, based on the verbiage in the OP's post, I feel like she? is from across the Big Pond somewhere. Thus the reason for the different terms
I looked up microlupens and that is a feed product from Australia. Hygain Micrlupins - Micronized lupins
It sounds like a good feed but looking at the 34% protein, it then begins to sound a like a contradiction
In the U.S. the protein source for 99.9% of bagged feeds and ration balancers is soy.
I don't have a clue what the protein source would be for a feed made in Australia. That very high protein may innocently be part of the problem.
The G/A also does not list the ingredients. If it's full of the proverbial "roughage products".
The product is called "flakes"; looking at the picture it resembles our human cereal of corn flakes.
Again, looks quite good reading the bag, but mehbee not good at all when dealing with ulcers.
Perhaps a complete diet change of what goes in the feed pan (including not
feeding the apple cider vinegar or garlic) is best until the horse can be scoped.
I have a horse with mild gastric stomach ulcers and he cannot handle garlic or ACV.