Your point is good
@Becstasy94 .
Those who think that the only powerful versions of drugs and remedies have to be purchased or consumed in a pure, concentrated form might try
- at their own risk - picking euphorbia in sunshine, drinking grapefruit juice when on any one of 85 over-the-counter medicines, or eating any part of an arum lily.
I advise strongly against doing any of these things, but some people seem to be able to learn only by experience.
Nearly 50% of all drugs used today involve substances originally used as natural / herbal remedies, before laboratories existed.
To answer the original question directly, here's an article on which herbs to feed your chickens written by the BYC Project Manager
https://www.backyardchickens.com/articles/top-50-herbs-for-your-chickens.77443/