Check your list of ingredients.
According to a trainer I know,if one of the first two listed is corn meal,then the food contains a lot of filler.Corn meal shouldn't be listed until the 3rd or 4th.She also had nothing good to say about Purina.She claimed Purina is very inconsistent with it's ingredients,changing the amounts and quality often to save as much money as possible.
I feed my dogs what she recommended,Natural Choice Nutro.