Chapter 42.3, Problem 1CSR

Whether using artificial insemination or nature’s way, rhino breeders are most successful when they can time sperm transfer to coincide with ovulation The surest way to achieve this synchrony is to induce the female to ovulate when a male rhino or sperm sample is ready. As you have learned, ovulation in mammals is stimulated by a surge of LH and FSH. which in turn is simulated by a surge in GnRH. Ovulation in rhino cows can be induced by injecting the females with a synthetic version of GnRH.

The next step depends on how the cow will be fertilized. For normal mating, the biologists wait until the female shows signs of mating interest. The male and female are then housed together and watched carefully for signs of mating or aggression. For artificial insemination, the biologists use ultrasound to check for the presence of ripe follicles Semen collected from a bull rhino is then inserted into the cow’s uterus. For IVF. the biologists suck ripe eggs out of the cow's ovary. again using ultrasound to guide their efforts, mix the eggs with sperm, and implant the resulting embryos into the cow s uterus.

These procedures have all proven successful. White, black, Indian, and Sumatran rhinos have been successfully bred using one or more of these techniques. With highly endangered species like the Sumatran. Javan, and black rhinos, preserving genetic diversity is extremely mportant. which means that every male and female should be given the chance to pass on their genes by reproducing with rhinos around the world. Artificial insemination using frozen sperm is much safer and less expensive than shipping rhinos between zoos. Artificial insemination can even help to preserve the genes of deceased bull rhinos. Tashi. the Indian rhino cow at the Buffalo Zoo. was artificially inseminated with sperm from Jimmy, a rhino bull who died at the Cincinnati Zoo about 10 years earlier. Jimmy's sperm had been stored all that time, frozen in liquid nitrogen. The Buffalo Zoo named the calf Monica, after Dr. Monica Stoops of the Cincinnati Zoo. who performed the artificial insemination (see the chapter opener photo).

Similar techniques have also been used with other endangered species For example, at the Smithsonian National Zoo in Washington. D.C.. black-footed ferrets were born whose fathers had died almost a decade earlier. In addition to the Cincinnati Zoo. several other facilities including the Audubon Nature Institute and the San Diego Zoo. maintain Frozen Zoos—liquid nitrogen storage tanks containing frozen sperm, tissue samples, and even embryos tom endangered species.

By rhino standards, southern white rhinos are abundant—there are about 20,000 of them. In contrast, there are fewer than 50 Javan rhinos and 100 Sumatran rhinos in the world. How might white rhinos be used to increase reproduction of Javan and Sumatran rhinos? Describe advantages and obstacles to you proposals.