How Fast Should We Grow Giant Tortoises? How Fast Should We Grow Long-Lived Tortoises?

Olddog

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How Fast Should We Grow Giant Tortoises? How Fast Should We Grow Long-Lived Tortoises?


In captivity, we are capable of feeding a young tortoise ample quantity of nutritious foods with high fiber content on a daily basis in order to maximize growth. Is this what is best for the tortoise?? Many stewards of giant or long-lived tortoise hatchlings seem to want their tortoises to grow large as possible as quickly as possible, feeding quantities of tortoise pellets, produce, and other nutritious and easily digested foods daily to achieve rapid growth. Feeding to achieve this goal will likely result in premature mortality and morbidity. Care in the first ten years is critical. Consider a male Galapagos may hatch at a weight of 70 grams and potentially grow to 500 plus lbs. (227 kg), a multiple in excess of 3200. Females more likely will achieve a potential growth factor of nearer 1500. Proper husbandry in the first 10% of life is critical for these tortoises to achieve their genetic potential. How best to achieve this remains controversial.


The Galapagos tortoises have been the subject of more documented research than the Aldabra tortoises but there are many similarities. The reader will have to determine if any of the following is applicable to tortoise species with which they are working. The author does not claim expertise but rather is attempting to share knowledge and insight acquired over time. Clearly some experienced breeders on the Tortoise Forum incorporate husbandry practices similar to those found appropriate with these gentle giants. The following remarks will be confined to the Galapagos tortoises (Chelonoidis nigra) which has been the subject of study, observations, and publications over many years. Nomenclature continually changes regarding species and subspecies. Certain subspecies are extinct, with the others being listed as Critically Endangered, Endangered, or Vulnerable. Nomenclature will be left to others and for purposes of this discussion, all subspecies are considered together. They have been extensively studied in the wild in their various habitats as well as in captivity. Studbook data confirms in many cases, we (author included) have not done a good job with husbandry of young animals in the past. Adults are much more forgiving. Fortunately, we know much more than we did 20-30 years ago and hopefully we will continue to learn.


Several thousand of the various subspecies of Galapagos tortoises have been hatched and raised in captivity on the Galapagos Islands. There are research stations on both Santa Cruz and Isabella islands. Tortoises have been hatched and “head started”, initially for 5 years or more and later as much as 8 years before release to their native habitat. Hatchlings are raised under conditions to promote growth and conditioning similar to what they might achieve in the wild. When they are large enough to likely escape predation and survive, they are repatriated to the wild. There is still significant mortality following repatriation, largely related to adverse environmental factors. Sun, exercise (including climbing for food), and limited groceries are part of the islands’ husbandry programs in these formative years.

BreedingCTrhatch_b.jpg

There are several videos of the Galapagos rearing facilities available on YouTube.


Zoo Zurich, Zurich, Switzerland, kept their Aldabra and Galapagos tortoises together and they received the same diet. They changed their adult giant tortoise diet following a 1983 death of a giant Aldabra tortoise with renal failure and severe visceral gout. The first two Galapagos hatchlings born there in 1992 died after 14 and 15 months, one with chronic interstitial pneumonia, the other with “slight interstitial nephritis and thymitis. In addition, both animals developed signs of Metabolic Bone Disease (MBD). They also reported on four Aldabra tortoises who arrived in 1964 as 6 month old imports. They required euthanasia at between 10 and 12 years due to MBD described as rickets combined with osteodystrophy. The diet prior to 1983 consisted of 15% (by volume) lettuce, 20 % bananas, 30% tomatoes, 30% apples and pears, 5% minced meat, green corn in summer, and grass 3x/week in summer. Ca-grit was used as a supplement. The new diet of 1984 consisted of Kale, red cabbage 15%, carrots 45%, various vegetables 30%, carob 5%, shredded horn, shrimpmeal 3%, Ca-grit 1.5%, Carnicon 0.5% as well as grass , fresh leaves 3x /week in summer and chopped hay 3x / week in winter. (https://dokumen.tips/documents/mana...ne-elephantopus-and-geochelone-gigantean.html)


In 2004, the Zoo Zurich published a report on the growth rates of their captive raised tortoises as compared to the growth rates of tortoises raised at the Charles Darwin Research Station (CDRS) in the Galapagos Islands, Ecuador. They found considerable discrepancies in growth rates between the ages of 1-4 years. (https://doi.org/10.1002/zoo.10130)


