I have never heard of using boiled rice to add weight. As I posted in your other post, for many animals and humans, rice is/can be used to stop constipation. IMO the risk of colic is high. I would not use it. Rice BRAN is totally fine. It comes in powder form and pellet. (I prefer the pellet) It is high in fat and many use it to add calories/put on weight in a horse.