
Just to say puppies do poo a lot, if it is formed this is not excessive, they are eating more than an adult of their breed at this age.
What goes in has to be processed and come out.
You will get different ideas on the ideal puppy food so I would stick to what he was reared on for a while yet and only introduce something new gradually.
He will be having a lot of changes, change of home, water, environment, be subjected to worming treatments (possibly flea treatment) and having vaccinations, so best to keep the food familiar at least for a while.