What is this western riding/rodeo game called?

I was just watching the horse shows at my county fair. There was a herd of cattle at one end of the ring with numbers on their necks. 4 horses and riders came in and the judge called out two numbers and the riders had to single out those cows and move them into a trailer. One person had to jump off and close a separator behind the cows. Get their horse in and close the door. They had to run to the front of the trailer and grab a string or touch the gate to make the time stop. It seemed like team penning but i thought that their were only 3 horses in team penning.