How can I get my dogs to stop eating each others poo?

I have found a really good dog food for the dogs (4 English mastiffs - 2 are three years old and 2 are 1 year old) after a lot of research. They had this problem earlier in life - eating poop, but it seems on this new dog food they eat it even more than before, especially the pups. I hate to be gross, but when one of the older dogs are pooping, they can barely stop before one of the pups are trying to eat it. I read some info that suggested pumpkin and I've been using it for the last two weeks and the "habit" has not declined one bit. It may be worse. It is mostly the pups, but every so often one of the older ones will be caught doing it. We pick up the poo on a regular basis, but it's hard to stop them when it's barely come out of another dog's . Does anyone have any other ideas that have worked in stopping this nasty stuff?? I don't really want to go to pills from the store unless it's absolutely necessary because with their size one box would last like two days with my dogs.