No, it doesn't look right for a Desert Bighorn Sheep. The horns are too thick at the base, the color is not quite right, and there is a bit extra fur on the neck that O. c. nelsoni does not have.
Hmmm... trying to match up the exhibit with anything Tomek may have visited on the same trip. O. v. bochariensis at Liberec, possibly?
(Just to unnecesssarily muddy the waters, Prague (and Arnhem's) bighorns are 'officially' californiae, which is considered the same as nelsoni now, but not historically)
I apologise for the entire confusion. This pictures is showing the male of Bukhara Urial (Ovis bochariensis) from the Liberec Zoo. Through the hurry I put this pictures in the Terarium Prague gallery.