My boy (a poor doing 16.2hh 3/4 TB 1/4 WB) is currently out at pasture 24/7. We've just moved yards a few weeks ago, from a place with very little to no grass, where he was on two scoops of a pre-made mix that was 8 parts chaff:2 parts rolled oats:2 parts barley: 2 parts wheat bran: 1 part pasture mix: 1 part conditioning mix plus Super Codlivine supplement plus free choice hay. He's actually looking in pretty good condition right now, with an actual top line (the first time since I got him!). He also gets worked pretty hard - I ride six times a week, with four of those sessions being jumping or schooling, and two being decent 1.5-2 hour hill rides - but before I moved him he was a working livery, so he would have three to four lessons a week on top of this, although I would only ride five times a week before.
I've just moved to a new yard around two weeks ago, which has plenty of grass, but it's not lush - it's long, stalky grass. So he's no longer getting hay, and he's now getting two feeds a day, each consisting of half a scoop of chaff, a quarter scoop of pasture mix, a third of a measuring cup of wheat bran, a half a measuring cup of (when dry) speedibeet (which is lower sugar than normal beet pulp) and is supplemented with Super Codlivine Joint supplement, garlic powder and salt.
My reasoning behind what I feed him is as so, but any comments or suggestions I am very much interested to hear as we are still experimenting.
Now he's on grass, I reason that he's getting plenty more than he was, so needing a less high energy feed. However, he's still in hard work, and the grass isn't too rich (aside from him begin a horse who would never do well on grass alone). Therefore, I keep his feed to being mainly chaff, in a similar ratio to his previous feed, but cut out the oats and barley as he's getting more from the grass now. I keep him on the speedibeet because it's high in fibre-based energy, as well as easy on his digestive system (he can be colicky) and balance this with the wheat bran, which being high in phosphorus balances out the high calcium levels in beet pulp, and is also good for his digestive system. The pasture mix is supposed to be only a light work feed, but it's really appetising, and gives him some extra energy without being too much. Overall, he gets around the same volume of feed as before, so hopefully he's going to do as well with this mix as he did on the higher energy mix, but it's less heating and balanced out by actual grass instead of hay.
The pasture he's on is not deficient in anything, so the Super Codlivine is fine for a supplement as it's a pretty good all-round supplement with extra MSM and evening primrose oil for his joints (he's an older lad). The garlic is just to make his feed attractive, and the salt because horses can't go wrong with a little added salt.
Bit of an essay, but any feedback would be good. Come winter I'll probably add oats to his feed again, as well as upping volume a little, and he'll go onto haylage.