When they talk donkeys they are talking the standard sized jacks not mini's or mediteranian. If you are not used to careing for a horse a donkey is not a good idea. They do work for sheep and goats though I know no one who has them for poultry.
If you are only going to have hens and no roosters I would suggest a Chu Shamo rooster. They are aggressive against other male so will not work in a flock with males. The grow to be 10-12 lbs and tough as all get out. Not good in northern climate without supplemental heat lamp in winter. He...