
Hi
As others have said, I would feed the pup exactly what the breeder has been feeding for a few weeks at least to avoid a major upset. Don't forget that the few weeks involve vaccinations as well as worming as well as major changes, so plenty of opportunity for upset.
Our last litter were raised on Arden Grange Puppy/Junior & they were the healthiest looking pups you could wish for. My own pup was put onto the adult Lamb & Rice at around 10 months as my adults are fed on it, and is still doing very well.
My daughter changed her bitch over to Fish4Dogs about 6 months ago, and is doing really well on it (won't try Arden Grange but that's daughters for you lol!). Fish4dogs would be my preferred 2nd choice, and it's done wonders for her dog as she was intolerant to some foods.