The University of California, Davis Department of Animal Science recently acquired two Holstein bull calves that are genetically polled as a result of gene-editing techniques. Researchers at the university plan to raise the calves to maturity and mate them to multiple Holstein cows to measure the effects of the gene-edited trait on their progeny.
Gene editing is a relatively new application of molecular biology with potential for rapidly introducing a new or modified genetic trait in animals. News reports recently described how researchers at the University of Missouri have used gene editing to produce a line of pigs that are resistant to Porcine Reproductive and Respiratory Syndrome (PRRS).
The gene-edited calves, named Spotigy and Buri, were bred by Recombinetics, a genetic technology company in Minnesota.
Most lines of Holsteins need to be mechanically dehorned to prevent injuries to diary workers and other cows, a process that increases labor costs and creates concerns over animal health and welfare. Breeders have produced some lines of genetically polled Holsteins using conventional breeding methods, but horned lines make up the vast majority of cattle in U.S. dairies.
UC-Davis geneticist Alison Van Eenennaam, PhD, is managing the project. Quoted in an article in the Sacramento Bee, she compares gene editing to changing the spelling of a word in a word-processing document, while genetic engineering would compare with pasting in a new word copied from a different document.
In genetic engineering, scientists can introduce genetic material from a different species into a cell’s DNA to produce a new genetic trait. In gene editing, scientists can rearrange a precise section of DNA, or remove it and replace it with a section of DNA from the same species, but coded for a different expression of the genes, such as polled versus horned. This technology potentially can allow breeders to change or alter a single trait, while leaving the rest of the organism’s genome unchanged.
In producing Spotigy and Buri, scientists removed a section of DNA coded for horn growth and replaced it with another coded for the polled trait.
Van Eenennaam believes gene editing has potential to significantly improve animal health and productivity, resulting in reduced resource use and improved sustainability in food production.