Pregnant nursing and growing goats get alfalfa. If not oat hay is my main choice but also did very well with wheat and rye hay. If the rye is cut before it comes to head its actually very good hay. More protein then alfalfa but about 2/3 of the calcium.
I haven't seen any creature that wastes more hay than goats. Drives ya nuts. I like to free choice, but when I do they waste a lot of it. I'm trying to come up with some idea for a big square bale feeder, but haven't gotten it figured out yet.