I am pretty sure the reasons why Melbourne and Taronga have stopped elephant breeding are:
1. They are afraid to produce more bull calves and dont know what to do with them once they grow up.
2. They need AI to get their females pregnant and that is incredibly expensive and overall a huge effort. Remember that the vets to perform the procedure must be flown in from overseas. The elephants need extensive training, daily blood tests, and all needs to be coordinated with perfect timing: vets from overseas, fresh semen in good quality from the bull, blood tests. If just one thing goes wrong its over for the next couple of months but the costs must still be paid. And it can take serveral tries before the female is expecting. No zoo in the world has ever managed to archive natural birth rates through AI. Its just too much work and too expensive. The lack of calves in Australia is the norm and not the exeption when zoos rely on AI.
1. They are afraid to produce more bull calves and dont know what to do with them once they grow up.
2. They need AI to get their females pregnant and that is incredibly expensive and overall a huge effort. Remember that the vets to perform the procedure must be flown in from overseas. The elephants need extensive training, daily blood tests, and all needs to be coordinated with perfect timing: vets from overseas, fresh semen in good quality from the bull, blood tests. If just one thing goes wrong its over for the next couple of months but the costs must still be paid. And it can take serveral tries before the female is expecting. No zoo in the world has ever managed to archive natural birth rates through AI. Its just too much work and too expensive. The lack of calves in Australia is the norm and not the exeption when zoos rely on AI.