How is this work different from work done in domestic horses?
The domestic horse has been studied systematically for decades leading to routine use of assisted reproductive technologies such as artificial insemination, sperm cryopreservation, and embryo transfers. Despite these advances, little effort has been invested in the study of wild equids.
Recently, we reported the successful birth of two foals in the Persian onager via artificial insemination. This was a landmark event since no other wild equid has been born via artificial insemination. Although it is reasonable to assume that the reproductive systems of domestic mares would be similar to that of Przewalski’s mares, our past experiences suggest otherwise. We needed to understand the basic reproductive biology of the Przewalski’s horse.
Przewalski’s horses have kept retained all of their wild instincts and can be challenging to work with them. To date, no one has successfully put a halter on a Przewalski’s horse. Unlike with domestic mares, we cannot command the animals to cooperate with researchers and managers.
Our work is more about the basics than the intricate work being done with domestic horses. We are interested in taking the techniques and practices developed for domestic horses and applying them to this endangered species. One example of this is the utilization of artificial insemination. A technique regularly used with domestic horses—the successful application of artificial insemination in Przewalski’s horse—would open up many new opportunities for genetic management. These advances in the Przewalski’s horse also would enable the safe and efficient transportation of frozen sperm instead of live animals for breeding purposes. We are constantly striving for the betterment and preservation of this endangered species in captivity.
Anne and fillyt. Photo by Dolores Reed, NZP
Anne's filly is doing wonderfully. She cut her first tooth last week!
A second Przewalski's horse foal was born on August 15 to a mare named Solongo (which means "rainbow" in Mongolian). The foal is a little colt born not from artificial insemination but from natural breeding. A Stallion named Frog is the colt’s father. Frog is also the grandfather of the AI filly (he is Anne’s dad). Frog is the most genetically valuable Przewalski's horse in North America.
Solongo's colt. Photo by Dolores Reed, NZP
As the little filly is now more than three weeks old, she was really wanting someone to play with. In the wild, foals are born relatively close together in the spring and summer.
Animal care staff introduced on August 20, and everyone seems to get along, though they haven’t interacted much yet. The moms are keeping the youngsters close at their sides so far. It may take a few days for them to get acquainted.
Anne and her filly are on the right, Solong and her colt are on the left.
Photo by Dolores Reed, NZP
Why work with wild equids? What is special about Przewalski's Horse?
When they hear the word "horse" most people have a distinct mental image of the domestic horse (Equus ferus caballus) we loved as children—who didn’t want a pony as a kid? The domestic horse has become a multi-million dollar industry to some and serves as companion animals to others. We have a vast and intimate understanding of them, from nutrition to reproduction, exercise physiology to social structure and herd dynamics.
However, the domestic horse is not the only equine species in existence. Seven equid species survive today in various regions of the world, but most people only recognize the zebra (there are three species of zebra alone). Few are familiar with other equids including the Persian onager or Somali wild ass or the Khulan. In contrast, the Przewalski’s horse is considered the last wild horse although it is often mistaken for a breed of domestic horse, the Norwegian Fjord.
Despite our extensive knowledge about domestic horses, scientists know relatively little about wild equids. Although we have ideas and comparisons we can make from our experience with E. caballus, we are finding that these are not entirely parallel. Given the changing landscapes and increasing uncertainty of wildlife habitat, we need to understand and uncover all that we can about wild equids to ensure their survival both in the wild and in captivity.
For example, the typical social structure of the horse is a harem, wherein a single stallion leads a group of mares to form a herd. This is our traditional view of a herd of horses. However, the Khulan (Asian wild ass) forms fusion/fission groups, a far more loose social structure that comprises multiple stallions in a herd. The herd is also less stable group, allowing entry and exit of new animals on a regular basis, compared to a typical herd.
Four of the six wild equid species are endangered or critically endangered, thus genetic management is also a crucial part of managing these species successfully in captivity. The concept of insurance populations managed in captivity is extremely important when considering the fragile future of these wild equids.
There is hope, though. Przewalski’s horses were extinct in the wild in 1969, but animals in European zoos were bred to grow the population and were reintroduced in nature reserves in Mongolia in 1993. The Przewalski’s horse also was recently re-classified from critically endangered to endangered. They are one of the success stories of an endangered species. After their extinction in the wild, there were only 14 breeding adults–the entire population is therefore descendants of these 14 animals.
