Can I administer infant formula to my lactating dog?
LOL. No, and dont contribute it to the puppies either. Stop being cheap and go buy some doggie milk from Pet Co.
Giving your dog puppy chow at this stage is best for her. It have minerals and vitamins that will help your dog produce high quality milk for her pups. Let her munch through as much as she wants, as often as she wants. (She won't carry fat.) When she's done nursing, slowly put her back on her normal dog food.