Back to the Biblical word "ass" for a moment (okay, so I'm anal-retentive): here's a site explaining the different ways in which the word is used in the Bible, and the different words from which the English word "ass" was translated. The verse from Deuteronomy is listed under the original word "Chamor", meaning "the male ass", so obviously the authors weren't talking about a sterile mule.

Holman Bible Dictionary -- Ass

Unfortunately, I can't find the same sort of dissection of the word "ox" on that site.

Anyway, according to frogprince's earlier post of 12 Dec 06 - 10:55 PM, I guess I should be trying to look up "world" or "earth" on that site.