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5-Animals: Cloned pigs differ from originals in looks and behavior

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TITLE:  Cloned Pigs Differ from Originals in Looks and Behavior
SOURCE: North Carolina State University, USA, Press Release
DATE:   Apr 14, 2003

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Cloned Pigs Differ from Originals in Looks and Behavior

New research at North Carolina State University's College of Veterinary
Medicine indicates that cloned pigs can have the same degree of
variability in physical appearance and behavior as normally bred animals.
Two separate studies show that while clones are genetically identical to
the original animal, the similarities end there.

This dispels the commonly held notion that cloned animals retain the
physical and behavioral attributes of the animal from which they were
cloned. The research was conducted by Dr. Jorge

Overhead comparison of cloned pigs shows hair growth pattern variation.

Piedrahita, professor of molecular biomedical sciences at NC State, and
colleagues at Texas A&M University. His study on cloned pig behavior,
which appears in Applied Animal Behaviour Science, is the first published
research on the behavior of cloned mammals. The study on cloned pig
physiology, which appears in Biology of Reproduction, is the first study
on clone physiology that included control subjects.

Piedrahita says the implications are far-reaching. "The technology of
cloning has been sold to the public as a way of creating a group of
identical animals and, as such, there are companies that have been set up
around this concept, especially for pet cloning. The implication is that
your cloned pet is going to behave and look like the one you already have
- and that will not be the case," he said.

"We demonstrated in our behavioral paper that the behavior of clones is
not identical. They are not homogeneous, so you cannot expect your cloned
pet to behave like your original pet, even discounting environment. We've
cloned animals that were raised in the same environment and they still
didn't act the same," Piedrahita said. In the behavioral study, two
litters of cloned female pigs, consisting of five and four pigs
respectively, and two control litters - each with four purebred pigs -
were used. The purebred control pigs were of the same breed and sex and
were born within the same week as their matched cloned litter. The cloned
pigs were compared with the purebreds on a number of criteria such as
food preferences and temperament.

In the physical study, the pigs were compared using a series of
physiological and genetic parameters. The results indicated that while
cloning creates animals within the normal phenotype - the appearance of
an organism with respect to a group of characters - it increases the
variability associated with some traits. "That means that you can't use
cloned animals to reduce the size of groups involved in animal
experiments," Piedrahita said.

Piedrahita says scientists must be very careful with cloning, since
genetic errors can be introduced into the DNA of the clone during the process.

"Cloning advocates are calling them normal, healthy clones, but we don't
think that is always the case. Some of those animals are going to be
normal and very healthy but others will not. They are healthy enough to
survive but that doesn't make them as healthy as non-cloned animals. At
this point, we just don't have a lot of the answers," he said.

"While clones are genetically identical, physical characteristics such as
size, weight and hair type may not be the same because the DNA has been
modified during the cloning process in such a way that it affects the
activity of certain genes," Piedrahita adds.

Piedrahita believes the behavioral and physiological variables will run
throughout all cloned animals. "Any technology that's being sold that
utilizes the clone itself, not the offspring of the clone, is the one
that you have to be very careful with. That includes applications such as
pet cloning, and the reproduction of high-production dairy cows or
thoroughbred racehorses," he said.

Piedrahita says the benefits of cloning are better realized when the
clone has offspring of its own. That's because any genetic errors are
corrected, meaning that the original animal and the offspring of the
clone will have the same genetic merit.

Piedrahita cites bull breeding as an example. "Say you have a dairy bull
of high genetic merit so that, when mated with any cow, the offspring of
that cow produces more milk. Now, let's say that bull produces very
little sperm and has difficulty producing offspring. You could clone that
animal, and then breed the clones. The offspring of the clones will have
the same genetic merit as the original bull that allows cows to produce
more milk."

"The bottom line is this: While clones are genetically identical,
physical characteristics such as size, weight and hair type may not be
the same because the DNA has been modified during the cloning process in
such a way that it affects the activity of certain genes," he said.

The research was supported by a grant from the National Institutes of Health.

- thomas -

Note to editors: Abstracts of the behavior paper and the physiology paper

"Behavioral variation among cloned pigs"
Authors: Gregory S. Archer and T.H. Friend, Texas A&M University; J.
Piedrahita, North Carolina State University; C.H. Nevill, S. Walker,
Texas A&M University
Published: Feb. 19, 2003, in the early online edition of Applied Animal
Behaviour Science

Abstract: The variability of behavior among cloned animals has yet to be
studied. Through a series of behavior tests, we quantified the variation
in food preference, temperament, and time budgets of two genetically
identical Duroc litters (n=5, 4) and their naturally bred controls (n=4,
4). All litters of pigs were tested for their food preference using
apples, bananas, crackers, and carrots. Variation in temperament was
determined by timing latency to remove a towel (Towel Test) and by
counting vocalizations and escape attempts during Back and Pick-up Tests.
Seventy-two hours of time lapse video were used to determine time budgets
of the pigs consisting of the following behaviors: lying in bedding,
lying on concrete, standing, feeding, and play/fighting. An F-test was
used to determine differences in variation between litter variations. The
clones were similarly or more variable (P<0.05) than the naturally bred
controls: in their preference for the foods in 13 of the 160 comparisons;
in 5 of the 8 comparisons during the Towel Test; in all four comparisons
in the Back and Pick-up Tests; and in 9 of the 10 comparisons in the time
budget analysis. These results reinforce the importance of environmental
effects on animal behavior and question the use of cloning by nuclear
transfer to replicate animals with specific behavioral characteristics.

"Hierarchical Phenotype and Epigenetic Variation in Cloned Swine"
Authors: Greg S. Archer, Scott Dindor, Ted H. Friend, Shawn Walker,
Gretchen Zaunbrecher, Bruce Lawhorn, Texas A&M University; Jorge A.
Piedrahita, North Carolina State University
Published: Accepted by Biology of Reproduction

Abstract: It has been determined that cloning by somatic cell nuclear
transfer can result in the birth of animals with phenotypic and gene
expression abnormalities. We have compared adult clones and adult pigs
from naturally bred control females in using a series of physiological
and genetic parameters including detailed methylation profiles of
selected genomic regions. Phenotypic and genetic analyses indicated that
there are two classes of traits, one where the clones have less variation
than controls, and another characterized by variation that is equally
high in cloned and control pigs. Our results indicate that while cloning
creates animals within the normal phenotypic range, it increases the
variability associated with some traits. This is contrary to the
expectation that one potential use of cloning is to reduce the size of
groups involved in animal experimentation, as well as the use of cloning
to reproduce an animal, including pets, with a homogenous set of desired

Media Contacts:
Dr. Jorge A. Piedrahita, +1-919/515-7407
Greg Thomas, News Services, +1-919/515-3470