It's not what's in the hay. It's when it's cut, the land it's grown on, and most importantly how it's stored. I can take great alfalfa and make junk out of it. My mom does it every cutting because they don't fertilize the field after growing corn on it, cut it late so the stems are long and hollow, and then let it sit in the sun so it turns brown. It's wonderful looking stuff in the field and I won't feed a bale of it to my rabbits cause it's pointless. They wouldn't eat it the way it's been handled. Our organic clover hay gets the field treated with trace minerals yearly, is cut at the right time even if that means getting only a small amount of hay because it's not very tall yet, and is immediately put up in a dark building. It is the densest hay you will ever see. I picked up a handful and actually said "wow" because it is so firm and the guy tests it by eating a stem to see if it's chewy and sweet. Too few people know how to properly handle hay for the more sensitive livestock. It takes forever to track down someone who really knows what they are doing. I used to order hay from washington state and nebraska in bulk at $1/lb because I couldn't find good enough hay here and there's hay everywhere.