According to the famous Greek physician Hippocrates, donkey milk can be used to cure numerous ailments including poisoning, liver troubles, fevers, and several infectious diseases. This prescription was what led to a donkey milk bathing fad.
Cleopatra was said to have bathed in donkey milk every day. She supposedly needed about 500 donkeys to produce the milk she bathed in daily to preserve her beauty and youthfulness. Cleopatra was not alone in her quest for the perfect skin. Poppaea Sabina, the second wife of Roman Emperor Nero, and Pauline, sister to Napoleon Bonaparte, were also big fans of bathing in donkey milk.
According to the UN’s Food and Agriculture Organization, donkey milk does have some health benefits. In the 20th century, it was used as a substitute for human breast milk because it is more similar in composition than cow’s milk. But since an average donkey only produces about one liter of milk in a day, bathing in the milk is rather wasteful. -- http://listverse.com/