The racing mule Idaho Gem, the world’s first equine clone, made a favorable impression in his initial start on the California fair circuit, striding away to a 2 1/2-length win in a 350-yard allowance event at Stockton Wednesday.

The same could not be said for Idaho Star, the winner’s long-eared genetic twin. Idaho Star shied from the rope pony as he was being guided toward the starting gate, lost rider Bernie Santos, and took off. He had to be scratched, holding up the start of the race for more than five minutes.

The 3-year-old Idaho Gem, who runs in the colors of Donald Jacklin for trainer Ruby Thomas, picked up his second win in three starts. With Carlos Villalobos riding him for the first time, Idaho Gem broke second best but soon took control, veered in a little after clearing off by two lengths, and maintained his advantage under the wire to score at odds of 6-5 against five conventional mules. The 9-10 favorite, Bar JF Rock On, ran second, 4 3/4 lengths ahead of Classy Recruit, who was the early leader. The time, :20.92, was faster than the 4-year-old mule Ghenghis Khan ran in winning the preceding race and was the quickest clocking turned in by a 3-year-old this season. Ghengis Khan was the champion 3-year-old mule of 2005.

“I’m just really thrilled,” Jacklin said. “Ruby was ecstatic. The jockey didn’t have to raise his stick, and he ran a straight line