Hi Ivy
It is true that 40% protein it way to high for a large breed of dog, in fact almost any dog outside mushing dogs that need the high protein/high calories to run it is too high.
We know that anything over 35% protein in a food, most dogs are gonna put it to waste, but when dealing with Large breeds its even more prevalent that you control his growth rate and with a high protein food would be difficult.
The difference in the Timber/Orijen foods vs the Fromm brand and it protein discrepancy is because of the fact that the first 2 foods are what we call Grain Free, foods that utilize no rice, wheat, flour or corn in its production. Fromm does use a brown rice I think and maybe a pearled barley which is really a binding fiber.
Hope this works out for you, in your case you might want to continue to use the Fromm brand or look at foods like Canidae, Chicken Soup Large Breed puppy, Natural Balance, Wellness and Innova brands. They all make great foods that are between 24 - 30% protein yet will be considered Holistic foods without the usage of corn, wheat, flour and most importantly By-products.
STDT