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Zoo uses fitness tracker to help endangered cattle

Scientists hope data will boost breeding efforts of banteng

By Gabe Barnard, St. Louis Post-Dispatch
Published: August 26, 2022, 6:16am
3 Photos
To research how physical activity changes during fertility in bantengs, workers at the St. Louis Zoo have put fitness trackers on the back ankles of two of the female bantengs. The front ankle has a colored tag to differentiate between the two, one wearing pink and the other wearing blue. (Photos by Allie Schallert/St.
To research how physical activity changes during fertility in bantengs, workers at the St. Louis Zoo have put fitness trackers on the back ankles of two of the female bantengs. The front ankle has a colored tag to differentiate between the two, one wearing pink and the other wearing blue. (Photos by Allie Schallert/St. Louis Post-Dispatch) Photo Gallery

ST. LOUIS — Poaching and habitat loss are driving a species of exotic cattle toward 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 breeding efforts. The discovery arrives as the zoo forges ahead with plans for its WildCare Park, which is designed partly to help scientists conserve endangered species, and builds on years of zoo work aimed at restoring threatened animal populations.

“It’s like a jigsaw puzzle in a sense,” said Karen Bauman, the zoo’s manager of reproductive sciences. “Each little piece of scientific data helps us make a better, completed picture for conservation.”

The current picture isn’t pretty.

There are likely fewer than 5,000 banteng left in the wild in their native Southeast Asia, including Indonesia, Cambodia and Myanmar. That’s a 95 percent decrease in their population from the 1960s, according to the Asian Wild Cattle Specialist Group. Poachers hunt the elusive cattle for its meat and horns, and human expansion has fragmented their habitat and isolated remaining populations.

Zoos around the world have been building 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.

The key to zoos’ conservation efforts is a big family tree of genetic information called a studbook. It shows how individual banteng are related to each other, how many calves they’ve given birth to and where they’re from geographically. Keepers use the book as a matchmaking guide to bring together the most diverse pairs of banteng to, hopefully, reproduce.

That’s important because the 42 banteng in U.S. zoos are all descended from a small group of cattle imported to the U.S. Keepers must carefully choose which banteng they match to minimize inbreeding, which can put the animals at higher risk of disease and death.

But once chosen, the male and female banteng don’t have to be physically together. Instead, zoos may use artificial insemination, placing frozen sperm in a cow’s uterus. That removes the hassle of transporting a 1,000-pound banteng between zoos.

“I can FedEx a semen sample and get it there tomorrow,” Bauman said. “I can’t FedEx a cow.”

Artificial insemination is a tool with huge potential, said Dallas Zoo large mammal curator Steve Metzler, who manages the international banteng studbook. It’s helped efforts to conserve other endangered species, such as the Mexican gray wolf and black-footed ferret.

“It’s a way of connecting or having genetic flow between populations without actually physically having to move an animal between those populations,” Metzler said.

But it’s 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 named McGwire, after former Cardinals first baseman Mark McGwire, and scientists thought they had 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 have it all figured out. In the years since, female banteng have lost their calves in 30 percent to 50 percent of pregnancies attempted by artificial insemination at the zoo, Bauman estimated.

Scientists weren’t sure what was causing the pregnancies to fail. One hypothesis was that stress could be stopping the cows’ reproductive cycles, Bauman said. To measure that, they’d need to take samples of a banteng’s hormones, the chemical messengers that send signals throughout the body.

But many other factors can also influence a cow’s reproductive cycle, including age and breeding history. The bottom line was that the scientists needed to dive deeper.

“We need to better understand some really subtle, important details about what happens in the cow,” Bauman said.

The scientists tapped one tool in particular that had already been important in studies of other animals: activity sensors.

It had long been established that female animals, including domestic cattle, change their activity when at their most fertile. Bauman knew fitness trackers would be useful for studying whether that was the case in banteng.

University of Missouri animal scientists, who had collaborated with the zoo before, loaned a few of their sensors, made by Scotland-based IceRobotics.

Researchers strapped the trackers to the bantengs’ ankles. They monitored how many steps the cows took, how often they laid down and how often they stood, combining the data into an overall score of movement.

At the same time, scientists extracted hormones from banteng stool samples. They tracked progesterone, a hormone produced by ovaries that increases when a female is most fertile or pregnant.

“If she’s pregnant, her progesterone is going to go up to stay up. If she’s not cycling at all she’s going to be flatlined,” said Corinne Kozlowski, an endocrinologist at the St. Louis Zoo and co-leader of the research with Bauman.

Scientists graphed the results, and what they saw had never been described before: Female banteng were both most fertile and most active in the summer, meaning the species might have seasonal changes in fertility. If the zoo were to attempt another artificial insemination, Bauman said, workers could time it to when they now know the female is most fertile.

Bauman said their discovery is pivotal to fine-tuning the timing of artificial insemination. It could be helpful for transferring genes between captive and wild populations globally with more successful pregnancies. Frozen sperm from a banteng bull could be used to artificially inseminate a cow caught from the wild and placed in a sanctuary, she said.

Or vice versa. Metzler said another potential application of the discovery is to transport genes from wild populations of banteng, which are more genetically diverse, into U.S. zoos, where the small population is becoming increasingly inbred.

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The researchers are planning to publish their results in the academic journal, Animal Reproduction Science.

But there’s still a ways to go. For starters, some countries currently prohibit zoos from transporting semen for artificial insemination, Metzler said.

And getting frozen sperm across the globe is only the first hurdle.

Experts said capturing wild banteng could cause heavy stress, ending any chance of a successful pregnancy.

Nick Marx, director of wildlife rescue and care for the Wildlife Alliance, said the best method would be to protect the wild habitat banteng need to breed naturally.

Bauman said the big picture is that artificial insemination is a small step toward solving to the banteng’s other conservation needs — but it could be one important tool of many to help improve populations.

“We need to sort of walk before we can fly,” she said.