I'm pretty sure you misheard. Pellets are the best thing (if there is such a thing) for a horse to choke on. As the horse works up the mucous, they are coated and can slide. Pellets also have no sharp edges - such as the hay cube Farmpony's horse choked on did. The hay stock can scratch the throat and an infection can result.
...and getting that tube in was a miserable task because the cubes are so compact that they take forever to saturate. If you were to take one and put it in a glass of water, the outside edges would be wet after several minutes but if you pulled the cube out, the inside would still be dry. Part of why it was so hard to get it down was becuase we couldn't get it wet enough and we couldn't get the tube past it. :(