Not to be picking on Purina puppy chow but here are the ingredients. Notice that the first ingredient is a grain and not a meat. Second ingredient is a by-product so there isn't much protein left after it's dehadrated into dry food. If you compare that to something like Canidae all life stages, WOW what a difference!
Puppy Chow (large breed ingrendients)
Whole grain corn, chicken by-product meal, corn gluten meal, brewers rice, soybean meal, animal fat preserved with mixed-tocopherols (form of Vitamin E), barley, dried beet pulp, animal digest, calcium phosphate, calcium carbonate, fish oil, salt, potassium chloride, L-Lysine monohydrochloride, choline chloride, L-ascorbyl-2-polyphosphate (source of Vitamin C), zinc sulfate, Vitamin E supplement, zinc proteinate, ferrous sulfate, manganese sulfate, DL-Methionine, manganese proteinate, niacin, Vitamin A supplement, copper sulfate, copper proteinate, calcium pantothenate, garlic oil, pyridoxine hydrochloride, Vitamin B-12 supplement, thiamine mononitrate, riboflavin supplement, calcium iodate, Vitamin D-3 supplement, menadione sodium bisulfite complex (source of Vitamin K activity), folic acid, biotin, sodium selenite.
Canidae (all life stage) - a suggestion so that you don't have to transition from puppy food to adult food....
Chicken meal, turkey meal, lamb meal, brown rice, white rice, rice bran, peas, potatoes, oatmeal, cracked pearled barley, chicken fat (preserved with mixed tocopherols), millet, tomato pomace, natural flavor, flaxseed meal, ocean fish meal, choline chloride, suncured alfalfa meal, inulin (from chicory root), lecithin, sage extract, cranberries, beta-carotene, rosemary extract, sunflower oil, yucca schidigera extract, dried enterococcus faecium fermentation product, dried lactobacillus acidophilus fermentation product, dried lactobacillus casei fermentation product, dried lactobacillus plantarum fermentation product, dried trichoderma longibrachiatum fermentation extract, vitamin E supplement, iron proteinate, zinc proteinate, copper proteinate, ferrous sulfate, zinc sulfate, copper sulfate, potassium iodide, thiamine mononitrate, manganese proteinate, manganous oxide, ascorbic acid, vitamin A supplement, biotin, calcium pantothenate, manganese sulfate, sodium selenite, pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, riboflavin, vitamin D3 supplement, folic acid, papaya, pineapple.