pedigree is one of the really low quality brands of dog food. just to illustrate and example (we'll make it easy and leave out the vitamins and mineral supplements):
here is the ingredient list of "pedigree healthy start" puppy food:
Ground yellow corn, chicken by-product meal, rice, corn gluten meal, animal fat, natural poultry flavor, wheat, potassium chloride, dicalcium phosphate, salt, brewers dried yeast, wheat flour, caramel color, wheat gluten, vegetable oil, calcium carbonate, taurine, vitamins, minerals
and here's a quality chicken-based puppy food, "healthwise":
Chicken meal, ground brown rice, oatmeal (rolled oats), chicken fat, flaxseed meal, natural chicken flavor, herring oil, avocado oil, garlic, dried kelp, vitamins, minerals
ingredients are listed by descending weight as they appear before processing. you ssee that the pedigree has a grain source (corn) as a first ingredient, not a meat source - as it should be for an animal with a carnivorous background. we are not trying to feed a cown here.
the second ingredient in pedigree is "chicken byproduct meal". chicken byproducts are basically what is left over of a chicken after all the quality muscle meat has been removed from the carcass. the good meat is used for human food, the stripped leftovers are rendered into pet food.
pedigree contains generic "animal fat" and "poultry flavor" - two items that do not define the exact source they came from and so can include a variety of things, and not all of them are necessrily very desirable. "animal fat" is so generic that inclusion of animals like roadkill, diseased animals declared not fit for human consumption, animals euthanized at shelters and vet clinics, restaurant grease, supermarket refuse and so on.
i don't want to go into too much detail here, you can read more abotu commercial pet food if you click on the blue part of my signature.
you can switch your dog to a better food at any time.