Comparison of the weights of Galapagos giant tortoises from Zoo Zurich and CDRS

Weights.png
https://www.researchgate.net/figure/Comparison-of-the-weights-of-Galapagos-giant-tortoises-from-Zoo-Zurich-and-the-CDRS-Bars_fig1_230045908


Comparison of the carapace lengths of Galapagos giant tortoises from Zoo Zurich and the CDRS
Carapace lengths.png

https://www.semanticscholar.org/paper/Comparative-Study-on-the-Growth-of-Juvenile-Giant-(-Furrer-Hatt/ee9109b00009b95ae31c01c186bbbb7a90e25a75/figure/1

At 4 years of age, the Zurich Zoo raised tortoises weighed about 10 times as much as the CDRS animals and were twice as long. Subsequently the zoo diet was modified to produce a more natural growth rate.

There are multiple photos of deformed tortoises fed a diet of primarily of dog food or other inappropriate diets in the veterinary literature.


Twenty plus years ago the author raised a group of young Galapagos tortoises in South Florida in a large wire enclosed outdoor aviary in which parrots were housed overhead in suspended cages. This arrangement protected the young tortoises from predators. It was a particularly rainy year (warm and humid). Part of the aviary was covered, and part exposed to sun and rains. The parrots’ feed areas were under cover such that food remained dry. The tortoises had a heated “night box” for inclement weather. In addition to daily produce and occasional seed, the parrots were fed a diet primarily of Kaytee parrot pellets. Some of what they spilled was eaten by the tortoises. Veterinary and experienced reptile breeder consultation was obtained. At the time this was an ideal environment and minor adjustments were made when suggested. There was plenty of room for exercise. Grass and occasional germinated spilled seed were plentiful, far more than this small group of young tortoises would eat. The extra protein and nutrition from the spilled parrot pellets and other foods resulted in rapid growth. Unfortunately, shell deformity and MBD also resulted in several. Subsequently some cannot walk normally and are stunted. Some of these animals will never grow to their potential or be able to breed.

Examples of deformities
IMG_2369.jpg
IMG_2368.jpg IMG_2351.jpg
IMG_2397.jpg
IMG_2402.jpg

It is felt this abnormal growth was iatrogenic, a direct result of malnutrition resulting from an excess of easily digested groceries (protein) likely without adequate crude fiber. One of the parent tortoises of this group was known to produce occasional deformed offspring and undoubtedly there may be a genetic predisposition. In addition to desiccating basking lamps or sun in conditions of low humidity, other factors such as vitamin toxicity or deficiency, minerals, lack of sun, fast growth rates, lack of exercise, genetics, etc., have been suggested as contributing factors to pyramiding and shell deformity. Likely there are many factors which can influence the growth and development of the scutes and bone in these formative years.


Jarchow (http://www.deserttortoise.org/ocr_DTCdocs/1984Proceedings-OCR.pdf page 83-94) compared the crude fiber content of grocery store produce typically fed captive tortoises with that of typical wild foods of the desert tortoise. The grocery store produce being fed had a significantly lower crude fiber percentage than plants consumed in the native diet. Some of the captive fed foods had higher fat content and lower calcium-phosphorus ratios or lower calcium levels than levels expected from the native diet. He felt this diet related to the incidence of documented MBD in the captive raised tortoises.

The potential morbidity of rapid growth in giant tortoises has been recognized for at least the past ten years. Hiatt cautioned“The fast growth observed in giant tortoises must controlled by limiting the amount of food and reducing digestibility. Giant tortoises are well adapted to a high fiber, herbivore diet. Special attention must be given to the mineral supplementation and photoenvironment.” (http://www.zora.uzh.ch/id/eprint/10240/2/ZAWAM_6V.pdf, 2008).

