When a food is to high in protein it will come out smelling like food to the dog and it will eat it. Try a food lower in protein and add fresh pineapple to his diet. The pineapple will make the poo taste bad.
How Can I Stop My Beagle Puppy Eating His Own Poo?
This behaviour is called coprophagia, and it is normal in dogs, especially puppies. Most dogs grow out of it, but in the meantime, the best way to avoid the problem is to prevent opportunity by regularly removing all faeces from the environment. Consider feeding your dog smaller more frequent meals to eliminate hunger problems. It is also possible to train your dog. If you catch him in the act, or just before, yell out to attract his attention. Reward him with affection and treats when he stops the behaviour.