Hi. I got my boy when he was 7 (and a half weeks too.) At first I fed him Canidae All Life Stages because I initially was gonna get a corgi, but ended up with a GSD instead (which has been the Best thing that's ever happened to me.) Canidae is an excellent brand, no corn no wheat no soy no by-products. A 44lb bag lasted for around 3 months. At 5 to 6 months, I notices he was VERY skinny, barely 40lb at that age. I decided to substitute a cup of dry food with 1 can of wet food (Alpo Chop House. Not the best but dogs have less sensitive issues with wet food.) and he looked SO GOOD after 2 weeks and he was approaching 50lb by that time. After that I switched to a specific Large Breed Puppy IAMS food, however it wasn't a No Corn No Wheat No Soy No By-products, but I gave it a go anyways. Good stools, reached the average healthy weight finally, BUT I noticed his coat looked terrible. Flaky and dull and shedded like CRAZY much more than usual. So I changed back to a no corn no wheat no soy no by-products, and he's doing fantastic now. (American Journey Salmon Large Breed) I also give him boiled sweet potato (important for his skin and fur), raw eggs and raw chicken livers every now and then. Don't wanna brag but he looks majestic now!
Bottom line, based on my experience:
1. Choose a LARGE BREED PUPPY specifically.
2. No corn, no wheat, no soy, no by-products.
3. Subtitute one cup of dry food with one can of wet food.
4. DON'T look at the brand per se. American Journey costs MUCH LESS ($30 for 28lb) than Nutro ($52 for 30lb) or Blue ($50 for 30lb). Look at the reviews and INGREDIENTS.
5. Spend 7-10 days if changing brands instead of 4-6 days... Trust me. I know.
6. Brands like Hill's, Royal Canin, Eukanuba are excellent on branding and marketing. If you look at their ingredients, you'll be surprised what is it that differrentiate them to Pedigree in the first place.
7. Feeding charts are ONLY GENERAL guide lines. Look at your dog and determine if he looks ok or not!
8. The right diet will result in shiny coat, bright eyes, perfect set of teeth, and of course firm stools.
Hope this helps!