I personally don't think sprouting seeds for chickens is all that worthwhile, especially with sod squares so cheaply available, not to mention the fact that they can simply forage in any grassy or weedy area and get the same benefit. If you still would rather sprout seeds, I would suggest wheat grass greens instead. You can buy 50 pound sacks of wheat berries from organic food stores and other grocery or feed supplies. There are numerous Youtube how-to's available to show you the steps. IMHO, wheat grass offers far more benefits for chickens than sprouts.