Jessies First Down, the world champion Quarter Horse of 2016, will launch his season in a Friday night trial at Sam Houston Race Park – and he’s not the lone world champion running on the meet’s first card. Jrc Callas First also will be in action, the world champion of 2014 set to get his season underway in the $20,000 Harris County Stakes.  Sam Houston’s meet for Quarter Horses will run 24 dates, through May 22. The track will race Friday and Saturday nights, and in the afternoons on Monday.  Jessies First Down goes in the seventh race, which is one of two trials on the card for the Grade 2, $95,000 Texas Challenge Championship at 440 yards April 22. Jessies First Down locked up Quarter Horse racing’s most significant title after winning three straight Grade 1 races to close out 2016 – the Refrigerator at Lone Star Park, the Zia Park Championship, and the Championship at Sunland on Dec. 31  Judd Kearl, a seven-time leading trainer at Sam Houston, conditions Jessies First Down for breeder Ted Abrams Sr. The horse will break from post 7 under Rodrigo Vallejo. The Harris County, which goes as the ninth, will be the first start since October for Jrc Callas First, who won last year’s Texas Challenge Championship over Jessies First Down. Trainer Brian Stroud told Sam Houston officials that after Friday night’s start in the 550-yard race, the horse could move to 870 yards, a “hook race,” or one that is run around one turn rather than just down the straightaway as with the majority of races for Quarter Horses.  Highlights of the stakes schedule include the Grade 2 Sam Houston Futurity on April 29 and the Grade 2 Sam Houston Classic on May 13.