So this is what I've done the last two seasons. Everyone here knows I'm a rookie, so take it for what it's worth:
I pack individual ziplock bags with a "Ration." The ration mix is:
-- 1lbs rolled barley
-- 1lbs Max E Glo (pelletized rice bran)
For a total of 2lbs per ziplock bag. I bring 2x ration bags per day, per horse. (Read: 4lbs total of ration per day, per horse.)
I feed using a nose bag, with the following timeline:
-- Bag 1: 1/3rd in the AM, about 30min before hitting the trail.
-- Bag 1: Remaining 2/3rds around noon.
-- Bag 2: Full ration, late afternoon/early evening (if I'm not out hunting - otherwise they get the rest back at camp.)
This is all supplemented with grazing, using hobbles. I let the guys graze as soon as I wake up, they get an afternoon graze (usually while I'm glassing), and then I let them eat as long as I can in the evening, before highlining them for the night.
Some things of note:
-- I bring a small peanut butter jar filled with stock salt, and make sure my guys eat some of that every day. This makes them want to drink water. I want to make sure they have lots of water when they are on their rations.
-- I read in a few different places that barley has way more energy than oats, for the same weight. So I run barley instead of oats for that reason.
-- Don't feed heavy amounts of grain first thing in the morning. It seems to mess with the horses and makes them lazy. Stick to just a little bit in the morning, and then feed the rest afternoon/evening.
-- The barley is for cheap energy, and the Max E Glo is for fat. In theory this helps keep condition on the ponies by providing easy energy, plus some fat for reserve.
-- The 2lbs bags make it easy to plan meals for the horses, and balance panniers. If you're light on one side, but heavy on the other, just swap a ziplock bag or two.
-- If you get hammered with a heavy snow, and the grass is all covered and awful, you can still "get by" for a day or two with just your grain. Without it, your ponies will start to get really hangry and start thinking about leaving.
This type of feeding isn't a replacement for grass/grazing. My type of excursions are generally fair-weather, 3-day/2-night type of deals usually, so the combination of the rations plus grazing keeps the horses at 90% or so. But if you were to try this for 2-week trips, it's likely your horse(s) would lose condition.
I forget which book it was that said "It's better to count ribs than tracks", meaning it's better that your horse goes skinny (being tied up at night) instead of risking your horse wandering off in the night while hobbled and grazing. I figure 3-4 days on rations is fine - My guys are pretty spoiled the rest of the time and get more than enough feed at home.
Oh yeah, and ease into this. Start feeding them this stuff in small amounts about a month before your trips, just so their stomachs are used to it.
