They will eat everything they can reach, to include, Poison Ivy.
We had first purchased a goat because I read that they could eat poison ivy without harm. Having a lake in the back yard that we intended to fish, I did not want to spray Round Up or other weed killers to clear the ivy out. But I had to do something, the dogs would run through it chasing everything fluffy and then come into the house and get on the furniture. I would come home from work, sit on the same furniture and presto – I got Poison Ivy, again.
Within a month we purchased three more goats and then the clearing began. Those goats ate down a half acre of poison ivy in the following months. As fast as it would grow, the goats would eat it down.
That was a 4 years ago and our goat herd has grown a bit. They now maintain over 1,000 feet of shoreline and 60% of our land with their appetites. Weed-eating around the edges – done. Brush clearing – done. Pruning trees to within goat reach (about 6 feet when they stand on their rear legs, or each other) – done.