Well, here are the ingredients for the ProPlan chicken and rice puppy formula served up here in the US. Corn and maize are probably the same under different names. And many, many, many reputable breeders feed and send puppies home on ProPlan puppy.
>>Chicken, brewer's rice, poultry by product meal (natural source of glucosamine), corn gluten meal, whole grain wheat, animal fat preserved with mixed tocopherols (form of Vitamin E), whole grain corn, corn germ meal, brewer's dried yeast, fish meal (natural source of glucosamine), animal digest, dried egg product, fish oil, salt, potassium chloride, calcium carbonate, calcium phosphate, choline chloride, zinc sulfate, Vitamin E supplement, ferrous sulfate, niacin, manganese sulfate, L Lysine monohydrochloride, Vitamin A supplement, calcium pantothenate, thiamine mononitrate, copper sulfate, riboflavin supplement, garlic oil, Vitamin B 12 supplement, pyridoxine hydrochloride, folic acid, Vitamin D 3 supplement, calcium iodate, biotin, menadione sodium bisulfite complex (source of Vitamin K activity), and sodium selenite<<