Also remember a few things. The first couple of days is colostrum, which is more concentrated and kind of yellowish. Her udder may look full of milk, but really it's hormones causing edema, which will go down in a couple of days. Regular milk comes in about the second day - you can tell because all of a sudden the pups will be gulping and they might have milk mustaches and beards . Milk production is all about supply and demand, so avoid supplementing the puppies. Supply lags a just little behind demand. I don't feed extra stuff - I just give her puppy food and increase that as she needs it. I don't want to throw off any of the mineral and vitamin balances.
I use goat milk. The health benefits have been amazing in my labs, especially when weaning pups. My girls tend to have large litters so I want to make sure they get plenty of nutrition. I water it down so it is not to rich, cause it can cause loose stools. Also watering it down increases their water intake, a very good thing when feeding a large litter!
I have friends in labs who ask how I keep my pups so robust looking, I tell them its the milk!
It is also handy as my mother still raises goats!