The University of California, Davis' Alison Van Eenennaam is using CRISPR to develop all-male cattle, Technology Review reports.

Her goal, it adds, is to develop bulls that will only sire male offspring in a project she's dubbed "Boys Only." That, Van Eenennaam says, would help beef ranchers out as males are bigger and grow faster and would make the industry more efficient.

She and her lab are going about it by inserting the SRY gene, which is usually found on the Y chromosome, on the X chromosome, Tech Review says. In mammals, that gene, also called testis-determining factor, can make an animal physically male, even without a Y chromosome, it adds.

So far, Tech Review reports that Van Eenennaam and her team have been able to add SRY to an X chromosome in male skin cells, and that they next have to tackle doing that in a cattle embryo or cloning that altered skin cell. Any males made in this way are expected to be sterile, it notes.

Van Eenennaam has previously worked on developing hornless dairy cows by splicing a gene from Angus cattle, which naturally lack horns, into dairy-producing Holsteins.