Meet Cosmo, a Bull Calf Genetically Designed to Produce 75% Male Offspring!

Scientists Use CRISPR Technology to Insert Sex-Determining Gene.Scientists at the University of California, Davis, have successfully produced a bull calf, named Cosmo, who was genome-edited as an embryo so that he’ll produce more male offspring. The research was presented in a poster yesterday, (July 23, 2020) at the American Society of Animal Science meeting.



Using the genome-editing technology CRISPR, researchers can make targeted cuts to the genome or insert useful genes, which is called a gene knock-in.  In this case, scientists successfully inserted or knocked-in the cattle SRY gene, the gene that is responsible for initiating male development, into a bovine embryo. It’s the first demonstration of a targeted gene knock-in for large sequences of DNA via embryo-mediated genome editing in cattle.


More males, more beef!

Van Eenennaam says part of the motivation to produce more male cattle is that male cattle are about 15 percent more efficient at converting feed into weight gain. They are more fuel-efficient than females. Additionally, they tend to be processed at a heavier weight.

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