Jan. 6, 2003 COLLEGE STATION – They behaved just like pigs. Or at least, that's what a study of cloned pigs found at Texas A&M University.
The behavior of cloned pigs, produced last year at Texas A&M, were compared to pigs bred normally. The recent study was completed by master's of science student Greg Archer, under the supervision of Dr. Ted Friend, professor of applied ethology in the department of animal science.
"We found the variation within a litter of clones to be as variable or greater (than the normal litters) at least 80 percent of the time for all the tests that we did," Archer said.
In other words, they were pretty much regular litters of pigs, he said.
Two litters of cloned pigs were compared to two litters of "control" pigs in tests that measured the variation in food preference, temperament and how pigs spend their time. Archer also compared their weight, shoulder width, nose to tail length, growth rate and other physical characteristics.
What Archer found was the cloned pigs’ behavior was just as variable as the control group of pigs in just about every way. They played, ate, slept, fought and responded to outside stimuli with the same range of behavior as the others. Even their physical characteristics – compared using body measurements and blood serum tests – were similar to the control group in variation. And that means there was variation between the cloned pigs.
"A litter of pigs is just as variable as another litter of pigs. They're not more uniform," he said.
Even though the cloned pigs may be exact genetic replicas of the parent, it's believed variations can come from the environment and epigenetic factors, causing the DNA "line up" differently, he said. Epigenetic phenomena is defined as any gene-regulating activity that doesn't involve changes to the DNA code and that persists through one or more generations, he said. That may explain why abnormalities such as fetal death occur in cloned species, he added.
"When cells start dividing, sometimes the DNA changes the way it lines up. So, even though the pigs have the same genetic type, it might not be lined up in the same order," he said.
Archer said that's throwing some doubt on the theory that if a pet, or any animal, is cloned, its progeny will be exact duplicates. "You're not going to get your exact pet," Archer said.
"You're going to get one close to it, but it's not going to be exact."
Friend said even though animals are not exact duplicates, “All of the other potential uses for cloned animals is still there, waiting to be further developed and tested. We did not know what type of behavioral variability would be found until this study was completed.”
Other potential uses of cloning are organ transplants to humans, production of drugs, and improvement of certain characteristics of livestock, Friend said.
Archer, a native of Baltimore, Md., received his bachelor's degree in animal science from Virginia Tech University.
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