Practically every dog eats poop. It's a dog thing. Yea, it's disgusting, I agree. But, you do NOT need to use a shock collar to train it out of them!
I'd try 2 things: 1. re-train them to go potty at your command, and only in one area of the yard. At which point, you can pick it up and toss it in the garbage. You can leave a garbage pail out there, by the spot, so you don't have to bring it into the house. Yes, it's a pain in the butt to retrain and then pick up after them. But, no poop = no problem. This is what I did with my dog, from the time I got him. He goes in one spot, that I indicate on command. I pick up after him, and that's that.
2. Teach them the "leave it" or "drop it" command. Once they know it, without fail, try using it on them each time you see them pick up poop.