it is actually a very simple structure. You can do the same thing with only 1 coop, since animals are able to stand "inside" each other. just watch out for animals escaping from the coops. They sometimes do that somehow.
Also, I found a way to automate the pistons in my farm: Just leave a single chicken running around inside! It will wander, and every now and then step on the pressure pad and activate the pistons!
Hehe I prefer to give my chickens more space and use less redstone. (I'm trying to stay mainly above ground) I only have one chicken as of now but I'm hoping eventually one of its eggs will yield another chicken. With the power arrows provide chickens will no doubt become my main resource in the plains region. If someone could answer my other question on the animal husbandry thread that would be nice.
I was doing chicken farming long before 1.8 to gather eggs to make builds out of cake (yes out of cake..) only difference now is they drop food and they don't despawn so i don't have to actually stand there and babysit them!
I have noticed a bit more lag when I am in my house.
But that's not the worst of it..
Oh god, the clucking. So, so much clucking! I'm surprised my Steve? can even sleep!
I would suggest making your chicken farm a decent distance away from your house.
Now, on another note:
Could someone try to come up with a way to auto-harvest the eggs without letting chickens loose? I can't figure it out.
To auto harvest the eggs :
(I haven't done this in awhile [and I suck at describing things], so hoping this is right)
Make a 2x however big you want it hole, dig down at least 5 or 6 blocks.
Use signs on the blocks below the last layer where the water would go.
Now place the water, starting on the lowest layer of water (on top of the signs)
After you have placed all the water, you should have 2 solid layers of still water and air underneath.
Set up that area underneath however you like for collection. (I put flowing water to bring the eggs to a collection point, like for a mob trap)
Back on the surface, block the chickens escape, leaving them nowhere but the water to go in.
The chickens will swim on the water, and not go down. The eggs will fall through the water to be collected.
(I am not good at these smilie pictures!)
Water is water, Picture frame is sign, glass is empty air, sheep is chicken, diamond is egg.
...I'm sorry to burst your bubble, but 1.8 certainly does not have persistent animals. I've killed many a cow, chicken and pig around my house and yet they continue to spawn. Same is to be said for hostile mobs. If you leave the chickens alone long enough, they will despawn.