It’s an exciting new twist, but it isn’t the end of sex.
The science that gave birth to Dolly, a sheep cloned from the genetic material of an adult sheep, will give livestock breeders a potential new way to create top-performing animals, but it is no threat to traditional livestock breeding, say people in the cattle industry.
“This isn’t genetic improvement, it’s genetic status quo,” said Brian Shea, a geneticist at Alta Genetics, a Calgary company that analyzes and sells bull semen.
“You’re never going to replace sexual reproduction. You have to have a crossing between the male and female lines to have improvements.”
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Shea said Dolly is a stunning scientific breakthrough because no one has ever before cloned an animal from adult animal tissue. Previously, animals could be cloned from very early embryos, before the cells had become “differentiated,” or specialized.
Dolly’s DNA came from a cell in an adult ewe’s mammaries.
The Scottish experiment proves DNA in an egg can be scraped out and replaced with the complete DNA of an adult, so the resulting animal will be an exact genetic duplicate of the original.
When Alta Genetics was cloning embryos, Shea said the precise nature of the animal couldn’t be foretold, because two sets of DNA, from mother and father, were mixed.
“If you had good genetics (on both sides), then we’d have to assume it would be good,” he said. “Now you can just simply identify the best producing animals and make copies of them.”
Alta Genetics got out of cloning because it was not cost-effective.
Shea said cloning could be particularly useful in areas such as the dairy industry, in which certain characteristics are especially valuable.
“If you’ve got a cow that produces 20,000 kilos of milk per year, you’d like to have some copies of her,” he said. “You wouldn’t mind having a barn full like her.”
But while specific high performing animals might be cloned, Shea said there probably never will be even one percent of livestock produced through cloning.
Duncan Porteous of the Canadian Hereford Association said he was glad to hear news of Dolly, because the science that created her could help increase the number of animals with good genes, but he said there will never be a day when every Hereford is the same.
Ideal for environment
“There is no such thing as an ideal Hereford,” said Porteous. “They have to be raised under such a variety of circumstances.”
Porteous said he thinks hogs and dairy cattle might be better beneficiaries of cloning, since they live in controlled environments and need widely applicable qualities.
“Cows are an industry that takes wasteland and turns it into red meat production,” Porteous said. “If you could produce these in a Petri dish and have them live there, then maybe it would work, but they need to live under different environments and management conditions.”
Beef cattle producers have different feed supplies, environments, grazing lands and financial resources so each will need to build his own customized herd, he said.
Shea said genetic advancements may seem abstract to producers, but concrete benefits of DNA research may soon be seen by livestock breeders.
He said Alta Genetics is slowly finding out how to spot specific, high performance genes in bull semen, and as it discovers more, producers will get a better idea of what they can expect with each shot.
“It’ll take a lot of the mystery out of what we’re getting when we purchase one of these things.”
