(Copied from the USAWE Website)
Working Equitation originated in Italy, Portugal, Spain, and France as a way to showcase horses used in the field and for ranchwork. The fourth and final test of Working Equitation team competitions is the Cattle trial, during which horses and riders must work as a team to sort and pen a designated cow.
The Cattle trial takes place in an enclosed arena with cattle-appropriate fencing (minimum size of 230 by 100 feet is recommended). During this trial, a team of three or four riders work together as each rider separates a designated cow from the herd and moves it across the enclosure to a holding pen.
Each person has three minutes to cut and herd their designated cow. Riders who fail to move their designated cow to the holding pen within the three minutes allowed receive “no time” (and therefore no points/awards) for the trial.
The fastest individual overall time (including any time penalties added) is placed highest in the Cattle Trial.
At this time, most Working Equitation competitions in the United States do not offer the Cattle Trial; however, several regions are starting to include the trial in some of their competitions.