@Buldeo, if any breeding with elephants is planned they should plan for another adult bull and one which is significantly older than "Osh" and a more dominant (and thus able to confront the harem herd and do the business) one to that.
BTW: Bull Osh is now 22 years of age, so very close to the 22-25 time frame where-upon wild bulls become sexually operative / dominant and hold territory in nature / wilds.
Not sure though, if the former complaint may still exist. However, there is a real question-mark over the females - as much older than bull Osh - that when they are yet non-primiparous are unlikely to breed at all as reproductive senescence kicks in after the age 20-25 with non-breeding female elephants.
A check on the Oakland Zoo pages for their elephant herd comes up with this info:
F M’Dundamella (estimated age - YoB 1969, arrived 12/1993)
F Donna (estimated age - YoB 1979, arrived ??)
F Lisa (estimated age - YoB 1977, arrived ??)
M Osh (born 1994, arrived ??)
LINK:
African Elephant
Hence, one may conclude breeding from this group is a dead end / show stopper, I am afraid.