Soy infant formula (grocery store or pharmacy) is recommended as it is the closet thing to mama rat's milk.
Tiny babies will lick it off the end of a needless syringe or off your finger.
Older babies will lick it from a shallow saucer.
You can thicken it with a bit of baby cereal (the kind that says add formula).
Do they all have their eyes open? If so, they are likely over 2 weeks as eyes open at about 14 days old.
Here is a thread that gives several links to raising orphaned baby rats.
viewtopic.php?f=26&t=27608
Hopefully some of the members on here that live in NS will be able to help, 23 orphaned babies is a lot to care for.
Soaking good quality lab blocks (oxbow, harlan tech 2014 or living world hamster extrusian) in soy formula or cool water, will turn it into mush for the babies to eat.
You will want to make sure they have access at all times to soy infant formula, mushy lab blocks, regular lab blocks and water.
Baby rats need to have shallow water dishes as they are not strong enough to move the ball bearing in water bottles, although they may loonk like they are drinking they will be unable to actually get water out of a water bottle until they are several months old.
A site that might be of interest:
http://ratgrowth.homestead.com/
Some baby threads:
http://ratshackforum.com/forum/viewtopi ... m&start=60
http://ratshackforum.com/forum/viewtopi ... r&start=75