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Test-tube joeys for Queensland koalas

The joeys were conceived using new breeding technology, which uses sperm mixed with a special solution that prolongs the sperm’s shelf-life.

Project leader, Dr Steve Johnston, senior lecturer and reproductive biologist at the School of Animal Sciences said koalas are not particularly endangered overall, but the 10-year project to develop artificial insemination was a form of insurance.

Steve&Arania
UQ’s Dr Steve Johnston and female joey Arania. (Photo courtesy Chris Stacey, The University of Queensland)

“We’re looking at actively managing their genetics,” he explained. “While in some parts of Victoria, and on Kangaroo Island in South Australia there are too many koalas, in others places – Queensland and parts of NSW, their habitat has been reduced or compromised, so there are often very small populations that need to be actively managed to protect their genetic diversity. The very small populations of koalas in zoos in Australia and overseas means their breeding also needs to be actively managed.”

The research is a joint project for UQ advanced reproductive technology scientists, Queensland Parks and Wildlife Service, Dreamworld, Currumbin Wildlife Sanctuary, David Fleay’s Wildlife Park and the Zoological Society of London. The koala project came about as an adjunct to a project to develop AI for the highly endangered Northern hairy-nosed wombat, of which there are only about 90 left.

“We decided to look at AI in koalas first, as there are so many more of them, so that initial failures wouldn’t be so disastrous,” Johnston said. Koalas are evolutionarily quite closely related to wombats.

Researching the koalas’ reproductive cycle proved to be serendipitous for the team, Johnston said. “We had to learn a lot about their basic biology to understand their reproduction, and this was work that hadn’t been done before.”

They learned that koalas – like cats – required mating to induce ovulation. However, unlike cats, the males’ semen also plays a role in ovulation, containing a chemical which actively assists ovulation. “In this way, we discovered that koalas are more like camels and alpacas than cats,” he said.

“Eight of the twelve current test-tube joeys were born following the artificial insemination of freshly diluted sperm samples,” Johnston said. Diluting the sperm allows them to be kept alive for transporting, but the team had to be sure the diluent didn’t reduce the efficacy of the sperm’s ovulating factor

The next vital step is the use of chilled sperm and then thawed frozen sperm from the sperm bank, before the sperm bank can be considered to be successful. Transporting sperm samples within Australia usually means the semen only needs to be kept alive for a day or two, but for overseas zoos and wildlife parks, they would need to be frozen to survive the several days’ travel. All sperm samples are routinely screened for Chlamydia and retroviruses that infect koalas.

Vets and marsupials

Dr Vere Nicolson from Dreamworld and Dr Michael Pyne from Currumbin Wildlife Sanctuary assisted with anaesthetising the males for sperm collection and with taking blood samples for checking the females’ progesterone levels. The females are tested for progesterone on Day 0 of their cycle – when they are on heat – and again at Day 28, to gauge the quality of the corpus luteum and the hormone concentration.

Like cats, koalas have two cycles – a short 30 day one if not mated, and if not pregnant, they come back onto heat after 50 days. Their total gestation period is 35 days, and they generally only bear one joey at a time.

The interest in marsupials is growing among vets. Every Australian wildlife park and zoo has at least one looking after marsupials, and Queensland Parks and Wildlife employs several. Vets in private practice are also taking more interest in treating marsupials, which they come across when people from organisations such as WIRES bring rescued or orphaned animals to them after road accidents or following bushfires. Johnston says it’s hard to gauge how much time is spent treating marsupials – kangaroos, wallabies, koalas – even wombats or echidnas, but he says it would add up to millions of dollars of pro bono work across the country.

Sex toys for koalas

Since little research had actually been done on the koala’s reproductive habits, Johnston said his team “had to watch what the boys did and mimic it” to develop a method of insemination. The female has two vaginae linked by a urogenital sinus, so a catheter similar to one used for cats is used to deposit the semen in the urogenital sinus.

However, from watching koalas mate, “quite vigorously” and knowing that the female needs the physical act of mating to stimulate ovulation, the team had to find a way of mimicking the physical action of mating. They came up with a glass rod with soft spikes on the end, which is rubbed against the female’s urogenital sinus, to relax her, and make her more receptive. In effect, a sex toy for koala females.

“The female relaxes – she seems to be enjoying it – and as the rod goes in further, the urogenital sinus dilates, and this allows the catheter to deposit the semen closer to the vaginae.” A relaxed female also obviates the need for anaesthetising for insemination.

Wombats and echidnas too

Johnston says he is “keen to have a go at assisted breeding for wombats”, and he predicts that this will be about 18 months away. With a team at Rockhampton Zoo he is studying the reproductive cycles of nine females and four males of the more common Southern hairy nosed wombat, in preparation for the big one – AI for the highly- endangered Northern hairy nosed wombat. “We need to work out the fundamentals, as we did with the koalas – observe them and adapt our technology. Wombats are not as easy to collect blood from as koalas, who are generally quite happy to put out their arms.”

He’s also looking at echidnas, working with short-beaked animals as a model before the rarer long-nosed species. Once again, Dr Johnston and his team will be breaking new ground, describing the reproductive life of one of Australia’s iconic animals.

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