Wagyu steak is widely known amongst food enthusiasts for its perfect marbling, buttery flavor, and soft, tender texture. But what goes into making Wagyu in particular so special? And how do breeders ensure that the cattle they breed eventually become the melt-in-your mouth steak cuts served on the platter?

A new Wagyu genome discovery by a team of scientists at the University of Adelaide in partnership with the USDA was able to uncover an entire X chromosome (one of the sex chromosomes) of Wagyu cattle for the first time, as well as four complete autosomes (non-sex chromosomes). Using a cutting edge method, the team constructed the most complete cattle genome available, 16% longer than the previous reference cattle genome. The newly available chromosomes, titled UOA_Wagyu_1, provide the most comprehensive tool breeders have ever had for Wagyu cattle.

This method is known as haplotype-resolved assembly , which involves reconstructing chromosomes based on the parental chromosome sets in an organism's DNA. Unlike traditional processes, this one allows for an allele-specific genome analysis, which gives insight into how the different parental alleles (versions of the same gene) are expressed in the individual. It also gives more information on genetic variations and structural differences, which influence genetic diversity within a species.

The discovery of the complete X chromosome is particularly notable, especially when it comes to breeding the perfect Wagyu cattle. Previously, no completely sequenced X chromosome was available, though it was known to carry genes involved in mental functions, intellectual disabilities, reproduction, and milk production in cattle. With the new cattle X chromosome, the genes expressing these characteristics can be better understood, allowing breeders to make more informed decisions with regard to their cattle.

Within the cattle X chromosome, the team also discovered a new neocentromere . Centromeres are regions of the chromosome that play roles in cell division. Neocentromeres occur when centromeres are found in unexpected areas of the chromosome,which is rare to discover. These neocentromeres can even hint towards evolution , as their presence implies that the species' genome is undergoing new developments. The genes in these neocentromeres were also found to be expressed in the testes, meaning they likely play a role in cattle reproduction, another important factor to be aware of for breeders.

Various other discoveries of the Wagyu genome were made, including 738 new protein coding genes and 2,397 new structural genetic variants, and which only provide a more complete picture on how Wagyu cattle become the delicious Wagyu steak that so many enjoy.

While most rarely consider the decisions that go into making their favorite steak so appetizing, breeders value detailed genetic information, allowing them to make the best decisions when it comes to their cattle. With this new discovery, breeders now have the most complete resource ever available, so that next time you order a Wagyu steak, it is served with that characteristic marbling and flavor that makes it so enjoyable.