The San Diego Zoo's Frozen Zoo has stored cultured cells from hundreds of species since the 1970s. Cells from a banteng bull that died without leaving descendants were preserved in 1980. In 2003 nuclei from those cells were transferred into enucleated domestic cattle oocytes, and the resulting embryos were carried by domestic cows.
Two calves were produced. One was oversized and was euthanised within days, a known hazard of cloning in cattle. The other was healthy, was raised at San Diego Zoo, and lived for several years before being euthanised after an injury. Its genetic value lay in reintroducing variation from an animal decades dead into a captive population that had lost it.
The result is often reported as a template for reviving lost species, which overstates it. Cloning here required a close living relative to supply eggs and a womb, viable cultured cells rather than degraded ancient DNA, and it produced individuals rather than a population. For the wild banteng, listed as Endangered, hunting and habitat conversion remain the operative problems.