There are 5 dronkeys in Shrek the Third.
When the dronkeys were first introduced in the post-credits scene from Shrek 2, there were 6 in total (3 males and 3 females) including a unique individual named Parfait which was red in color like her mother. She is nowhere to be seen in Shrek the Third.
Originally, only three of the remaining dronkeys were named: Cocoa, Peanut and Bananas. Later on promotional material, the names Chip and Debbie were revealed for the remaining two dronkeys.
http://en.wikipedia.org/wiki/Dronkeys