Are you aware that most pet food manufactures are owned by companies that also make human food products? It makes perfect business sense. Scraps, waste or other food by products can be sent to the pet food manufacturing processing facilities.
Using less nutritious products to start with along with the process to produce dry dog food. The result is that most of the nutrients are missing. To fortify the product, they chemically add nutrients. The altered product, proteins and nutrients, can contribute to many food allergies or other harmful medical problems to your pet.
To learn more about this click on this link.