@FunkyGibbon They do indeed appear to be ragwort, I'm curious how they can keep them in there without issues from it. I have however read that horses will only eat ragwort when there is little else to eat, but I'm not sure how true it is.
@Macaw16 According to a little research the real danger lies when the plants are young or dead and have lost their bitterness. I know that when my family kept horses when I was young my mother went to extraordinary lengths to keep it out of the paddock.
I think the only reasonable conclusion is the Przewalski's aren't affected by it in the same way.
