What a neat idea! In an earlier chapter of my life, I sprouted alfalfa seeds for sandwiches and salads. I'll have to try sprouting birdseed for our girls. They'll love it.Here's a picture of my sprouts right now. I have the Jiffy lid tilted so you can see the simple set up. The tall green one's are oats and ryegrass, and the brown seeds are wheat that I started about 3 days later. I have them on a plastic tub in front of a window.
No soil, just tap water and seeds. Other people have different set-ups, and rinse more often, soak longer, etc. This works for me and is 1x per day. You can feed to chickens at any point.