Previously Hatt etal measured digestibility in different fiber fractions using a high crude fiber diet (20.5% dry matter). Their studies showed an increase in crude fiber reduced digestibility in juvenile Galapagos tortoises. They suggested but did not study diets of 30-40% crude fiber for Galapagos tortoises. They showed juvenile Galapagos tortoises demonstrated a digestion of crude fiber of similar efficiency as domestic horses.(https://www.researchgate.net/profil...tive-Galapagos-tortoises-Geochelone-nigra.pdf)

At the 2014 ARAV meeting, Adams C.H.,etal. (Failing the Galapagos Tortoise(Chelonoidis nigra): Death and Body Changes Resulting from Poor Husbandry)(https://propertibazar.com/queue/fai...f-reptilian-and_5b196434d64ab24602eec1da.html) reported many of the hundreds of captive F1 offspring produced over the last 30 years have failed to survive. They reported health issues related to husbandry. These animals have often exhibited rapid growth, ambulatory issues, edema, and morphological abnormalities. There has been a high incidence of associated fatal hepatological and cardiac disease. For purposes of this discussion, this will be called “Rapid Growth Syndrome” (RGS) although clearly more is involved than nutrition alone.


Adams, etal. suggested use of husbandry techniques to” better mimic wild conditions and accommodate the massive growth potential, long life, and impressive mobility of giant tortoises. This includes the elimination of highly digestible food stuffs from the captive diet, reducing the volume of food offered, providing a hard, rough substrate, and mandating routine exercise.”

Below is one of two genetically valuable animals sent to our facility with advanced “RGS” disease. They were quite edematous on arrival and were virtually unable to walk. The thought was that they were going to die, there was nothing to lose, and perhaps they might improve on the ranch setting. They were initially kept in a quarantine area. One tortoise never made meaningful recovery, succumbing to her hepatic and heart failure. After a prolonged quarantine period in which some ability to ambulate was restored, the second tortoise, a Chelonoidis nigra becki(whose genetically valuable mother has been dead for many years) was treated with “tough love”. As a beckishe is genetically smaller than other subspecies of Galapagos tortoises. One cannot judge her age by the scute “rings”. She has reached maturity to the point that her shell is developingbeckiflaring in the anterior and posterior portions of her carapace. Due to her goiter she has had some empiric iodine supplementation but otherwise her diet has consisted almost entirely of grasses (primarily Byhalia). She has spent an inordinate amount of time in the water compared to the other tortoises. She spent most of her days in the water last summer and fall. When it warmed enough in spring, she wallowed out mud soaks. Currently (August) she spends her nights and much of her day in her mud wallow or pond (as do many of the Galapagos tortoises). She can now raise her posterior and walk rapidly enough to easily outrun a larger male. She does not fully rise on her hind legs and still has some lateral sweep. The edematous throat is now a sack which sometimes contains fluid. What were massive areas of edema over her front and back legs are now flaps of skin which sometimes contains fluid but certainly is quite different from the tense interstitial edema she had for years. Videos are from April and August of this year. Notice she is unable to get her back legs completely under her plastron and raise herself fully on the hind legs, instead using a lateral sweeping motion of her back legs. This has allowed an elongation of her back claws; however, she can rapidly ambulate wherever she wants. How much the cardiomyopathy will reverse and how she will do in the long term is unknown. She has made marked symptomatic improvement with her prolonged soakings, grass, exercise, and sun. The amount of fluid in her residual skin flaps seems to vary from week to week. This improvement suggests this “RGS” manifested by rapid growth, edema, morphological changes, impaired ambulation and inability to fully stand, hepatic, and cardiac disease may be partially reversible with husbandry changes, confirming Adams, etal., recommendation regarding husbandry.

Videos

There has not been agreement on diets for giant tortoises in various institutions and breeder facilities. Some tortoises have been raised on easily digested bagged feeds, produce and greens with limited space, exercise, and crude fiber. Some facilities give extra protein periodically. Other facilities do an excellent job in providing for these tortoises with grasses, hay, supplements, exercise, and UV light.


AZA Galapagos Studbook (2012) Appendix on diet suggestions include:

Grass, hay & leafy browse = 85% of diet
– Offer daily


Cactus & grocery store greens = 13% of diet
– Offer in moderation (no more than what can be eaten in ten minutes) 2 X week


Tortoise chow & others = 2% of diet
– Feed like bonbons
– No more than once weekly


Suggested food items
• Grass
• Hay: Bermuda, Timothy, Alfalfa
• Edible leaves & flowers
• Hibiscus
• Turk’s cap
• Local species (?)
Opuntia cactus pads
• Green leafy grocery store veggies


In moderation only
• Tortoise Chow: Soaked, Volume as big as tortoise’s head X once weekly
• Carrot or sweet potato: Most benign, given in moderation, but only as a tool to condition or stimulate exercise
• Apple and other fruits: Should be considered as treats. Only with exercise, no more than once weekly

At the Isabella research station the 2-4 yo tortoises being “head started” are fed three days per week with a “traditional diet” based on Xanthosoma sagittifoliun (otoy,yautia or malanga) elephant ear.( http://www.annexpublishers.co/artic...-in-Captivity-at-Isabela-Island-Galapagos.pdf)
(This species appears on the Florida Noxious Weed List and is legally prohibited in Florida.) Various other diets have also been trialed including ones listed in the above referenced paper.


It is difficult to test for a vitamin or mineral deficiency or toxicity from a single or limited blood samples. It may be reasonable to periodically give a multivitamin with minerals or similar supplement. Toxicity can occur from over supplementation. There is little good data. Nutritional secondary hyperparathyroidism is reported to be a very common cause of metabolic bone disease in reptiles due to either inadequate calcium intake or low calcium to phosphorus ratios, and lack of adequate ultraviolet light. This results in lack of appropriate levels of vitamin D3. It may be prudent to provide calcium supplementation. If Opuntia is not regularly fed or if there is any question of adequate calcium intake with a high calcium to phosphorus ratio, supplementation with calcium carbonate (food grade ground limestone) may be considered. This may also be considered when foods high in oxalates are fed. Sun or an adequate source of ultraviolet light is required. There are many ways to appropriately supplement calcium, vitamins, and trace minerals.

Exercise (on a non-slick surface) is mandatory for young tortoises. They show be observed for signs of problems associated with “RGS”. If too rapid growth is evidenced by failure to stand fully on the hind legs or ambulate appropriately, husbandry changes should be made as soon as possible to try to prevent disease progression.

The author has not witnessed the “RGS” in primarily grass/pasture raised Galapagos tortoises. Unfortunately, despite fencing, pasture raised animals are subject to predators, particularly raccoons.

In summary, slow and steady growth of giant tortoises is preferable to rapid growth for health reasons, some of which are illustrated above. Bagged tortoise chow and grocery store produce are not the dietary answer during these formative years. Adults can usually safely graze grasses free choice if no sudden dietary changes are made. It is questionable if 1-5-year-old tortoises, even those raised on high crude fiber diets or grass, should be fed to satiety on a daily basis. There is much to suggest that slow growth on a high crude fiber diet over the first 10% of these tortoises’ lives is advantageous to tortoises’ long-term health.
 

wellington

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I'm only giving my opinion on the first couple things you said. First, I don't think most of us feed any of our torts the amounts we do to grow them fast and big. It's what we think they would do in the wild. Graze on and off all day. Hopefully most will feed as natural a diet as possible when possible. Making store greens a small part of the diet or only a winter diet.
Second, I wouldn't count on those zoo's etc to know what they are doing. Many have too many torts in a too small of a space with little to no grazing grounds and therefore fed 100% prepared foods.
Also the lack of knowledge from when those in the pics were hatched and raised were almost nonexistent.
Oh and I highly doubt a tort in the wild will purposely not eat every day. They may get less on some days and more on others. However, not likely they go a day without eating. In our care we do feed them every day and the same amounts. If anything we should maybe make some days not as plentiful as others, but I don't think days should be skipped.
 

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Excellent article. I greatly appreciate and would like to explore the discussion. Do you believe this to be more of an issue with the two "giant" tortoises as opposed to other tortoises?

Over the years, it seemed almost the norm, to very commonly see tortoises of many species in conditions similar to what you picture with the tortoises in your examples. In the last 20 years in particular, there seems to be more and more examples of what certainly appear to be healthy, natural looking tortoises now being raised by the well informed keeper. It seems the improvements in husbandry, e.g. the diet, UVB exposure, better lighting, better understanding of environmental temp and humidity provided, and ample room - have led to an almost non-existent examples of cases like this today. This certainly seems to be independent totally of rapid growth and food quantity availability.

