Our brother, Dr. Manger, and his wife Carol an RN, run a small farm, about 30 acres, in Western Maryland with horses, chickens, goats, llamas, and sheep. Carol brought in goats to "groom" the pastures of unwanted vegetation and found they did not like thistles and other thorny weeds. She then brought in sheep and they ate everything, even under the electric fencing before being shorn!
The llamas were brought in to take care of eastern coyotes that threatened the chicks, goats and sheep. They were good at the job.