Purina products use "pet grade" meat. This means that the meat used to create their foods was not fit for human consumption. This is often the fact with any brand of dog food you can buy in a major grocery chain or walmart. Pet Grade meats typically come from animals that have died of disease or had other issues. if you wouldn't eat a diseased animal then why would you feed your pets this?
Even though Chicken (or other meats) are the first ingredient on these types of dog food, they are listed by weight and the meat is weighed prior to cooking. The next ingredients after that are the ones which the food contains the most of.
Soybean Meal is not meant to be consumed by meat eating animals, which is why many dogs eating "store brand" dog foods will have LOTS of gas and loose stools to boot.
I could go down the list of each ingredient in these foods after years of experience working in the pet industry (as a vet tech and also in high end pet stores) but lets just say...for the LOVE OF YOUR PET please research what you're feeding them and do NOT just buy whats cheapest. We all love our animals and want them to live long healthy lives and we can help accomplish that with proper food quality. Spend a little extra every month for the health of your pet