Oops, sorry....I should have explained.
IR is similar to type II diabetes in humans. Certain breeds are predisposed, ponies, Arabs, for example, the famous easy keepers in general. Once overloaded with sugars means high risk for laminitis/founder.
NSC's you want as low as possible for an IR horse, around 11% for all feed given.
As examples: oats:44%, corn 73%, the average pelleted feed anywhere from 11-35%, Omolene a whopping 40%. Grass hay 13%, alfalfa 11%, grain hays 20-22%.
Grass as in pasture is even trickier, after a cold night on a sunny day super high, stressed grass very high, short, drought.
It doesn't help that man is planting grass for production, I.e. milk or meat. Hence my wish for natural pasture.....