Personal experience: My coops are against the back wall of the main barn. Stall windows open above them and are inside the wire chicken run. I had a cute little hen who liked to fly up to the windows and escape into the barn. But she always came back.
One of my mares started eating poorly. At first she'd just leave a little feed but after a week or so, she wasn't eating at all. Never occurred to me that this had ANYTHING to do with my little hen, but one night the hen did not come back to the coop and instead roosted high in the barn. I climbed up and caught her and carried her back to the coop to keep the rat snakes from finding her. Then I nailed screening over the stall windows she'd been escaping through.
And the mare started eating again--ravenously.
The little hen had been laying in her feeder and I never gave it a thought, just collected the egg and poured in the mare's feed. After I closed off those windows with screening, the mare never went off her feed again. Maybe she didn't like the scent of the hen or something--I haven't a clue.
Point of all this? For every horse you find that does or likes something, you will find one who does not like the very same thing. You've just got to see what works with YOUR crew.
HTH
Rusty