AnnaC: That's interesting and something I've not heard before. My horses would be ENORMOUS if I fed any of them that much hay per day. I spread their hay out in 4 feedings, because I work from home and can do so. They get hay at 8am, noon, 3-4pm and between 6 and 8, depending on my schedule that day (my late afternoons/early evenings are often filled appointments and activities). Right now, they're getting roughly 1% of their combined body weight (8lbs). Every couple of days, one of the 2 three yr olds gets to spend time in the pasture with a muzzle along with our hard keeper. Our 4 year started rapidly gaining weight over the early part of the smmer (too much pasture time, even with a muzzle and then still too much hay) and her neck was getting thick and cresty. My poor friend (the farrier's wife) was beside herself with concern. As someone with a lot of experience with minis, I trusted her opinion that I had to change how I managed this particular horse. My changes have already produced results, thankfully.
We are lucky in that we don't have to worry about roaming dogs or wild animals that pose a danger in our area. They are kept in the barn/dry lot area overnight,