What about puppies eating their own poop? What is the reason?

The dog is a dog with a problem with the gastrointestinal absorption, eating poo to replenish the body’s nutrition. 2, the dog can not eat enough food, can only eat feces to replenish energy. 3, the dog’s body inside the lack of trace elements, omnivorous. 4, the puppy followed the big dog did not learn well, see the big dog eat, they also eat. The dog’s body is deficient in micronutrients. 1.