Endocrinology Enhances Zoo Breeding Strategies

Reproductive physiologist Ja- nine L. Brown may say she’s a “lab geek” who “hides behind hormones,” but her groundbreaking work in endocrine monitoring at the Smithsonian Conservation Biology Institute in Front Royal, Virginia, reaches around the globe.

Her staff has trained re- searchers at China’s Panda Breeding Center, Chiang Mai University in Thai- land, and the Pinnawala Elephant Orphanage in Sri Lanka. Through the National Zoo’s Elephant Endocrine Diagnostic Laboratory, she monitors the reproductive health of zoo elephants through- out the United States, analyzing more than 7,000 serum samples per year to monitor reproductive cycles, schedule breeding, and determine reasons for infertility.

Joining the Smithson- ian in 1991, Brown, who has an M.S. and a Ph.D. in animal sciences, says her first 10 years were spent learning where different steroids are secreted— whether in urine or feces—in order to develop non-invasive hormone monitoring techniques. Steroid metabolism and routes of excretion can vary widely across species, so proper assay development is critical. Ultimately, 70 percent of her lab’s research involves fecal monitoring to assess fertility in just about any animal in captivity.

Brown recently assisted in timing the artificial insemination of the National Zoo’s female panda, Mei Xiang, whose chances of conceiving were rated at less than ten percent because she had already had five false pregnancies. Tragically, the cub born in August died a week later from liver and lung complications.

“Our endocrine lab lived and breathed panda hormones for five months,” says Brown. “We experi- enced immense elation at the birth, followed by intense heartbreak over the cub’s death.”

Studying daily urine samples, Brown and her staff had followed
14-year-old Mei Xiang’s estrogen conjugates as they rose. Once estro- gen levels peak and ovulation oc- curs, female pandas have a two- to three-day window to conceive. “As with most mammals, the egg is only viable for a short time,” Brown said, “so by monitoring the hormones the staff knows precisely when to conduct the inseminations.”

Artificial insemination (AI) is often done with captive pandas because natural mating attempts fail. “For some reason, males don’t position the female properly for breeding, so we need to step in and do AI,” Brown adds.

A very frustrating aspect of the process is not being able to tell whether or not a panda is pregnant, Brown says. “The estrogen and progesterone profiles are exactly the same for pregnant and pseudopregnant luteal phases, so we can’t know for sure [she is pregnant].” A panda fetus is very difficult to detect on ultrasound because it remains very small up until the last two weeks. “Even at birth a panda cub weighs less than a stick of butter,” Brown says, noting that “many births have oc- curred when ultrasound saw nothing.”

Because the cub’s death was not due to Mei Xiang’s health, Brown is confident she can yet conceive and de- liver successfully. “Are we up to trying again?” she wrote in an email. “You bet we are!”

Brown also monitored Mei Xiang’s hormones leading up to the conception and birth of her first cub, Tai Shan, in 2005. A very popu- lar zoo attraction for several years, he was sent to China in 2010 as part of an earlier agreement.

Brown’s career in animal fertil- ity, however, started with elephants. Regardless of the species, she begins with hormonal analyses to learn about their basic biology, like what is the length of their estrous cycle, whether reproduction is seasonal, and how to tell when females are pregnant.

“You figure all that out and then you’re better able to figure out reproductive problems in individual animals and develop treatments,” she says. “We rely heavily on en- docrinology to determine how well our hormonal therapies are working, including those used with AI.”

One of Brown’s most famous successful pregnancies was that of
Shanthi, the National Zoo’s Asian elephant. Brown and her staff began tracking the length of fol- licular and luteal phases in Shanthi in the 1990s to determine the most opportune time for artificial insemination.

“Identifying a unique hormone pattern in elephants, which involves two luteinizing hormone surges during the follicular phase, was key,” she says. The first surge begins within one to three weeks after the luteal phase ends, when progester- one levels drop to a base line. After another three weeks, the second surge occurs.

“We breed elephants based on finding the first surge, using daily blood samples and then schedule natural mating or artificial insemination three weeks later,” Brown explained. There are few experts in elephant ultrasound and artificial insemination and they need as much lead time as possible. Using the endocrine procedures developed by Brown’s staff is essential to getting the tim- ing right.

“This is routinely done now,” she says, “with ours being the primary lab for these services.”

Artificially inseminated using a revolutionary catheter technique developed in Germany, Shanthi gave birth to Kandula in 2001. He is one of three Asian elephants at the Na- tional Zoo in Washington, D.C.

Although endocrine monitoring is useful for timing fertility in zoos, farther afield it is essential in as- sessing the welfare of other captive
populations. Logging camps in Burma and ecotourism centers in Thailand rely on the use of captive elephants. These populations of elephants are extremely important, Brown says, be- cause habitat for the Asian elephant, an endangered species, shrinks yearly from human expansion.

“These may well end up being the only ones left until we can figure out how to preserve habitat.”

To help protect them, Brown is currently validating a technique to measure stress through cortisol lev- els in elephant hair so adjustments can be made to the work environ- ment of these labor populations.

Closer to home, she is one of nine researchers assessing the welfare of captive elephants in 70 zoos across the United States, Canada, and Mexico, measuring hormone levels associated with reproductive health, thyroid function, nutritional status, health, and stress. The resulting data will be critically important in understanding how current zoo man- agement affects elephant welfare.

Brown admits there is plenty left to learn. For 20 years, she has been studying ovarian acyclicity in captive African elephants, a major fertility problem that prevents the establishment of self-sustaining populations in zoos.

“I keep saying, as soon as I figure out how to fix acyclicity in African elephants, I can retire,” Brown says. “We have a whole list of things it’s not related to, but I still don’t know how to fix it. And at this rate I think I’ll never be able to retire.”

The zoos of the world might thank her.

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