Toxicity in Spring Madia (madia elegans) or Elegant Tarweed

I am hoping to reclaim several pasture areas that have been left fallow for decades by previous owners. I am hoping my young AGH pigs will be helpful in starting the process. They made short work of the pen area , approx 16' x 36'. The first pasture we want to begin working on has Spring Madia growing rampantly in it right now. I have been unable to find any information on whether this plant is toxic to pigs. Does anyone have any knowledge or experience with this plant?