Bryce Derrer looked to his left at Bonnie, a 7-year-old sorrel mare. He knows there’s something special flowing through her equine blood, and it’s the reason why he’s having a strong tie-down roping season. The two proved it together during the July 30 performance of Dodge City Roundup Rodeo. He roped and tied two calves in a cumulative time of 17.8 seconds and sits No. 2 in the aggregate race. That should be enough to secure his spot in Sunday’…