Preventing Horn Growth in Dairy Cows Through Genome Editing

Scientists from UC Davis recently published their paper evaluating the use of genome editing to prevent dairy bulls from growing horns.  Cooperative Extension specialist at UC Davis and corresponding author of the research article, Alison Van Eenennaam noted that the project has been an interesting implementation of genetic modification.  The intended result of the research is to ultimately improve the health and welfare of dairy cows. 

“Farmers would like to have polled animals, but at the moment the elite sires that are genetic superstars of the dairy industry also carry horns,” said Van Eenennaam.  “Horns are a problem for human workers and for herd mates in terms of the damage that animals can do with the horns.”

Using genome editing to prevent horn growth presents an alternative to current methods of addressing the issue, in which horns are burned off calves at a young age.  The absence of horns is a naturally occurring genetic variant, or allele, which is seen in other cattle breeds such as Angus.  The report shows that bringing the hornless allele into the genome of a dairy bull can produce healthy offspring that do not grow horns.

“We’ve been working with some bulls that were produced by a Minnesota based company called Recombinetics, who used genome editing to introduce the characteristic of not growing horns into a dairy bull,” Van Eenennaam noted.  “Those bulls passed that trait onto their offspring and all six of the offspring that were produced by that bull also didn’t grow horns.”

The research was published in the journal Nature Biotechnology and all the data has been shared with the U.S. Food and Drug Administration.  There are still challenges that will need to be overcome before genome-edited bulls are allowed to enter the food supply chain, as regulations dictating genome-edited animals remain complicated.  The recent research shows promise for the future of dairy cow genetics in the event that regulatory obstacles are addressed.

“The animal it was introduced to here was never intended for commercialization, it was not a particularly genetic superior animal,” said Van Eenennaam.  “If this was going to move forward to industry, you would want to introduce that characteristic into elite dairy genetics.”