The Przewalski’s horse can breed and give birth to fertile offspring with domestic horses. This is peculiar due to the differing number of chromosomes: domestics have 64 while Przewalski’s have 66 and the hybrid (65 chromosomes) remain fertile unlike the horse and donkey hybrids. As with many of the wild equids, they share many similarities to the domestic horse, but significant differences as well.
Ultimately, the goal of equid research at SCBI is to better understand the fundamental biology of rare and endangered equids and to use this new information to establish self-sustaining populations both in captivity and in the wild.
Scientists at the Smithsonian Conservation Biology Institute are celebrating the birth of a female Przewalski’s (Cha-VAL-skee) horse—the first to be born via artificial insemination. The foal’s birth on July 27 signals a huge breakthrough for the survival of this species. SCBI reproductive physiologist Budhan Pukazhenthi and the Przewalski’s horse husbandry team spent seven years working closely with experts at The Wilds and Auburn University in Alabama to perfect the technique of assisted breeding. Both the filly and the first-time mother Anne are in good health and bonding.
“It seems reasonable to assume that reproduction for the Przewalski’s horse would be similar to domestic horses, but it simply isn’t the case,” said Pukazhenthi. “After all these years of persevering, I can honestly say I was elated to receive the call informing me that the foal had been born. I couldn’t wait to see her! This is a major accomplishment, and we hope our success will stimulate more interest in studying and conserving endangered equids around the world.”
Anne was born at SCBI and is the daughter of a mare imported from Europe and the most genetically valuable stallion in the U.S. The filly’s father Agi also lives at SCBI. The Przewalski’s horse is considered the last wild horse on the planet, although it is often mistaken for a breed of domestic horse, the Norwegian Fjord. Little is known about wild equids despite the extensive knowledge of domestic horses, Equus caballus.
The usefulness of artificial insemination is that it does not require both animals to be together for a successful mating.The transport of animals to different locations can be difficult, dangerous, costly and potentially stressful to the individual. By contrast, the collection of semen can be safely accomplished under the supervision of veterinary staff and significantly improves the efficiency of managing small populations of endangered species. The birth of Anne and Agi’s filly required hormonal treatments for inducing ovulation in a mare, specialized animal-handling facilities, conditioning Anne to provide urine samples for hormone monitoring and routine ultrasounds. This accomplishment validates the importance of integrating animal management in the research and development of assisted reproductive technologies for endangered species.
Using ultrasound technology, Pukazhenthi confirmed the pregnancy about 35 days after the insemination. The mare’s pregnancy was monitored closely for 11 months measuring urinary hormone levels and visual keys (such as her growing belly).
“Anne is a young, first-time mother,” said Dolores Reed, supervisory biologist at SCBI. “She had a normal pregnancy that lasted 340 days and the foaling lasted less than 10 minutes. I’ve raised a lot of foals and other hoofed stock over the years, but this filly feels like an extra-special triumph for us and her species.”
This work is part of SCBI, The Wilds’s and Auburn University’scollaboration with the Conservation Centers for Species Survival, a group of large conservation facilities in North America dedicated to cooperative breeding and research for the advancement of species conservation. Established in 2005, C2S2 applies its unique resources for the survival of species with special needs, especially those requiring large living areas, natural group sizes, minimal public disturbance and scientific research. SCBI and The Wilds are members of C2S2, along with Fossil Rim Wildlife Center, White Oak Conservation, San Diego Zoo Global and Omaha’s Henry Doorly Zoo.
In 2008, veterinarians at the Zoo, in cooperation with a human fertility expert from St. Louis, performed the first successful vasectomy reversal on a Przewalski’s horse. This was the first procedure of its kind to be performed on an endangered equid species. SCBI scientists were also the first to produce two Persian onager foals via artificial insemination, a landmark event since no other wild equid had been produced via artificial insemination to date.
The Przewalski’s horse is a species native to China and Mongolia that was declared extinct in the wild in 1969. Today, approximately 1,500 Przewalski’s horses reside at zoological institutions worldwide, carrying genes from only 14 original animals. Due to hunting, harsh climate, loss of habitat and loss of water sources, fewer than 500 of this species are left in the wild. Currently, most live in Mongolia, China and Kazakhstan. SCBI scientists are working in remote areas of China using radio collars and Geographic Information System technology to map the movements of these horses, which were reintroduced by Chinese colleagues into their former habitat. Committed to preserving this species and equid research in general, SCBI works to maintain breeding populations that serve as a source of animals for reintroduction.