Rice bran is common. It's made by grinding up the rice hulls and "leavings" after rice has been processed for human use. You can buy it in powdered or pelleted form.
Rice hulls are sometimes used as beding here. I know some barns near a big rice plant that can get them cheaper than shavings and they seem to work well. The horses will sometimes eat them, but they're not "tasty" enough for the horses to eat much. Cows will eat rice hulls though.
I've never heard of feeding actual rice to horses. Was is hard like human food rice? Or was it processed in some way?
"To be an equestrian in the classical sense is not just to be a rider. It is a position in life." --Charles de Kunffy
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