In April 2020, a team of scientists at the University of California, Davis, made a calf named Cosmo more likely to produce male offspring, according tomedia New Atlas. The team made adjustments using the CRISPR gene editing tool, in which case a gene called SRY was inserted. This gene initiates male development, making the animal’s own offspring more likely to be male.
Ideally, the SRY gene would be inserted into the X chromosome — so that Cosmo produces 100% of the male offspring. But the team couldn’t do that, so they chose chromosome 17 instead. As a result, about 75% of males were converted to males by converting chromosomes that would normally be female. As an additional bonus, chromosome 17 is a safe harbor location, so insertion does not destroy adjacent genes.
“We expect cosmo’s offspring to be male if they inherit the SRY gene, whether or not they inherit the Y chromosome,” said study author Alison Van Eenennaam.
So why do researchers prioritize bulls? Apparently this is a digital game for the beef industry – bulls are up to 15% efficient at converting feed into weight. In the end, each cow gets more meat at a lower cost. There are also some environmental benefits, as producing the same amount of beef requires fewer cattle.
Of course, the effect of the whole thing will have to wait a while to know. Cosmo will not reach sexual maturity for a year. And because the FDA has strict rules on CRISPR editing food, Cosmo and its offspring will not enter the food supply. It’s more about testing whether this gene editing works.
For now, CRISPR has been used in the past to edit various animals for various purposes. Scientists have designed pigs to fight swine flu or lower body fat, lizards to algetynos, mosquitoes to be mosquitoes that can’t spread disease, or mice to experiment with new ways to treat the disease.
The study was presented at the American Society for Animal Science meeting.