Bulls have their horns ‘edited out’ in advance for genetic engineering
‘Hornless’ Aberdeen Angus gene spliced into dairy herds, but animals remain banned from food chain
GRASPING the bull by the horns could soon be a distant memory for British dairy farmers after scientists genetically engineered male cattle to rid them of their dangerous prongs.
Dairy breeds typically grow horns, which can injure farm workers, ramblers and dog walkers, so they are usually removed when the calf is young, in a process known as “debudding”.
As well as making the animal safer, dehorning also makes it easier to pack bulls into pens and trucks because horns take up space, but the process is extremely painful for the animal.
Now scientists at the University of California have successfully bred hornless bulls after splicing the “hornless” gene from Aberdeen Angus cattle into the widespread black-and-white Holstein dairy cows so that they are born without protrusions. Instead they grow soft hair on the parts of their heads where hard mounds normally emerge.
Two years on from the first genetically engineered calves, researchers have confirmed that their offspring also do not have horns, a success that could allow the farming industry to bypass decades of selective breeding.
“Gene-editing is a technology that can seamlessly combine the desired traits of two unrelated animals without crossbreeding, thus preserving the present-day production from dairy cattle while eliminating horns with genetic methods,” said author Alison Van Eenennaam, of the UC Davis Department of Animal Science.
“We’ve demonstrated that healthy hornless calves with only the intended edit can be produced.”
Analysis by the US Food and Drug Administration (FDA) showed the fragment of DNA used to introduce the hornless trail had successfully integrated into the offspring, meaning their calves should also lack horns.
No unintended genomic alterations were observed in the calves.
However regulators have not yet agreed whether animals produced through genetic engineering should be allowed into the food chain.
The University of California team hopes to perfect a technique to genetically design cattle to produce only male offspring, which grow faster than females. The scientists also hope to engineer animals that are less prone to pneumonia.
Dr Helen Ferrier, the NFU chief science and regulatory affairs adviser, said: “The NFU sees technological developments such as genome editing as positive for our industry, given the opportunities they present for genetic improvements that can benefit animal welfare, farm performance, society and the environment.”
The research was published in the journal Nature Biotechnology.