Using cow manure in the garden, or horse, can be very beneficial adding nutrients to the soil.
However, manure contaminated with herbicides, such as aminopyralids, can destroy a garden for months. This video is about how to tell if horse manure is contaminated, or any manure. Specifically, how to test manure to make sure its safe for garden

Link to poison graphic https://www.freepik.com/free-vector/c...