Reengineering Life
Scientists Gene Edited a Cow to Have Mostly Male Offspring
The technique could eventually lead to fewer cattle needed to produce the same amount of beef
Reengineering Life is a series from OneZero about the astonishing ways genetic technology is changing humanity and the world around us.
On a sunny Tuesday in April, amid a global pandemic, a newborn calf took his first shaky steps in a barn outside Sacramento. Animal geneticist Alison Van Eenennaam and postdoctoral researcher Joey Owen, looked on in awe. This wasn’t just any bull calf. This animal had been gene edited so that he could eventually produce more male offspring than normal.
The bull calf, affectionately named Cosmo, was the result of five years of research. Nine months earlier, Van Eenennaam, Owen, and a team of seven other scientists used the gene-editing tool CRISPR to insert a gene into cow embryos, including the embryo that eventually became Cosmo. The gene, SRY, is responsible for male sex development in cattle, and adding it to a female essentially swaps its sex. The researchers’ goal was to make a bull that would father mostly boys.
“The idea was actually suggested to me by a cattle operation,” Van Eenennaam, PhD, a researcher at the…
