After a year of trying, [Australian geneticist Alison Van Eenennaam’s lab at the University of California succeeded in using] the gene-editing tool CRISPR to add a gene called SRY to some bovine skin cells. And SRY is no ordinary bit of DNA. All on its own, the presence of SRY can make a female turn out to be essentially male—with bigger muscles, a penis, and testicles (although unable to make sperm).
Gene-editing technology has big potential in farm animals. It has been used to create pigs immune to viruses and sheep whose wool grows longer. Van Eenennaam participated in a successful effort to edit dairy cows to eliminate their horns.
Now, in the project she calls “Boys Only,” she aims to create a bull that will father only male offspring: either normal bull calves or ones with two X chromosomes but also the male-making SRY. No females at all.
That would be valuable to beef ranchers, she thinks, because males grow bigger and faster. It’s that much more steak. Beef is already America’s most valuable farm product. Imagine, she says, CRISPR bulls roaming the pastureland, skewing the odds toward maleness and making the industry more efficient.
Read full, original post: Meet the Woman Using CRISPR to Breed All-Male “Terminator Cattle”