If there are any dairy farms nearby go and ask for some colostrum milk from a recently calved cow, it's ok for piglets as a replacement and they can use the nutrients. Warm it up and then use a syringe to get it down their throats, in very small amounts, do not warm in a microwave as this kills off the good bacreria.
You can freeze any excess in an ice cube tray for later use, it will remain good for a couple of months.
I've used it before when I had a piglet that would not suck, it worked fine and after a couple of days the piglet got the idea, it survived ok.