboratory is called nuclear transfer because it is based on moving the nucleus of one cell into another cell. The nucleus -- the center part of the cell that contains its DNA -- is withdrawn from an egg cell of one animal. Then a cell is taken from the skin or other tissue of a donor animal of the same species and placed next to the "empty" egg.
An electrical charge is then applied, causing the two cells to fuse together. This transfers all of the genetic information that controls cellular development from the nucleus of the donor cell to the fused egg and triggers cell division to begin. The fused egg is placed in a lab dish with the appropriate nutrients. Eventually, the resulting embryo -- which is a genetic copy of the animal that donated the nucleus -- is transplanted into a surrogate mother.
The cloning research will continue at UC Davis with a half-dozen other cows now in the very early stages of pregnancy with cloned embryos. Calves resulting from those pregnancies would be born in early spring.
Materials provided by University Of California - Davis. Note: Content may be edited for style and length.
Cite This Page: