To Breed Or Not To Breed: The Role Of Artificial Insemination In Conservation
By Vickie O’Neil and Kay Neubauer, Saint Louis Zoo Docents
Artificial insemination and contraception, are two concepts that seem at opposite ends of the spectrum. How can we need both of these elements in conservation today? One to aid in reproduction and one to foil reproduction! Hopefully by the end of this session today, we can prove the need for each of them.
How have zoos changed over the years? Curators, Naturalists, and zoo administrations have made great strides in how zoos are run and what is important. When I grew up here in St. Louis and went to the zoo, it seemingly was all entertainment and fun. The animals were there for our enjoyment. There were elephant shows, chimpanzee shows and sea lion shows. These were done with tools to control the animals and make them perform for us. This is no longer a part of the zoo. Today the zoo is about the animals and not just pleasing the visitors. While it is still fun (and always will be) to go to the zoo, today’s number one job is the animals and all that concerns their future. Zoos are conservation today! Animals are number one. (We still have the sea lion show, but that is done with treats and praise.)
So, the number one job is conservation. Conservation is so important that the AZA heads the efforts of saving and reproducing endangered species in institutions nation wide. This is done with captive animal population controls. To most people, conservation efforts seem to be mainly done in exotic places, saving endangered species. While conservation is happening around the world, we do the majority of work in the zoos across the world. Without the zoo programs, these world wide conservation efforts would not survive.
Unfortunately, the zoos are the places where the future of some of these animals will be decided and hopefully be secured. Without our help and intervention, we will loose these endangered species. How sad it would be to lose so many more of these magnificent creatures. Plus when we loose one species, we all know about the ripple effect it has in the natural balance of things in our wild kingdom.
Not too many years ago, zoos could loose an animal and then replace that animal from the wild stock around the world. Sadly, today that is seldom the case. The animals are just not out there and if they are, they are very protected by their governments. You all know the reasons why our wildlife is endangered. Just a few of them are: loss of habitat, poaching, illegal animal trade, and bush meat. We are trying to build up supply with the breeding animals in captive populations around the world. Most of today’s zoo animals are captive bred and exchanged within the AZA institutions. Very few today come from the wild.
Keeping the animals of captive bred institutions healthy and strong with good genetic lines is done with careful consideration. Breeding is done under the guidelines and recommendations of the AZA and the programs they have established such as: The Species Survival Plan (SSP), and the Population Management Plan (PMP). This is how a certain female and a certain male are recommended to breed. A very big job considering all the different species. Today’s SSP and PMP are the e-Harmony.com of the zoo world. Recommended breeding animals are matched by their history and genetic background.
Seems like it would be so simple to put two animals together and let nature take its course. This is the old fashioned, tried and true mating. This still does occur. If you are lucky enough to have two animals recommended to breed, they are able to reproduce, they like each other and they are successful, you have just hit the jackpot. We are fortunate to have had our share of these over the last couple of years. We have successfully bred our Asian elephants, cheetahs, takins, camels, okapi, tree kangaroo, king penguin, and sifaka’s.
What happens when the two animals cannot get together? This is where science comes into play and we use Artificial Insemination. This is the artificial introduction of sperm from a recommended male into the reproductive tract of the recommended female at the optimum time to impregnate her. Our Endangered Species Research Center is staffed with scientists such as an endocrinologist, pathologist, lab techs, and veterinarian staff and students, that concentrate on reproduction. With their knowledge and abilities, we are able to provide help and information to institutions around the world.
Two animals recommended to breed, the male is at one zoo and the female is at another. They cannot get together. This could be for a variety of reasons. It could be that they are too big to be easily transported. A Hippo would be a good example. It could be that it is cost prohibitive to transport these animals. Zoos, like every one else, work on a budget and there is just not extra money. A big factor is the safety. It is always very dangerous to sedate or anesthetize these animals for transfer. Animals have been lost in these transfers. These animals are always high on the AZA breeder list, very valuable and sometimes irreplaceable. It may just be too much of a risk to transfer. And then there is always the “She doesn’t like him or he doesn’t like her” factor.
They may ignore each other or worse, attack one another. They just don’t click. This is where AI comes into play.
When a male animal is picked as the donor for artificial insemination, they have to be tested. What are we looking for? He’s got to be more than just a good looking guy, he has to be what we call a capable donor.
What does he look like? Is he physically a good healthy specimen? Is he able to reproduce? What is his testosterone level? What about his sperm? These are all questions that have to be answered. How do we go about collecting semen specimens? Not as easy as in humans. After all, we can’t send him into the other room with a magazine and a cup. How would you collect semen from a big cat, wolf, and large bird? There are times that we can collect the sample using very creative methods. (Such as this method used with this domestic bull mounting this specially rigged truck.) But these creative methods don’t work with exotic animals so we have specialized equipment called an electro ejaculator. This was originally designed for use in humans. When we use the electro ejaculator, the animal is anesthetized. (Our Bantang bulls will go into a restraint shute for this.) You need a veterinarian to monitor this procedure. Anesthesia is almost always the most challenging part of any procedure.
Once the specimen is collected, it has to be tested. They have to test the sperm for the same qualities that they check for in humans. Concentration, are there adequate numbers of them? Motility, are they good swimmers? Morphology, are they normal? We need to know that they are good to go.
When all looks OK, the sperm is prepared for freezing. They are protected with an extender. This keeps the sperm from being destroyed by ice crystals. The semen extender is made from chemicals you have probably never heard of like Trizma Base. However, some very common things can also be used as an extender such as egg yolk and skim milk!
Semen is either frozen in straws or as pellets. There are advantages and disadvantages to both. The straws are used about 95% of the time. It is easier to use the straws because they are a measured dose, one straw per insemination, easy to freeze and easy to thaw. It usually takes 2 pellets per insemination, they are more difficult to thaw.
To store the semen, we freeze the straws and pellets in a storage tank in our Cryobiology lab. They are maintained with liquid nitrogen at a -176 c. This ability to save semen like this is a huge asset to conservation.
There are animals who are no longer alive and their sperm is frozen in a pellet or straw for future use, thus assuring that their genes will move forward.
Thawing is as important as freezing. They have to be thawed just as they are being used. Straws are easiest to thaw. It takes only 5 seconds in a 37 degree c water bath immediately prior to use. The pellets must be thawed in some clear extender. Not water, as there is no outer coating like there is with the straws. This means you use a very small amount of additional liquid as it dilutes the sperm and this must also be done immediately prior to use.
If we are sending the semen samples to another institution, it is shipped in a portable liquid nitrogen tank and usually goes Fed Ex. If necessary, a staff member will also go along.
Once the female is recommended to breed with this particular male, they begin to study her. The first thing they have to find out is her reproductive cycle. This is done by tracking her hormones (estrogen and progesterone).
Each species has a different cycle. Think about all the various species we work with. Compare the cycle of an elephant, zebra, large bird, or big cat, all are very different time frames. The endocrinologist will track her hormones and chart her cycle.
How do they track her hormones? They have to have samples from the female to test. What do they test? Well, they can use blood, urine, fecal matter (stool or poop) and even sputum. Which sample do you think they use most often? Poop! And why would that be? Well it is readily available and easy to collect. Urine is harder to collect and not used as frequently. Think about collecting urine from animals. Other than following them around their enclosure, you can’t catch it. The exception is our elephants. Since they urinate in such large amounts, the staff made a catch pole that could reach through the bars and collect some urine. A catheterized specimen requires anesthesia. Blood can be easy or hard to collect, depending on the animals. Some are trained to present for blood draws, others have to anesthetized. What is hard is when they have to anesthetize the animal before they can draw blood. This makes it very difficult to get good reproductive cycle information because we would need to anesthetize the animal 3-5 times a week. So you can understand why stool is used most frequently. It does take more time to set up to test as it has to be turned from solid into liquid.
What do we do with the samples we collect? We have an endocrinologist, and an endocrinology lab that prepares the samples for testing. We use a machine called a Gamma Counter. It uses a radioactive reagent and a bonding test tube. We are very fortunate to have the staff and the machine and we do offer this service to other institutions. We can run 1 test or 100 tests. Obviously cheaper to run 100 tests and a time ($3 per test) as opposed to 1 test ($30). We do hold samples if they are not needed right away and run them when we have a full tray. We store samples until ready to use in a freezer in the lab.
With the readings we get from this test, a graph is charted out that shows the females reproductive cycle. Therefore we know when she is fertile and able to be impregnated.
When all is complete, the date and time are set for the insemination. People doing the procedure need to be trained and know how to use the equipment. Just like the semen collection equipment, the equipment used for AI varies by species. The female is anesthetized and the insemination is performed. At times our staff will go elsewhere to train people to do AI’s.
As you can see, this is a complicated and precise procedure. We have had some great success with the Mexican Grey Wolf. They are not at our zoo but at the Wild Canid Survival and Research Center here in the area. They are very endangered and need help to survive. We had at the time, a female that was at the top of the AZA breeding list. We also had a male that was very high on the list. So the SSP recommended they be put together for breeding. Unfortunately she did not like him and was aggressive towards him. They did mate however, and she had a litter of pups. She delivered them away from any help and did not nurse them. She was a very picky female but she did finally find a male that she liked. He was older and not on the SSP breeding list. So the scientists were called in to use the sperm from the high ranking breeder wolf to AI her. Luckily the AI worked and she had a litter of three pups. And with these she was a wonderful mother. She was with the older male during the AI so we had to use DNA to prove that the recommended breeder was the father. Because of the science and knowledge that we have, we were able to produce the pups with the genetic lines that we wanted. This is a good example of why and how we use AI.
Let me open the animal contraception section of our paper by asking a simple question. Fact or fiction: Animals are endangered because they do not breed well in the wild or in captivity? Fiction is the correct answer. No species is endangered because it does not reproduce well. In fact, most species reproduce very well in both captive management facilities and the wild.
More often human activity is the cause for animal population decreases and eventual endangerment. Territory encroachment, causing habitat loss and fragmentation, is a huge problem. Of course there are other human factors involved such as poaching and the introduction of plant and/or animal species that play havoc with many of the animals’ native habitats. Global warming, or to be more politically correct climate change, will no doubt become a major cause of endangerment and even extinction in the future.
In order to help balance harmful environmental problems, careful captive animal reproductive management is required. A provocative phrase, but what does it really mean? Basically it means the maintenance of strong and healthy animals with good genetic lines that can possibly be put back into the wild or at least saved from extinction by managed breeding in wildlife institutions.
Volumes have been written regarding the breeding of various species from the California Condor, the Florida Panther to the Grevey’s Zebra and many others. However, there is a flip side to breeding and that is contraception. Perhaps the idea of contraception in threatened or endangered captive animal species sounds counterproductive to the goal of conservation and preservation. It is not. Animal contraception is as important a piece of the reproductive management puzzle as the various AZA Breeding Programs.
Why is there a need for contraception?
Space is always a factor in captive animal institutions. As new animals are born, adequate space must be found to house them. If the institution does not have room another facility needs to be found. Can the animal be put back into the wild? Perhaps they can, but only under very strict introduction conditions. An animal that is not raised from the day of birth with reintroduction as a goal will seldom survive in the wild. In order to accomplish reintroduction, a complete and expensive infrastructure is required. To date, few species have been successfully put back into the wild.
Genetic Integrity in captive animals is a top priority in all captive management institutions. The Species Survival Plan (SSP) and other similar programs dictate which animals should breed together. But what do we do about all the other animals that are not on the breeding list? An institution must be sure these animals cannot breed whenever they wish and with any mate they choose. If random breeding takes place, animals would eventually breed with close genetic relatives. The gene mix would be weak and inbreeding would be the outcome which rapidly leads to the decrease in the overall reproductive intregrity of the species.
In the wild an animal would move into another breeding group and new animals in turn migrate into theirs. This is a simple process that keeps the gene pool fresh and viable. It has worked from day one. On the other hand, in a captive situation, an animal’s normal breeding behavior could be modified. In a zoo setting there may not be enough room to move into a new group unless another AZA facility has room to take the young offspring. Even if space is available the transfer may not occur before the onset of puberty surprises the keepers.
Financial issues are a more practical side of animal management and these are always important issues to consider. The St Louis Zoo spends about $600,000 a year on food for its animal collection. Other AZA facilities throughout the country spend comparable amounts depending upon their size. Human resources are another issue to consider. The number of potential qualified and trained keepers, curators and other wildlife managers may be abundant; however, the money to pay them is not. It is expensive to provide the best food, the wonderful care and beautiful grounds that we find at the various AZA institutions throughout North America.
All of these factors lead to the concept of parenthood planning and why contraception is used at captive animal facilities throughout the world. However, many questions arise before contraception medication can be given.
What type of drug should be used? How is the drug to be administered? When should the drug be administered? What is the proper dosage for a particular animal? All of these considerations must be carefully addressed.
In 1989, almost twenty years ago, the AZA established a Contraception Advisory Group. The board consisted of specialists in reproduction, veterinary medicine and animal management. A great deal of research needed to be done and many questions required answers before the Group could begin doing its assigned task.
The reproductive cycle of humans and many other primate species was well known but limited research had been done on the more exotic species that may not show outward signs of estrus periods. Clinical information needed to be collected before sound advice concerning contraceptive methods could be given to wildlife managers. This type of research continues today in many breeding facilities throughout the world.
The AZA established The Wildlife Contraception Center (WCC) at the Saint Louis Zoo in the year 2000. The Center is funded by the Saint Louis Zoo along with some earned income and donations. AZA pays the Program Coordinator salary. Today the board consists of scientists, veterinarians, animal managers and biologists all of whom are experts in their field of animal study. The Director of the WCC is Cheryl Asa, PhD, Director of Research at the Saint Louis Zoo, Ingrid Porton, MS, Saint Louis Zoo is Assistant Director and the Program Coordinator is Sally Boutelle, a reproductive physiologist with a MS degree.
With the shared research and knowledge of these people and the feed back from the institutions they work with,
a data base has been created containing over 21,000 contraceptive records. It is the mission of the Wildlife Contraceptive Center to give zoos and wildlife institutions in the US and throughout the world the following services:
- Ensure safe and effective contraception information
- Monitor reversibility data
- Serve as a Information Help-Line
- Educate zoos and wildlife institutions about new products
- Help determine appropriate contraception for each animal species
- Serve as a commercial liaison to companies producing contraceptives
- Generate FDA reports, dose calculations etc.
When a captive animal institution asks for information or assistance from the WCC certain steps need to be
taken before any advice on contraception can be given.
First, information is gathered on the class, family and species of the animal. Then questions are asked concerning the institutions goal for the animal. Is this a long term contraception plan of a year, perhaps more, or is it a short term solution to a breeding problem. Is the animal scheduled to breed in the future? The time line is important information which helps with the recommendation of drugs and method of delivery.
Specific needs of the individual are also taken into account. Is the need for contraception based on male aggression problems? Male aggression in animals such as dolphins or gorillas that may be living in a bachelor group can be curbed with the use of GnRH agonist products that reduce testosterone. Is the animal young or old, healthy or not? Can it be put under anesthesia for an implant? What about “THE PILL”? Chimpanzees usually take it without complaint as long as it is hidden in a spoon full of raspberry yogurt or the like. Orangutans are a different agenda. They usually take great delight in fooling their keepers. Usually by eating the treat, hiding the pill and spitting it out once the keepers turn their back. One must get up very early to fool an Orangutan and even then you are at a disadvantage.
The wildlife manager also needs to make sure the animal to receive contraception is not pregnant. Some contraceptive hormones may impede offspring birth in select species; therefore managers are always cautioned to check. Of course, there are always other special circumstances, such as the “Movie Star” baboon, Nyala, who is kept on contraceptives so is she always ready for her close-up.
Once all the information on the individual animal is processed the WCC will compile a list of contraception drug options with methods for delivery. The final decision is always made by the wildlife facility requesting the information. They are the only people who know the institution’s capability and how to keep the animal’s best interest a top priority.
As with humans, all the planning doesn’t mean there isn’t an “OOPS” now and then. One morning, about eighteen months ago, we learned the Saint Louis Zoo had a new baby camel. Everyone was excited and cameras came out of backpacks to record the new addition. After much excited chatter we realized no one seemed to know the zoo was expecting a baby……. and neither did the keepers! Our surprise child “Heidi” is now sharing the yard with her parents Celeste and Elvis. Heidi was so cute when she was born. She had humps but no fat in them so the humps just flopped over on her back. She is getting to be a big girl now, humps and all.
There are many different types of contraceptive medications. The drugs recommended most often by the WCC contains progestin which is a synthetic form of the pregnancy hormone progesterone. The different progestin products vary.
Melengesterol Acetate ( MGA ) Implant MGA Implants have the advantage of a long term balanced release for up to 2 years or more. They are used often because there is a great deal of data available on the implant. One disadvantage to the product is that the animal needs to be anesthetized for the procedure. Implants work well with ungulates and they are effective for primates. However implants may not be the best option for all primates. Some will pick at the area while grooming another member of the troop and this can cause infection. Another disadvantage to the MGA
implants, as well as other steroid-based methods, is that it can cause serious side effects such as mammary and
uterine cancer in carnivores.
Contraceptive feed is restricted by the FDA for use only in ungulates. The drawback is making sure the animal gets enough of the food. If an animal is off its feed for even one day, pregnancy could be the outcome.
In order to combat the eating problem with feed, a dose of MGA Liquid can be put on or into some food treat the animal likes. This is great for a hippopotamus, just pop an apple in its mouth. Unfortunately, the trick does not always work with giraffes. They are very picky eaters and will sometimes spit it right back out.
Depo Provera Injection
Progestin injections can be effective for 2-3 months and are often administered by dart. Injections work very well for hoof stock and darting is an easy process assuming the veterinarian with the dart gun is proficient at the job. The drawback is the dart may fall out too quickly and thus fail to deliver a full dose. Small primates are good candidates for injections as well. Many are trained to present an arm for the purpose, others can easily be darted.
Implanon implants have recently been approved by the FDA for use in the United States. Although the implant has been used in Europe, Indonesia and Australia for some time the popularity of the devise in the US is yet to be measured.
This implant is no longer used in the US because it can be a problem to remove. The implant consists of multiple silastic bars which can migrate from the original implant site. Norplant is still approved for use in Europe.
Birth Control Pills
There are many different brands of combination birth control pills that can be prescribed for humans and various wildlife species. The pill is also a safe and effective method of contraception for the great apes assuming you can outsmart the orangutans.
Progestin-only pills are seldom prescribed unless the female is nursing.
GnRH Agonist Products
These products work with the hypothalamus, one of the control centers in your brain. The hypothalamus controls temperature, sleep patterns, appetite and the hormonal secretions of the pituitary gland as well as the hormones involved in reproduction. The GnRH agonist products curtail the hormone messages sent to the reproductive organs.
Lupron® Depot Injections are made for humans and thus remain quite expensive. Another product is a Suprelorin® Implant, specifically made for animals so it is much less costly. These products have increased in use during the past four years, especially for carnivores, since they are a safe alternative to the steroid hormones. Suprelorin® also works well for male aggression.
Porcine Zona Pellucida Vaccine
This vaccine is most often used on horses and other hoofed animals. The vaccine does not stop the female from cycling. Instead, it attacks the female egg to prevent the sperm from penetration. The vaccine is safe for pregnant and lactating females, an added benefit when herds are large and individual animals are hard to keep track of. Vaccinations of this type are not recommended for most carnivores because just one use can result in infertility.
OvoControl is a feed used for birds, usually by golf courses, parks and other areas that have a pest problem. The effectiveness of the feed is once again dependent upon the intake by the bird. One component of the drug stops the production of the amnion membrane another inhibits the avian egg from hatching. Little research has been done to date on reptile contraception. Basically there didn’t seem to be a need because reptiles are not social animals and can easily be kept apart. However, the philosophy is changing and there is an increasing need to prevent some female birds and reptiles from having cycles and laying eggs. So, the research continues.
The field of captive wildlife contraception is relatively new, however the science of contraception in these animals is extremely complex. At this point in time, all contraceptives carry some risk for the animal. This is true of all animals including humans. The risk factors of contraception use always need to be compared to the risks of pregnancy and parturition. It is the goal of the Wildlife Contraception Center here at the Saint Louis Zoo as well as researchers and wildlife managers throughout the world to bring that risk as close to zero as possible.
As improvements in veterinary care, nutrition and husbandry of captive wildlife increase, we will witness higher birth rates and longer life spans in our animals. There is no doubt that contraception will continue to grow into a larger piece of the captive animal management puzzle.
I wish to thank Dr. Cheryl Asa and Sally Boutelle for their thoughtful review and critique of this paper.
Asa, Cheryl S., Ingrid J. Porton
Wildlife Contraception, Issues, Methods & Applications, Johns Hopkins University Press
Mother Nature, Ballantine Books New York
Wild Mammals in Captivity, Principles and Techniques
Saint Louis Zoo Web Site