There has been a problem with my horse's feeding: yesterday they flat out forgot to give him lunch, and today they just left the bucket of feed right in front of is stall in the dark. Nobody was around, and I wound up being the one to put it in his bucket. I almost missed it.
Never, ever, ever ever ever ever feed your horse without consulting the barn owner. Perhaps he was already fed and that was his breakfast for the morning.
When my barn owners are unable to feed they ask someone to do it for them; to insure there won't be any mix-ups they place the hay and feed infront of the stalls (of course the horses cannot reach it by any means) this way all the feeder needs to do is water and toss everyone their food...
You should not feed your horse without first asking the owner, this is common sense and proper boarding etiquette.