LOL, guess I'm not the only one with a gassy horse. Gilbert does it all the time. I figured it was just his age because my 2 younger horses hardly ever toot their horn while being ridden.
I remember the 1st time we went to the saddle club and I was riding him in the arena. While posting I always count to myself 1, 2, 3, 4. Every time I got to 4 he would fart. The announcer said, I guess Dorothy found her gas pedal." LOL the kids got a kick out of it.
I let a 7 year old girl ride my horse in western pleasure. Just before she entered the arena she said, "I won't step on the gas, I'll sit the trot."
Turned out it was the tifton 44. I mostly give them mixed grass hay, but sometimes I treat them to tifton. I stopped giving them the tifton. The gas pedal is still there, but he does it a lot less.