For chickens, you can sprout any of the seeds that are sold for sprouting, for humans. You can also sprout any of the whole seeds or grains that are sold for feeding the chickens. Seeds that are fresher and have been stored well, have better germination rates than seeds that are old.
Most sprouts can be fed at any time from when the root tip first appears, until they have leaves. The nutritional content will change in different ways, as the sprouts progress.
Beans are the one seed that must be fully sprouted, to be fed safely. You can't just do an over night soak and quick sprout, with beans. For them, you need to rinse and drain them daily and give them a few days to sprout more fully. Or, you can cook them, the same way that you cook raw unsprouted beans, to make them safe to feed.