Eating poop is a fairly normal (yet disgusting) thing for a dane puppy to do. The ONLY way you will be able to curb this habit is to be diligent and pick up after her when she goes potty. I suggest you go to Petsmart and invest in a box or container of small pick up baggies and every time you let her out, do the pickup right then and there. There is no "magic cure", suppliment, vitamin or food that will stop her from doing this. The only "magic cure" is you spending the 5 minutes it takes to do yard duty each and every single day.
All you will get by investing in an electric collar, for a 5 month old dane puppy, is a socially destroyed and distrustful animal. It takes more time to use one of those shock collars than it does to pick up a pile of poop. I cannot stress enough how much damage you would do by using a shock collar to a puppy this young (or a dane of ANY age for that matter). Your breeder should also be giving you advice on training your new puppy and should be a wealth of information for you.
Yelling at her will make no difference. A young dane puppy should NEVER be yelled at, as they are a very sensitive breed and you will end up with a dog that doesn't pay attention to you at all.
I don't mean to sound harsh, but you need to make time in your schedule to ensure your puppy isn't getting into things that she shouldn't. Time management is a wonderful thing, and it takes only a few seconds to lean down, and pick up her stool when she goes. I have also seen first hand results of using shock collars on young dane puppies and it is NOT a pretty sight.
Caroline Smith
FarView Great Danes