My situation has changed to where I have to keep my chickens penned. It didn't take long for them to eliminate the grass so I have to start feeding greens. Are there any greens, grasses, etc. that is toxic to chickens. In my area you can't let cows on Johnson grass with frost on it. The Prusic acid causes bloat. The Johnson grass is now very green and will not take long to get enough for the pens.