I gather the commentators have never heard of ivf for humans. When you're dealing with endangered species there are world-wide data bases of DNA to ensure breeding is done to produce viable offspring that are not related and without passing on genetics known to produce deleterious effects. There is no "wild" any more; however there is good work being done to mitigate the damage to existing herds through anti-poaching and anti-trafficking efforts. The most successful programs work with locals and it becomes their interest to protect the animals. I'm certain you'd be surprised to know that zoo staff visit these places and assist on their time off, using their own resources.  The anti-captivity people need to visit modern zoos to learn what truly happens; start with the conservation pavilions.