What do you call a baby donkey?

Sunday saw our first 2008 visit to the local children's farm park. H still regards most of the residents with suspicion, but on this occasion one new arrival met with a certain degree of approval. Esme the donkey had foaled just days before; the staff were eager to name him. I asked H what he would call the young colt.

"Donk!" he replied despairingly, as if I was the only person on the planet that didn't know.