I found one that that helps with really runny poo that I gave my pullets last summer when it was heat related runny poo. I had a box of the gerber baby fllaked rice. Looks like flakes. I added enough probiotic and electrolyte water to make it pasty and made sure it was all rehydrated. I added a bit of crumbles. They ate it up the next day no more runny poo. I gave it to them every other day for about 5 days when I ran out. They didn't have it again.
I figured vet told me to give it to a kitten mixed with wet food that had severe diarrehea that it would work for a chicken too. Besides they give it to human babies for the same thing.
Now I keep a box on hand, I give them some after they been wormed. Or as I give them the meds so it doesnt just go straight through the digestive system.