We recently are feeding our 13wk old puppy IAMs proactive puppy food. We found out its not the best with all the fillers and are starting to run low on it. So we went out and bought Blue Buffalo Life Protection Formula for Puppies, which we heard was a great brand. We just aren't too sure how much of the old food to give him and how much new. And how long should it take to fully switch out. Please help us!
-Zach and Lisa