ST. LOUIS — Poaching and habitat loss are driving an exotic livestock species to extinction in the wild.
But scientists at the St. Louis Zoo are coming to the rescue — with fitness trackers.
Researchers there used the bovine version of a Fitbit, combined with fecal samples, to uncover hidden patterns in the animals’ reproductive cycles.
The results could be key to protecting the animals, called banteng, and scientists hope the data will boost the success of the breeding efforts. The discovery comes as the zoo plans for its WildCare Park, which is designed in part to help scientists conserve endangered species, and builds on years of zoo work aimed at restoring endangered animal populations.
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“It’s a puzzle in a way,” said Karen Bauman, the zoo’s reproductive sciences manager. “Every little piece of scientific data helps us create a better, finished picture for conservation.”
The current photo is not pretty.
There are probably fewer than 5,000 Banteng in the wild in their native Southeast Asia, which includes Indonesia, Cambodia and Myanmar. That’s a 95% decrease in their population since the 1960s, according to the Asian Wild Cattle Specialist Group. Poachers prey on the elusive livestock for its meat and horns, and human expansion has fragmented their habitat and isolated the remaining populations.
Zoos around the world have set up a backup plan by growing a captive population as a bulwark against extinction. The St. Louis Zoo is home to four female and one male Banteng.
‘I Can’t Cow FedEx’
Key to zoo conservation efforts is a large family tree of genetic information called a studbook. It shows how individual Banteng are related to each other, how many calves they have borne and where they come from geographically. Keepers use the book as a matchmaking guide to bring the most diverse pairs of banteng together to, hopefully, reproduce.
That’s important because the 42 banteng in US zoos are all descended from a small group of cattle imported to the US. Keepers must choose which banteng to match carefully to minimize inbreeding, which puts the animals at greater risk of illness and death.
But once chosen, the male and female banteng do not need to be physically together. Instead, zoos can use artificial insemination, in which frozen sperm is placed in a cow’s uterus. That eliminates the hassle of transporting a 1,000-pound banteng between zoos.
“I can get FedEx a semen sample and deliver it there tomorrow,” Bauman said. “I Can’t Cow FedEx.”
Artificial insemination is a tool with enormous potential, says Steve Metzler, curator of large mammals at Dallas Zoo, who manages the International Banteng Stud Book. It has contributed to the conservation of other endangered species such as the Mexican gray wolf and the black-footed ferret.
“It’s a way of bringing populations into contact with each other or genetically progressing without having to physically move an animal between those populations,” Metzler said.
But it is not yet a reliable technique in Banteng.
In 1998, a Banteng cow in St. Louis gave birth to the first calf produced by artificial insemination. It was called McGwire, after former Cardinals first baseman Mark McGwire, and scientists thought they hit a home run.
“We did the (artificial insemination) and we were successful and we were like, ‘Yay us!’ and then we moved on,” Bauman said.
They didn’t quite get it all. In the years since, female Banteng have lost their calves in 30% to 50% of pregnancies attempted through artificial insemination at the zoo, Bauman estimates.
Scientists weren’t sure what caused the pregnancies to fail. One hypothesis was that stress could halt the cows’ reproductive cycles, Bauman said. To measure that, they would need to take samples of a banteng’s hormones, the chemical messengers that send signals through the body.
But there are also many other factors that can influence a cow’s reproductive cycle, including age and breeding history. The bottom line was that the scientists had to dive deeper.
“We need to better understand some really subtle, important details about what’s going on inside the cow,” Bauman said.
In particular, the scientists tapped into one tool that was already important in studies with other animals: activity sensors.
It has long been known that female animals, including domestic cattle, change activity when they are most fertile. Bauman knew that fitness trackers would be useful to investigate whether that was the case in Banteng.
University of Missouri animal scientists, who had previously worked with the zoo, borrowed some of their sensors, made by Scotland-based IceRobotics.
Researchers tied the trackers to the ankles of the bantengs. They tracked how many steps the cows took, how often they lay down and how often they stood, and combined the data into an overall exercise score.
At the same time, scientists are extracting hormones from samples of banteng stool. They tracked progesterone, a hormone produced by ovaries that increases when a woman is most fertile or pregnant.
“When she’s pregnant, her progesterone goes up to stay upright. If she doesn’t cycle at all, she gets squashed,” said Corinne Kozlowski, an endocrinologist at the St. Louis Zoo and co-leader of the study with Bauman.
Scientists graphed the results and what they saw had never been described before: Female Banteng was both most fertile and most active in the summer, meaning the species may have seasonal changes in fertility. If the zoo tried another artificial insemination, Bauman said, workers could time it until when they now know the female is most fertile.
Bauman said their discovery is crucial in refining the timing of artificial insemination. It may be useful for gene transfer between captive and wild populations worldwide with more successful pregnancies. Frozen semen from a Banteng bull could be used to artificially inseminate a wild-caught cow and place it in a shelter, she said.
Or vice versa. Metzler said another possible application of the discovery is to transport genes from wild populations of Banteng, which are more genetically diverse, to U.S. zoos, where the small population is becoming increasingly inbred.
The researchers plan to publish their results in the scientific journal Animal Reproduction Science.
But there is still a way to go. For starters, some countries currently prohibit zoos from transporting sperm for artificial insemination, Metzler said.
And getting frozen sperm around the world is just the first hurdle.
Experts said that catching wild banteng can cause severe stress, ending any chance of a successful pregnancy.
Nick Marx, wildlife rescue and care director for the Wildlife Alliance, said the best approach would be to protect the wild habitat that banteng needs to breed naturally.
Bauman said the big picture is that artificial insemination is a small step toward solving the banteng’s other conservation needs — but it could be an important tool to help improve populations.
“We have to walk a bit before we can fly,” she said.