Hay bags are great if you have the patience to fill them and hang them safely.
My barn uses hay mangers in the stall and round bale feeders with slow feed nets over the round bales outside. The slow feeds cut down the waste to almost zero because they keep the horses from pulling hay out of the feeder and spreading it around/pooping on it. The mangers do a similar thing in the stalls.
I know there are square bale feeders that are slow feed on the market which may be a good option for your Arabians. I would just make sure to put them in something or hang from a fence so there is less risk of a horse getting hung up on the net – especially if they wear shoes. I’ve heard of people who have barefoot horses putting the nets on the ground, but I would (knowing horses – they always get in to trouble!) secure the net into a feeder, bucket or other container. The nets keep them from eating their hay too quickly and getting bored and would cut down on waste.
Visit my horse care and product review blog at: www.keepcalmhorsecare.blogspot.com