Welcome to permies.
It would help us
answer your questions if we knew where you were located, or at least a little bit about your climate.
An
herbal ley is a pasture that includes not only food, but also medicine for any animal.
In my opinion, any pasture (for any breed of animal) is incomplete if it does not contain its own 'medicine chest'.
Each species seems to know which plant is needed for each ailment that it may encounter.
(Humans are different...we seem to have had that knowledge bred out of us...probably by those who make money every time we have an ailment. They
profit by our not understanding what we need.)
An excellent book, by a veterinarian who practiced herbal medicine on 4 or 5 continents (including with gypsies) is
The Complete Herbal Handbook for Barn and Stable While the book is mostly about treatments, the knowledge about the herbs used for each species is a very good guide for what
should be included in your pasture to maintain healthy, vigorous animals. The woman practiced veterinary medicine for over 40 years, and never owned a syringe.