That’s the million dollar question. In the 2005 annual report, Perth Zoo documented a mating between him and Permai; but no calf resulted and they switched to AI after natural breeding was unsuccessful.
Two decade later, he’s had no further opportunity to practice natural mating, so it’s really anyone’s guess. What I would say though, is Pak Boon (a twice proven natural breeder) at least knows how to stand for a bull. If he can’t successfully mount her, I doubt he’d succeed with any cow.
Perth Zoo’s 2005 annual report:
During the year, Perth Zoo recorded the first known natural mating of elephants in an Australian zoo. The mating followed the carefully planned pairing of 16-year-old male Putra Mas and 16-year-old female Permai as part of the Zoo’s breeding program for the endangered Asian Elephant. The pairing was timed to coincide with Permai’s reproductive cycle. Subsequent blood analysis revealed that Permai was not pregnant.