Grasping the bull by the horns could soon be a distant memory for British dairy farmers after scientists genetically engineered male animals to rid them of their dangerous prongs.
Dairy cattle 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, Davis, 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 simply 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 major success which 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 corresponding author Dr Alison Van Eenennaam, with the UC Davis Department of Animal Science.
“We've demonstrated that healthy hornless calves with only the intended edit can be produced.
“They were not noticeably more aggressive – although must admit I would not go in the pen woth any of them as they weigh around a ton and can be dangerous with or without horns!”
Horned cattle are major headache for British farms because they cause significant risks for handlers, other stock, or members of the public. Only a few breeds, such as the Hereford and Angus do not have horns.
Around five people are killed in accidents each year, with 74 fatal attacks since 2,000 according to the Health and Safety Executive (HSE).
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.
Scientists did not observe any other unintended genomic alterations in the calves, and all animals remained healthy during the study period.
They also showed no behavioural alterations. Some animals, such as elephants can become more aggressive when their horns are removed, but because the bulls never had horns, they do not miss them.
However regulators have not yet agreed whether animals produced through genetic engineering should be allowed into the food line. So the experimental cows produced by the University of California cannot yet be used in farming either in the US or the UK and neither the bull, nor the calves, have entered the food supply.
Boris Johnson, the Prime Minister, recently said he wanted to take advantage of genetic editing to improve farming in Britain, and leaving the EU would release the UK from regulations on genetically modified organisms (GMOs).
“In a perfect world it would be possible to introduce this edit into the next generation of elite dairy bulls which are used for artificial insemination as that is a way to rapidly disseminate this trait,” added Dr Van Eenennaam.
“ However this will depend upon how the regulations work. At the current time the US FDA considers this animals containing intentional alterations to be new animal drugs, and hence they need to be approved before entering commerce.
“Other countries are not treating them differently to conventionally bred animals (e.g. Argentina). And Europe seems likely to consider all genome edits to be “GMOs”.
Despite the regulatory hurdles, the breakthrough was welcomed by farmers.
NFU chief science and regulatory affairs adviser, Dr Helen Ferrier, 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 environment.
“Techniques such as genome editing are an extension of the genetic improvement through breeding that farmers have done since the birth of modern agriculture.”
The University of California team is also hoping to perfect a technique to genetically design cattle so that they only produce male offspring, which grow faster than females.
The scientists are also hoping to engineer cows which are less prone to pneumonia, which would reduce their need for antibiotics.
The research was published in the Nature Biotechnology.