Too much Calcium can be bad for a puppy

http://vetnutrition.tufts.edu/2017/02/confused-about-what-to-feed-your-large-breed-puppy-new-rules-may-help/
When Chrome was little and his mature weight is about 68 #s.  The Veterinarian warned me his joints were potentially outgrowing his body.  Ultimately this can cause looser joints at maturity.  I would prescribe to the thought that a large breed puppy is a puppy that matures at 50#s.  As I always council, keep your puppy thinner rather than fat, and use an appropriate diet for your large breed puppy. 
Tufts also has several articles about grain free foods.  Apparently some of these foods lack adequate Taurine, which has been linked to DCM and dogs.  Food For Thought!!!