It turned out to be lots of fun. Basically there are two riders that enter two pens separated by an opening about the width of a gate. One one side there are 10 cows bunched and as soon as the riders cross through the gate a number is called out and they have to pick that cow out and sort it into the other pen. You then continue in chronological order until time runs out or all the cows have been sorted. If a cow comes back or the wrong number goes through you don't get a time.
There was this one little chestnut horse that I absolutely adored. She (I think) had some serious moves and even saved some rides when a cow was sneaking up behind and the rider didn't see. It made me almost miss having a cow horse. They are fun rides and you learn to keep your butt in the tack and feel your horse. Hopefully we will get to go back, because I had a blast and the people were super friendly (despite me showing up in breeches).