Lot of hits but no replies yet. So here we go from my point-of-view since my 26 yo Arab has mild gastric ulcers and my 25 yo TWH has hind gut ulcers, lipomas and Equine Metabolic Syndrome
My Arab's stomach ulcers will generally flare up toward the end of winter. I would also give him Ranitidine but, he's only 13.3H and ~840 lbs so got 16/daily. It finally ended up that it was just easier and better for him if I bought 30 days of banana flavored, liquid Omeprazole from the vet --- at $150
My horses don't get grain (more on that later). My Arab's flare-ups are caused by not having enough green grass. I can hunt down and feed him all the "Prime Rib" grass hay that I want and it doesn't help by the end of winter.
What has helped to keep him off ulcer meds these last two years is feeding him well-soaked timothy/alfalfa cubes. I buy Standless from Tractor Supply.
They need to be soaked so the horse doesn't choke but my Arab's are "well-soaked" and hand-broke into wet grass because he has four molars missing.
Right now he gets ~one pound in the AM. Somewhere thru winter, I will add another pound in the evening. He's been with me 19+ years so I have learned to tell when his tummy is getting uncomfortable. If I try feeding him two pounds a day, all year long, he refuses to eat it
He's also a persnicketty little Old Curmudgeon - lol
He also gets a ration balancer and equine rice bran. Rice bran because he is a hard keeper. Rice is 22% healthy fat and provides cool energy to the horse.
I buy Manna Pro's "Maxi-Glo" also at Tractor supply. It comes in meal or pellet form. I use pellets.
Regarding the Strategy: It is not a ration balancer; it is a grain-based feed. I would get him off it. If Purina is your only choice or it's your preference, their Enrich 32 is their ration balancer.
The ration balancer that I feed my Arab is Triple Crown's 30% BUT he doesn't like it and oddly enough, neither did my 25 yr old. Equine Supplement-Triple Crown Pelleted 30% Equine Supplement
I am mixing in a bit of Triple Crown's Senior until I get all the 30% used up. I plan on calling TC and asking what's in there that makes it taste yukky to two of my horses Senior Horse Feed | Triple Crown Senior Horse Feed Formula Helps Keep Older Horses Healthier
The grain products are far down the Ingredients list and are "dried" grains.
I prefer Triple Crown because they list their ingredients; Purina and Nutrena do not and I don't like that.
You may have some other high quality vit/min supplement or ration balancer in your area that you can switch to. Whatever you feed, I would add the rice bran.
Omega-3 Horseshine (flax) might also be good for him. Tractor Supply carries that, too
If the Ranitidine is keeping your horse under control, the Ulcer Gard should work for him.
IMHO, I think it would help to add some alfalfa but I would add the timothy/alfalfa cubes at one or two pounds daily and see what happens. I weigh them dry, then add cold water no more than 30 minutes before feeding in this heat so they don't turn sour.
My horse with the hind-gut ulcers is on Succeed ----- at $3/day
Here's the link to read up on it but this is serious ulcer medication and a site I might bookmark in case you need something stronger down the road. You don't need a prescription for this like you do EquiOtic.
Valley Vet sells Succeed. SUCCEED Digestive Conditioning Program Equine Supplement
So the bottom line is to try and feed him the smallest amount of feed possible, while still providing him with healthy energy and fat. Of course all the grass hay and fresh grass he can handle is needed because horses are forage animals first.
Hope this helps you a little