I've only ever changed to puppy food in the last 2-3 weeks, when the bitch is eating less anyway. Never had a 'normal' litter - the pups have always been about 2x breed average weight and size and really lusty
Personally, I think if her breeding produces bigger pups then
she's more likely ;) - that's how it worked when I bred cats.
I wouldn't feed 'extra' calcium as it could predispose towards eclampsia, but don't know about too many bones - how many is too many??
As pups bones aren't fully 'finished' I doubt that extra bones eaten by mum would make the pup harder to deliver, I'd be more worried about the
balance between the bones and the rest of her diet, as I understand it that's more important than 'how many'
Hopefully someone who Breeds
and Barfs will be along soon to put us both right ;)