Hi! At first, I have to apologize on my english, I dont speak english very well.
I feed my berner with Royal Canin for giant dogs, its the best dry food I can get here in Croatia and he loves it. He also loves fresh fruit so we give him some fruit as treats.
Berners also have troubles with their eyes, so you should look for lines with healthy eyes, my Berg has cronic folicular konjuctivitis (Im not sure its called that way in english), it is inflamed foliculs on third eyelid and we are treating that since we got him.
It is very important to see how puppies are kept in breeders home, they should not go up and especially down the stairs or hills. You should prevent that until he is at least 6 months old.
The best exercise for young puppy is tug-of-war, that way he is getting good exercise and he is also having a quality time with you. He should also play with other puppies and dogs as much as possible.
Lot of people think that berners are not active dogs, but they are very active. Good exercise is also swimming because it does not pressure the joints, but my dog doesnt like to swim.
It is very important not to physicaly strain your dog until the age of around 36 months.
It is also very important to train your dog obediance from the first day, berners are very loving and gentle dogs, almost as they dont need any training at all, but if you neglect their training, sweet puppy will soon turn into your biggest disappointment.
Berg is now almost 7 monts old and he weights around 45 kg (100 pounds), I never had any problems with his size, probably because I tried to teach him not to do anything I supposed it could be a problem when he gets bigger and heavier. But I do have a problem with his wagging tail, he always knocks down everything off the coffee table!