Our vet, who raises mastiffs, suggested this to us:
Holistic Select Natural Dry Dog Food
We haven't had any problems and our Meatball loves it to death.
Although, on Saturday, he tried to convince me he loved used cat litter, too, so take that part with a grain of salt.
Definitely check with the breeder first. I feed this to my large breed puppy and it works well: http://www.amazon.com/Holistic-Select-Health-Oatmeal-30-Pound/dp/B003M5XJTY/ref=sr_1_1?ie=UTF8&qid=1421865257&sr=8-1&keywords=holistic+select+puppy+large
I was very happy with: