If you have a multiple pasture rotation, you won't have any issues. The poo breaks down very quickly and is great fertilizer and since waterfowl and equines have different parasite issues, there is no worm contamination from one to the other. (My vet told me that.)
Some donkeys have very fine fur and some have coarse. Actually, the coarse is a bigger pain to keep clean because dirt easily rinses from the fine haired donkeys, but the coarse tends to hang onto the grunge.
I've never had alpacas. I bet they are beautiful in the pasture. You'll love your geese and ducks too. They are so much fun to watch.
Some donkeys have very fine fur and some have coarse. Actually, the coarse is a bigger pain to keep clean because dirt easily rinses from the fine haired donkeys, but the coarse tends to hang onto the grunge.

I've never had alpacas. I bet they are beautiful in the pasture. You'll love your geese and ducks too. They are so much fun to watch.