Scientists at the University of California at Davis successfully produced a goby named Cosmo, which was genome-edited in embryonic phase so that it could produce more male offspring. The research was presented at a meeting of the American Society for Animal Science, according to the University of California, Davis.

Using CRISPR genome editing technology, researchers can purposefully make changes to the genome or insert useful genes. Scientists call such technologists. “Gene blow”. In this case, scientists have successfully introduced a bovine embryo, or the bovine SRY gene, which is responsible for the development of the male. This is the first demonstration of targeted gene insertion for large DNA sequences through embryo-mediated genome editing in cattle.

Scientists hope that the offspring of the Cosmo goby, who inherit this SRY gene, will grow and look like males, regardless of whether they inherit the Y chromosome.

One of the reasons for producing more male cattle is that the male cattle is about 15% more efficient at converting feed into weight gain. They are more economical to livestock than females.

It can also be important for the environment, scientists say. Far fewer livestock are required to produce the same amount of beef.

The SRY gene was inserted into the bovine chromosome 17. It was selected after failed attempts to insert the gene into the X chromosome, which would result in a bull that only produces male offspring. Cosmo is expected to produce 75% of normal male offspring, 50% of animals with XY chromosomes, and another 25% of XX animals that inherit the SRY gene.

It took two and a half years to develop a method for injecting the gene into the developing embryo, and another two years to successfully complete the pregnancy. But in April 2020, a healthy 110 kg calf was born.

Scientists claim that this is only the beginning of the study. Cosmo will reach puberty in a year and will be bred for study. Is the inheritance of the SRY gene on chromosome 17 enough to trigger the developmental path of males in XX embryos, so that the offspring grow and look like males? It remains to be seen. Since the Food and Drug Administration regulates the editing of animal genes, Cosmo and his offspring will not be fed.