In relation to size "ample room" would be much easier to provide with most species of tortoises as opposed to the giants. I personally have dealt extensively with sulcatas (the 3rd largest and called a "giant" in some regards) for over 28 years now. With sulcatas, I feel we have a smaller "giant" and indeed was perhaps the most common species in seeing examples like you show above. It also, as of the past 25 years now, has become an extremely common tortoise for the backyard tortoise keeper, so countless examples are now available as opposed to Aldabras or Galops. With so many available, the quest for best husbandry practices perhaps was accelerated greatly. This did not, for the most part, happen at zoos. The serious hobbyist almost possessed with a quest for answers, seemed to be the best sources. Just as you are doing with Galopagos, and Aldabraman with Aldabras. But there were countless examples instead of the few for the true giants.

I can not speak to the two giants as I have no experience there. I feel the true scarcity of examples and the even rarer example of someone with ample room for these true giants put some of the answers there in its infancy compared to more common species. Perhaps some of the RGS issues you outline will lead to learnings helpful to other species as well. I will speak to this in reference to sulcatas.

All of the issues you mention above were constantly tried and scrutinized. All of the issues had great impact in healthy tortoises, except - rapid growth. I have tried everything I could ever uncover to see best results. I have raised over 100 to sexable size. I have F1 examples that have all the appearanced os heathy, thriving adults now at 20 - 28 years old. I have never had a sulcata with MBD, or one with any mobility issues. I was, however, driven crazy with pyramiding. In efforts to solve that issue I tried everything. Most had to do with the common thought culprit of the time - diet. I tired every mixture I could think in side by side groups. Some with store bought, others with only free range graze and were never fed anything they could not find in their yards. I even raised a group on commercial pellets as 90% of their diet the first 3 years. I slow grew some that averaged 8" by 4 years old, and let others eat all they wanted with provided piles of food - that grew to 8" in 16-18 months. None ever developed MBC or mobility issues. None appeared to be unhealthy in every aspect I could judge. But they did still pyramid. Only in the past 7 years or so since I came across @Tom 's experiment and Daisy, did I finally put humidity into the equation and now grow very smooth and "natural" looking sulcatas. I feel that is an important part of the equation. In fact, with your and @ALDABRAMAN 's examples, I enjoy seeing countless pictures of your tortoises wallowing in pools and mud holes. Yet I have never seen a giant kept in a zoo where that was available up until a few examples very recently. I personally feel the tortoises' need for water has been dramatically missing in the equation. Especially in the early growing years. While the shell is actively growing and the organs are growing, hydration is a key ingredient.

So I follow with great interest your findings and love your willingness to share and formulate conclusions on the open forum. As stated, I cannot and will not speak to the two giants, but for the sulcatas (and stars) I feel speed of growth is not a factor.
 

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Who is the author of this article? @Olddog is this your article or a reprint of someone else's work?

Here is what I get from the article:
  1. Feeding a giant tortoise parrot food, shrimp meal, dog or cat food, fruit and grocery store greens causes problems.
  2. Housing a tortoise in too small of an enclosure causes problems.
Forgive my flippancy, but this is exactly what I and most other people have been harping on here at TFO for years. This is good info, but this is where I was more than 20 years ago.

Likewise, due to annual rainfall and typical humidity, I find the residents of South FL underestimate the importance of hydration and humidity in this equation.

Slow, or fast, growth has never been my goal. Healthy growth is what I am after. Faster than average growth is perfectly fine and does no harm as long as the animal is being fed the right foods, is being kept well hydrated, is getting UV and and is getting plenty of exercise in a large well-designed enclosure. @Markw84 and I, as well as many other people, tried the slow growth and food deprivation method. It doesn't solve the pyramiding issue and it can cause some other serious issues. Starving the tortoises to make up for other husbandry issues is not the way to go in my experience.

As Mark also mentioned, hydration is key. In some of the fatalities listed in the article kidney problems were listed. It is worth mentioning my side-by-side experiments here. A well hydrated tortoise kept in idyllic monsoon style conditions will grow 2 to 3 times faster than a clutch mate that is fed the same foods in the same quantities. Further, these faster growers will grow up to be healthy, structurally sound, reproducing animals further down the road, and have significantly less pyramiding. This is a key point that needs to be explained in this sort of discussion. Why are they growing faster on the same amount of food? Its because they are healthier and being cared for correctly. Forced slow growth due to food deprivation fails to address the other significant husbandry problems.

