Remove the concentrates. He's not in work, he doesn't need them.
Put him on a basic grass hay, and just to keep him thinking he's getting a hard feed, give him a little white chaff with a pelleted or powdered supplement (in Australia we have Khonkes Own products - you might have a similar one in the US) to keep him on top of his vitamin/mineral needs.
With a suspensory injury, you do NOT want him fat. In fact it's better to have him a bit ribby than a bit too fat. Any excess weight, is extra weight those remaining 3 legs need to hold up. The more they have the carry, the more chance there is of injury to those legs.
He's not really on a lot of concentrate, and what's there is only there to mix his supplements in. :) Tomorrow I will be reducing his P.M. feeding of the Fiber Max Omega to half of what it currently is. He has a free choice himalayan salt lick, which, if I'm not mistaken, will cover the vitamin/mineral needs.
Now for the possibly stupid statement: I honestly don't know what white chaff is. It's possible that we don't have it here in California, or, more likely, I am just a complete idiot and don't know about it. Would switching him to pelleted rice bran be a good idea? What I like about Fiber Max Omega is that I feed very little of it, soak it, and it gains a lot in volume, so all the supplements mix in nicely. I feed a mere fraction of the actual, recommended serving of the feed, and, as I said before, just so that I can mix his supplements in. :)
I definitely understand the urgency of the situation, and I'm acting on it as quickly as I can. The grass hay should be delivered tomorrow, so I can start the transition immediately.
I also was wondering how much
grass hay I should be feeding. Would it be detrimental to his gut health for me to cut him back to 1.5%, or even 1% of his body weight? Would this be a warranted move, in the interest of him losing weight more quickly?