
All our pregnant bitches were fed the same top quality food they normally have. As the due date approached and depending on how big she was, I'd cut back on the bulk, concentrating on extra protein, and instead of 2 meals a day, often fed several smaller meals over a 24 hour period (not during the night). I have never fed mum 'puppy food', while pregnant or post whelping - puppy food is for PUPPIES!! What I fed post-whelping depended on how many puppies she was catering for.
Apart from the fact that the puppies will be taking what they need from mum before arriving into the world, I'd be a bit concerned that she's ok if she's refusing all food. Is she drinking? Overfeeding mum before she's delivered her litter could simply result in overly big puppies which she might have difficulty delivering without help.