In summary, I've seen the problems with giants discussed here. Saw it with Galops, Aldabras and with many sulcatas. The problem is not "fast" growth. The problem is incorrect diet, small enclosures, lack of UV, and inadequate hydration. Put a Galop in a large enclosure, preferably with some hills, with good UV, soak it daily, and you can let it eat as much mulberry leaves, opuntia pads, grass, grass hay, weeds, hibiscus leaves, grape leaves, and other foods of this nature, as it wants. Growth and structure will be healthy, regardless of growth rate. Let the same tortoise eat fruit, lettuce, carrots, tomatoes, parrot food and parrot feces, shrimp meal or other similarly inappropriate foods, and growth will be unhealthy, regardless of rate. Likewise, confine a giant tortoise to a back yard sized enclosure, as many zoos do, and orthopedic problems abound. This is why I keep telling people they can't keep their russian tortoise in a 40 gallon tank, and suggest 4x8' as a minimum for a single little russian tortoise.

I appreciate the article and insight, but it seems the author, whoever it is, has a ways to go to catch up.
 

galapagosgirl1

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How Fast Should We Grow Giant Tortoises? How Fast Should We Grow Long-Lived Tortoises?


In captivity, we are capable of feeding a young tortoise ample quantity of nutritious foods with high fiber content on a daily basis in order to maximize growth. Is this what is best for the tortoise?? Many stewards of giant or long-lived tortoise hatchlings seem to want their tortoises to grow large as possible as quickly as possible, feeding quantities of tortoise pellets, produce, and other nutritious and easily digested foods daily to achieve rapid growth. Feeding to achieve this goal will likely result in premature mortality and morbidity. Care in the first ten years is critical. Consider a male Galapagos may hatch at a weight of 70 grams and potentially grow to 500 plus lbs. (227 kg), a multiple in excess of 3200. Females more likely will achieve a potential growth factor of nearer 1500. Proper husbandry in the first 10% of life is critical for these tortoises to achieve their genetic potential. How best to achieve this remains controversial.


The Galapagos tortoises have been the subject of more documented research than the Aldabra tortoises but there are many similarities. The reader will have to determine if any of the following is applicable to tortoise species with which they are working. The author does not claim expertise but rather is attempting to share knowledge and insight acquired over time. Clearly some experienced breeders on the Tortoise Forum incorporate husbandry practices similar to those found appropriate with these gentle giants. The following remarks will be confined to the Galapagos tortoises (Chelonoidis nigra) which has been the subject of study, observations, and publications over many years. Nomenclature continually changes regarding species and subspecies. Certain subspecies are extinct, with the others being listed as Critically Endangered, Endangered, or Vulnerable. Nomenclature will be left to others and for purposes of this discussion, all subspecies are considered together. They have been extensively studied in the wild in their various habitats as well as in captivity. Studbook data confirms in many cases, we (author included) have not done a good job with husbandry of young animals in the past. Adults are much more forgiving. Fortunately, we know much more than we did 20-30 years ago and hopefully we will continue to learn.


Several thousand of the various subspecies of Galapagos tortoises have been hatched and raised in captivity on the Galapagos Islands. There are research stations on both Santa Cruz and Isabella islands. Tortoises have been hatched and “head started”, initially for 5 years or more and later as much as 8 years before release to their native habitat. Hatchlings are raised under conditions to promote growth and conditioning similar to what they might achieve in the wild. When they are large enough to likely escape predation and survive, they are repatriated to the wild. There is still significant mortality following repatriation, largely related to adverse environmental factors. Sun, exercise (including climbing for food), and limited groceries are part of the islands’ husbandry programs in these formative years.

View attachment 248657

There are several videos of the Galapagos rearing facilities available on YouTube.


Zoo Zurich, Zurich, Switzerland, kept their Aldabra and Galapagos tortoises together and they received the same diet. They changed their adult giant tortoise diet following a 1983 death of a giant Aldabra tortoise with renal failure and severe visceral gout. The first two Galapagos hatchlings born there in 1992 died after 14 and 15 months, one with chronic interstitial pneumonia, the other with “slight interstitial nephritis and thymitis. In addition, both animals developed signs of Metabolic Bone Disease (MBD). They also reported on four Aldabra tortoises who arrived in 1964 as 6 month old imports. They required euthanasia at between 10 and 12 years due to MBD described as rickets combined with osteodystrophy. The diet prior to 1983 consisted of 15% (by volume) lettuce, 20 % bananas, 30% tomatoes, 30% apples and pears, 5% minced meat, green corn in summer, and grass 3x/week in summer. Ca-grit was used as a supplement. The new diet of 1984 consisted of Kale, red cabbage 15%, carrots 45%, various vegetables 30%, carob 5%, shredded horn, shrimpmeal 3%, Ca-grit 1.5%, Carnicon 0.5% as well as grass , fresh leaves 3x /week in summer and chopped hay 3x / week in winter. (https://dokumen.tips/documents/mana...ne-elephantopus-and-geochelone-gigantean.html)


