My breeder is currently feeding my pup a diet of Life's Abundance grain free puppy food. If I could keep him on that I would...but it is VERY expensive! A 30 lb bag is $90...I have to feed him the best I can afford. I was considering Purina, but then found out that American Journey is pretty affordable and is a MUCH better food. The kind I have picked out has grains though, which I don't think will be much of an issue health wise...but I don't want to shock his little system switching to his first grains ever too fast. Does the change over need to be slower, or will a typical food transition/mixer work?