I would just like to add that the reason dog food started being made for puppies was because of the low quality of the kibble in the first place. Because of the all the fillers, it meant puppies had to over eat in order to get enough proper nourishment. Eventually the kibble companies came out with puppy formulas which were simply the adult version but with less filler. At some point, better quality dog food came out, then even better dog food. These high end versions did not make puppy food because they didn't need to. The high end versions did finally add puppy food because it is what people were looking for. Now, puppy food formulas usually have a slightly different composition than the regular, at least with the high end products.