This weekend, the Professional Bull Riders (PBR) will bring some of the sport’s toughest athletes to the Broadmoor World Arena for the “Built Ford Tough Rumble in the Rockies.” Oh, and the bull riders will be there, too.

At 7 p.m., Saturday, the Top 35 cowboys of the PBR will face off against the Top 35 Classic bulls. Fans also have the chance to see bucking bulls Long John, Stone Sober, Mississippi Hippy and Bruiser in the arena, all of which are in the running to claim the PBR World Champion Bull title for 2015.

The PBR's Built Ford Tough Series is the most elite level at which both cowboys and bulls compete. Each eight-second ride sees fierce competition from two extraordinary athletes. If a cowboy makes it to the whistle, the score he receives (1-100 points) is based on his and the bull’s performance. Even if the cowboy gets bucked off before the whistle, the bull still receives a score, which is recorded and tracked as intently as the cowboys' stats.

While bull riders start competing at 18, bulls typically start their careers when they turn two, and, by ages three or four, might have already made it onto the Built Ford Tough Series stage. Any bull that bucks on the elite Built Ford Tough Series must pass inspection by Cody Lambert, PBR co-founder and livestock director, as well as former champion bull rider. No bull can make it onto the sport's biggest stage without his blessing, and any animal who gives a lackluster performance will not be invited back.

Many of the PBR's bulls launch their careers by competing in American Bucking Bull, Inc. (ABBI) events. ABBI is a PBR sister company dedicated to developing the animal side of the ride. In their first year in the arena, bulls buck with a weighted box – called a dummy – on their backs for four seconds, competing for cash prizes. After its third birthday, a bull can start challenging human opponents at the ABBI Classic Level for two years. ABBI pays out more than $2 million in prize money to young bulls each year at this level.

ABBI Classic events are held in conjunction with PBR Built Ford Tough Series events, meaning though these younger bulls are still developing into elite athletes, they are tough enough to face the Top 35 bull riders in the world. Most superstar bulls of the last decade got their start in the ABBI. Bushwacker, the three-time PBR World Champion Bull, considered by many to be the greatest bull of all time, is a former ABBI Classic Champion.

The American Bucking Bull is now a registered cattle breed. Unlike other breeds that are set apart by certain, physical attributes, bucking bulls are born. They come from bucking parents and follow in their footsteps, building careers and names for themselves. Most modern bucking bulls are a mix of several breeds of cattle that have been carefully bred for generations to exhibit traits required of elite bovine athletes.

These animal athletes’ bloodlines are so highly valued that American Bucking Bull, Inc. (ABBI) has a DNA registry of over 170,000 registered bucking cattle. By tracking animals and their offspring, it becomes apparent which genetic combinations make for better bucking bulls. Worth as much as $500,000, bucking bulls receive the best possible care from veterinarians, chiropractors and acupuncturists who specialize in treating bucking bulls. The Bull Pool in Canton, Texas, even provides conditioning and training services for bulls who need to beef up and rehabilitation options for those recovering from injury.