Dehorning cattle has become a cause celebre among animal rights activists in recent years. In an exclusive interview, Bruce Jobson reports on a ground-breaking scientific technique known as gene editing which could result in 100% polled animals being bred in the near future.
The animal welfare lobby has raised concerns regarding the disbudding and dehorning of cattle and the stress levels which are involved.
However, the University of California Davis (UC Davis) has developed a gene-editing technique which could save millions of pounds in veterinarian costs and farm labour.
Two calves at the UC Davis campus will never grow horns, instead the two animals have soft hair on their crowns where horn mounds would normally emerge. And, more importantly, their offspring should also lack horns should the technique be proven accurate.
The scientific breakthrough resulted in the calves being designed in a petri-dish at Minnesota based Recombinetics, according to Alison Van Eenennaam who is a geneticist at UC Davis’ College of Agriculture and Environmental Sciences, which has worked in association with the Minnesota lab.
Five years ago, Scott Fahrenkrug, then a molecular geneticist at the University of Minnesota, and the present owner of Recombinetics, considered ways to eliminate the problem of dehorning. He investigated the DNA sequence of Angus cattle, a breed which is naturally polled, and used a genetic-editing method known as TALENs in order to introduce a sequence into skin cells of a horned Holstein bull.
In total, Farenkrug deleted 10 DNA letters and replaced 212 letters into the sequence. Some of the cells were then turned into embryos through cloning technology, and subsequently used to impregnate donor cows, and the resulting calves were born at UC Davis.
The process is a first-ofa- kind result called genetic editing and is effectively an experimental test run which is expected to massively impact the beef and dairy industry as well as the entire food chain, according to Ms Van Eenennaam.
The project is also part of a larger research programme targeted at how to make cattle easier to manage, rear and transport.
In an exclusive interview with Dairy Farmer, Alison Van Eenennaam emphasised the technique was ‘precision breeding’ and similar to ‘word processing’ as an analogy, in order to describe the differences between genetic editing and genetic engineering. She considers genetic editing to change the spelling of a word within a document while genetic engineering is similar to pasting in a word from a completely different document.
“You’re not bringing in something foreign which is what is associated with genetic engineering,” she explains. “With the two dairy calves, a precise section of DNA responsible for horn growth was knocked out and replaced with a precise section from a cow that does not produce that trait. Many cattle varieties do not grow horns, including Angus cattle.”
With dairy cattle – both male and female have horns – and the resulting progeny are dehorned soon after birth. Current polled bloodlines are limited and use of genetic editing will bring greater breed diversity and lead to extended use of the technique.
UC Davis will, in turn, collect semen from the two bull calves, named Spotigy and Buri, to inseminate into horned cows.
The aim is to monitor the calves’ growth and development and see whether the two bulls accurately transmit the hornless trait to their offspring. The odds are 100% if Mendelian genetics holds true, and if successful it will allow the AI industry to bypass decades of breeding for polled, or hornless, cows. Gene editing technology could eventually revolutionise the beef and dairy industry.
One of two calves which will never grow horns – instead the animals have soft hair on their crowns where horn buds would normally emerge.
Another animal geneticist at UC Davis, Pablo Juan Ross, has been trying to perfect a technique originally developed a decade ago, but now gaining more acceptance, to design cattle that produce only male off-spring. Male calves grow faster than females and therefore, in beef production herds, males are more desirable.
But perhaps one of the most fascinating consequences of genetic editing could help breed cattle that are less prone to pneumonia, which in turn, would reduce the need for antibiotics which is another current challenge.
Australian-born Ms Van Eenennaam remains positive about developing the process of genetic editing. She believes it can be a positive good for animal health and welfare as well as an advantage in the food supply chain.
Indeed, scientists at Washington State University have already identified a gene edit which makes cattle less susceptible to respiratory disease.
Some of the above mentioned animals involved in the respiratory work carry the edited gene in utero and are scheduled to be shipped to UC Davis in 2016, although the university has not as yet received the funding to continue the research.
The potential for reducing respiratory disease could have widespread global implications in terms of vet bills and labour costs, as well as impacting on efficiency and farm profitability.
Figures show that an estimated 16% of cattle in US feedlots show signs of respiratory disease at some point during their feeding regime, and USDA data demonstrates nearly onethird of all cattle deaths are due to respiratory issues which costs US producers $643 million (£460m) on an annual basis.
According to Ms Van Eenennaam, a staggering 20% of the world’s animal protein is being lost because of disease.