thanks for the responses everyone. They all made it through the night...
So, plain yogurt. Any certain brand or anything to look for? Or just run of the mill stuff?
I hate being 'that guy'--the first-time poster with an emergency. But I'm housesitting, never taken care of chickens before, and did something stupid: I fed the hens (11 adults) some slightly moldy tortillas. The lady I'm housesitting for said they basically eat anything, that she uses them...