Is that what the breeder recommended?
The breeder just feed him optimum puppy thats it. I slowly transioned him onto black hawk puppy,pet mince,prime 100 meat roll and puppy milk.
Perhaps send some photos of your pup in varying positions to your breeder and get their opinion? Did you consult them on switching to the current diet, your breeder knows their lines and what they grow well on, they might have some suggestions of premium brands that work for their pups if you don't want to feed optimum.
You don't need to add extra pet mince and dog roll to a puppies dry food regularly. Puppy milk isn't generally needed either. A 10 week old puppy can chew. If you want to supplement with real meat, try meaty bones like chicken frames or turkey necks.
I'm not familiar with Black Hawk puppy so I'm not sure if it is suitable for a large breeds, perhaps someone else here might know.
I would definitely get in touch with the breeder. By adding too much fresh meat to the dry product it upsets the balance. I would also cut out the puppy milk. Be guided by your breeder. Far too often the breeder is the last to know of these problems when they can sometimes be fixed in a few days. Optimum is a fantastic product for Golden Retrievers.