No, protein levels have nothing to do with large breeds and their growth. Calcium and phosphorus ratios are the thing to be worried about when they are growing puppies, but your dog is also already done growing so you only need an adult dog food. Large breed adult food will only be larger in size usually. Since your dog is already done growing large breed food isn’t as important. But larger pieces of food for large mouths makes more sense to me.
Depending where you are located there are lots of different foods to try. I personally like Canidaes large breed food for all life stages. Any Canidae food is good though. Natures variety, merrick, and Canidae are good options to look at. If you want to stay With something lower priced then look at whole earth farms dog food or under the sun. They are made by merrick and Canidae but they’re value lines so a bit cheaper and still good quality.
