green roofs for chickens

This is a great idea. I have chickens at home and i have been needing to rebuild a chicken coop so i think that i might have use this example as a design idea. i might have to put some wheels on it so that i can move it around the farm. Chickens love fresh green grass, as long as they dont get out and eat the vegetaion on the roof, unless they provide great fertilizer for the roof while eating.