Scientists in China have developed cloned cattle which they say are more resistant to tuberculosis. The scientists used the relatively new CRISPR technique in their research.

Bovine TB is one of the major threats facing the cattle industry in the UK; 28,000 cattle were slaughtered under TB restrictions in 2015 and the disease is estimated to cost the public purse around £100 million a year. bTB also affects parts of Asia and Africa.

Researchers from China’s Northwest A&F University used a genome editing tool to confer greater resistance to the disease to 11 cows. They tested resistance using blood samples taken from the cloned animals.

However, Professor Alan Archibald, Head of Genetics and Genomics at The Roslin Institute, University of Edinburgh, said he wasn’t convinced that this meant the cloned cows would be resistant to TB themselves.

Prof Archibald said, “The authors had shown some evidence of differences in response to infection, but views on the interpretation of some of the assays differ.

“Tb is a problem in the UK dairy sector and is controlled in the UK by culling.  Animals that show positive skin tests are culled; the skin test provides some evidence that the animal has been infected, so cattle that are genome edited to be tolerant would be just as likely to be culled. Susceptibility to Tb is now included in genomic breeding values in the UK following research at Roslin.”

Also commenting on the study, Ian McConnell, Emeritus Professor of Veterinary Science at the University of Cambridge, agreed with Prof. Archibald that the paper didn’t demonstrate that cattle would be resistant to TB in real-life scenarios. Prof. McConnell said, “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.”

The scientists in China used a new CRISPR method that sliced through only one strand of DNA to insert their new gene. Previous methods that sliced through both strands of DNA could lead to unwanted mutations occurring when cells repaired themselves, however, the scientists said there was no evidence of this in their experiment.

The CRISPR technique makes genetic modification a cheaper and simpler process, but cloning of farm animals has been banned in the EU over animal welfare concerns. Although commercial cloning is relatively widespread in other global regions - notably the United States, South America and China - the mortality rate of cloned animals is high and cloned animals are often sickly; many of those born alive die quickly, and in painful ways.