for commercial foods, we've always used Iams mixed with garden veggies (all dogs love carrots!) and an egg every couple days. I have two pits now, but my father has always had big dogs, currently has two saint bernards, but my favorite were the English Mastiffs. My girl growing up was Sam, and she was 194#'s, and she was smart and strong! make sure you don't work them to hard till they 2 years old, big dogs joints don't really develope as fast as smaller dogs