Whipsnade did breed Musk Oxen.
A pre war plan of the park shows yaks in Dagnall Paddock, the present site of the Cheetah enclosure.
Whipsnade My Africa by Lucy Pendar mentions an unusual export of yak in 1989.
During the USSR's invasion of Afghanistan in 1980 the Kirghiz people, (of Turkish-Mongolian origin) fled to Pakistan. The Turkish government consider anyone who speaks Turkish to belong to their country and organised a relief programme. The Kirghizis were transported to an area near Mount Ararat and allowed to settle there. When asked what it was that they missed most of all from their previous existance they replied yaks.
ZSL were contacted as they had the best breeding record with yaks in the world and 1.2 were donated to the Kirghiz people. The male was deemed not healthy enough to be exported but the two cows were sent abroad.