Scientists in China say they have produced cloned cattle with increased resistance to bovine tuberculosis.
Twenty calves were born, of which 11 survived for more than three months.
Bovine TB is a risk to cattle in many countries, including parts of the UK, Africa and Asia.
Researchers in China used a genome editing tool to change the genetic code of cattle. They say the technology could have widespread uses in agriculture.
A team from the College of Veterinary Medicine, Northwest A&F University in Shaanxi, China, altered a gene involved in fighting infection.
"The resulting transgenic cattle exhibited increased resistance to M. bovis (bovine TB) infection," they said.
"Our study provides an avenue to develop the CRISPR/Cas9 system for agricultural applications."
Scientists in China have previously inserted a mouse gene into cattle in an attempt to boost protection against TB.
The latest research, published in the journal, Genome Biology, used the new genome editing tool, which is more precise.
Tests on resistance to TB were carried out on blood samples taken from the cloned animals.
It is not clear what would happen if the transgenic cattle were exposed to tuberculosis in normal conditions.
Prof Ian McConnell, emeritus professor of veterinary science at the University of Cambridge, said TB in cattle is a complex disease.
"Although it is a thorough and novel paper on using gene technology in transgenic cattle at this stage I doubt if the research will have any application to prevention of TB in cattle using transgenic technology," he said.
And Prof Alan Archibald, head of genetics and genomics at The Roslin Institute, University of Edinburgh, added: "I was not convinced that the authors had demonstrated that the edited calves were resistant - there was no pathology reported for the edited or control animals."
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