I also make sure there's plenty of clover, plantain, comfrey, lambs quarters, and generally a nice variety of plants growing in the chicken yard. They love variety!
These are some medicinals I use to great effect for both prevention and curative reasons:
Echinacea seed
Comfrey leaf
elderberries...
Add herbal ingredients that are proven to stimulate the immune response, and either prevent or lessen the symptoms of viral outbreaks like elderberries, lemon balm, echinacea, licorice root, spilanthes & boneset flowers etc: administer as a decoction (boil for 20 mins things like seeds, bark &...
(1) Are you new to chickens / when did you first get chickens?
I'm a 61 year old farmer and have had chickens in my yard for 34 years ;-)
(2) How many chickens do you have right now?
13 birds this year. I had a flock of 22 chickens and 4 guineas get slaughtered in one night when a racoon broke...