To keep them healthy... East of the mississippi the red cedar tree is common (Juniperus virginiana). Yes, it's actually a juniper... They have hard blue berries from time to time. The white coating you see on them is actually yeast, if you find a good strain you can culture it for bread making...
Anyway, I digress, if you have this tree on your property you are in luck. It's medicine, very old medicine. A couple of times a year I harvest and drop a handfull of these berries in the chicken waterer they drink from. It'll keep you chickens healthy along with most other farm critters for that matter...
A very good herbal medicine book for farm animals... “The Complete Herbal Handbook for Farm & Stable” by Juliette Levy... as useful now as the day it was published in 1954, still in print. I posted the book here.
https://www.homesteadingforum.org/threads/herbal-medicine-books-peanut-recommends.6745/
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