Mmm... unless you got the rooster from a breeder, he's probably an Easter Egger (mutt) rather than an Ameraucana. (If you do a search on this topic, you'll find oodles of explanation as to the difference between Ameraucana, EE and Araucana, just in case you're not familiar with the differences). The fact that he might be an EE is not that much of a big deal, except that you won't know whether he's got two blue egg genes to pass along, or just one... or none--sometimes EEs will lay "pink" (or brownish) eggs rather than blue, and since he's a rooster, there's no way to tell at this point what he ended up with, short of having his DNA tested.
But, say your guy is going to pass on a blue egg gene to brown egg laying hens: probably, that would produce a green or olive egg. The egg would be blue through the shell, but with the brown laid over top, making it look greenish, usually.
If you want a pretty mix of colored eggs including blue, green, brown, pinkish, olive, etc., it can be nice to get EEs from a hatchery. If you get EEs, though, you may not be as sure what you will get when you breed them together later. That's half the fun for some people, though. If you want all blue (or blue-ish) eggs, Ameraucanas and Araucanas will lay them. If you want to show your birds or sell them as their specific breed honestly--unlike what the hatcheries do-- or if you just have a special color you want to see in your chicken yard--I love Wheaten!-- you'd want to get Ameraucanas or Araucanas through a breeder.
