Puppy's systems don't regulate calcium well until they are 6 months or older... and calcium is a big issue with our giant breed dogs. You don't want to feed a kibble with high calcium levels (>1.5%) and you don't want to supplement with calcium. The LOWER the calcium, the better for giant growing puppies.
That said..... all the studies on calcium effects have been done on kibble-fed puppies with calcium in a form that is highly processed and readily absorbed... I would hazard a guess that when fed whole, raw, bones as a source of calcium, puppies will only be able to gnaw off what they need and no more... and any excess will be recognized by the system and sent on through - just as nature designed it.
So... if you do feed raw, go with a basic "whole prey model raw" diet, including organ meats and appropriately sized raw-meaty-bones (I would even say no or low amounts of ground-in bone).
That would be my recommendation... but... Denna is my first raw-fed dog, and we didn't move her over to a raw diet until she was about 6 months old - just due to the slow pace of my research.
I know lots of people in the raw-feeding community wean litters of puppies straight to raw, so if you do it right, it should be a great way to go.
Also... flax... plant-based oils aren't normally something recommended for dogs. You can see if it helps, but if you see an increase in itchy skin or ear infections, I would blame the flax. I just started Denna on a new joint supplement which is flax-based, and after almost 2 years of being ear-dirt-free... we are battling another ear infection.
And I had previously blamed chicken. Nope. No more flax for us!! We'll stick with fish oils for our Omega 3's (and always provide Vit E with fish oil).