The impact of cloning disease-resistant cattle is potentially monumental

Prof Joe Templeton, Texas A&M University

The month-old Angus calf named 86 Squared is a copy of an animal that had a natural resistance to three infectious diseases - brucellosis, tuberculosis and salmonellosis - all of which can be passed on to humans through uncooked beef, unpasteurised milk or contamination.

If resistance can indeed be copied into livestock, it offers the promise of herds of disease-free cattle, the scientists claimed.

"The impact of cloning disease-resistant cattle is potentially monumental," said Joe Templeton, a professor of genetics and veterinary pathobiology at Texas A&M University. "This research will benefit ranchers in many countries who cannot afford to vaccinate or test their herds.''

Valuable animals

The new clone is also an interesting development because it was produced using cells that had been frozen for 15 years. This is thought to be the longest-preserved genetic material ever used in a successful cloning experiment.

The experiment has implications for the use of growth promoters in animal feed

The Texas scientists said this could open up new possibilities for cloning animals which died many years ago, but for which cells had been preserved. "Who knows how many people have genetic material from extremely valuable animals that might now be cloned?'' said co-researcher Dr Mark Westhusin.

The cloning of 86 Squared was done at the same Texas A&M facility where last year scientists produced a calf from the cells of a 21-year-old bull, the oldest animal ever cloned.

They also are working on the $2.3 million Missyplicity Project, funded by a California couple to clone their deceased dog. Westhusin said the dog had not yet been reproduced because dogs were proving difficult to clone.

Anitbiotic resistance

Commenting on the production of 86 Squared, Steven Kappes, an animal germ plasma and reproduction expert with the US Agriculture Department's research service, said: "What they've done is identify an animal that appears to have resistance to these diseases and all they're doing is making another animal that's genetically identical to it.''

Missy: The dog is playing hard to get for the cloners

He went on: "So they're not making the animal safer to eat. What they're doing is just making more of something that is good. That is a key: to identify animals that are genetically superior in certain traits and this allows us to make more of them.''

Professor Templeton said clones like 86 Squared could address concerns about the widespread use of antibiotics in livestock feed. The inclusion of these therapeutic agents helps to keep animals disease-free, and has the added benefit of promoting growth - animals get fatter, quicker because they do not waste energy fighting illness.

But there are worries that this approach may compromise food safety and human health by accelerating the emergence of antibiotic-resistant pathogens.

Professor Templeton said science could design clones that did not need these growth promoters.

"You just turn them loose, let them eat the grass and enjoy,'' he said. "When they go into the food market, they don't have antibiotics in them.''

The "parent" of 86 Squared, which died three years ago, was called simply Bull 86. In 1985, cells from the tip of Bull 86's ear were frozen for future genetic study.