Oats rarely sprout well (except in the paddock where you've had hay - for some reason they sprout really well there). Most of the oats that you buy from feed stores are clipped and dressed. It makes them transport much better but takes some of the kernel off the oat - they tend not to grow after that. The rare batch of oats that does sprout well has a tendency to go slimy and mouldy really easily. I think oats just like it much drier than the fodder system allows for (at least my fodder system).
You can grow most grains together. Some of them need something to grow into (like lupin or sunflower), you get around this by growing your base out of wheat or barley, the other grains put their roots through the root mat of the rest of the seeds - they just don't do well on their own. Seed them all at the same time though. Alfalfa and chia grow well with a base mat too.
Edited by beginnergirl - 9/8/15 at 6:10pm