Translation:One of those twenty-eight animals is a donkey.
Oops... I just reported this as "My answer should be accepted," but it shouldn't. I started to write "the" 28 animals, then decided it should be "those" 28 animals, and forgot to delete "the." SORRY!!!
No need to apologise - I've never been a contributor but I'm pretty much sure that to one correct user-suggested translation there are multiple wrong ones. That's the burden of contributors - to dig through the whole of it and find the few pieces that are right :-)
Since osel is masculine, shouldn't the sentence read 'Jeden...'? Or should it agree with zvíře instead of osel? Just curious...