In 2004, the Zoo Zurich published a report on the growth rates of their captive raised tortoises as compared to the growth rates of tortoises raised at the Charles Darwin Research Station (CDRS) in the Galapagos Islands, Ecuador. They found considerable discrepancies in growth rates between the ages of 1-4 years. (https://doi.org/10.1002/zoo.10130)


Comparison of the weights of Galapagos giant tortoises from Zoo Zurich and CDRS

View attachment 248658
https://www.researchgate.net/figure/Comparison-of-the-weights-of-Galapagos-giant-tortoises-from-Zoo-Zurich-and-the-CDRS-Bars_fig1_230045908


Comparison of the carapace lengths of Galapagos giant tortoises from Zoo Zurich and the CDRS
View attachment 248659

https://www.semanticscholar.org/paper/Comparative-Study-on-the-Growth-of-Juvenile-Giant-(-Furrer-Hatt/ee9109b00009b95ae31c01c186bbbb7a90e25a75/figure/1

At 4 years of age, the Zurich Zoo raised tortoises weighed about 10 times as much as the CDRS animals and were twice as long. Subsequently the zoo diet was modified to produce a more natural growth rate.

There are multiple photos of deformed tortoises fed a diet of primarily of dog food or other inappropriate diets in the veterinary literature.


Twenty plus years ago the author raised a group of young Galapagos tortoises in South Florida in a large wire enclosed outdoor aviary in which parrots were housed overhead in suspended cages. This arrangement protected the young tortoises from predators. It was a particularly rainy year (warm and humid). Part of the aviary was covered, and part exposed to sun and rains. The parrots’ feed areas were under cover such that food remained dry. The tortoises had a heated “night box” for inclement weather. In addition to daily produce and occasional seed, the parrots were fed a diet primarily of Kaytee parrot pellets. Some of what they spilled was eaten by the tortoises. Veterinary and experienced reptile breeder consultation was obtained. At the time this was an ideal environment and minor adjustments were made when suggested. There was plenty of room for exercise. Grass and occasional germinated spilled seed were plentiful, far more than this small group of young tortoises would eat. The extra protein and nutrition from the spilled parrot pellets and other foods resulted in rapid growth. Unfortunately, shell deformity and MBD also resulted in several. Subsequently some cannot walk normally and are stunted. Some of these animals will never grow to their potential or be able to breed.

Examples of deformities
View attachment 248660
View attachment 248661 View attachment 248662
View attachment 248663
View attachment 248664

It is felt this abnormal growth was iatrogenic, a direct result of malnutrition resulting from an excess of easily digested groceries (protein) likely without adequate crude fiber. One of the parent tortoises of this group was known to produce occasional deformed offspring and undoubtedly there may be a genetic predisposition. In addition to desiccating basking lamps or sun in conditions of low humidity, other factors such as vitamin toxicity or deficiency, minerals, lack of sun, fast growth rates, lack of exercise, genetics, etc., have been suggested as contributing factors to pyramiding and shell deformity. Likely there are many factors which can influence the growth and development of the scutes and bone in these formative years.


Jarchow (http://www.deserttortoise.org/ocr_DTCdocs/1984Proceedings-OCR.pdf page 83-94) compared the crude fiber content of grocery store produce typically fed captive tortoises with that of typical wild foods of the desert tortoise. The grocery store produce being fed had a significantly lower crude fiber percentage than plants consumed in the native diet. Some of the captive fed foods had higher fat content and lower calcium-phosphorus ratios or lower calcium levels than levels expected from the native diet. He felt this diet related to the incidence of documented MBD in the captive raised tortoises.

The potential morbidity of rapid growth in giant tortoises has been recognized for at least the past ten years. Hiatt cautioned“The fast growth observed in giant tortoises must controlled by limiting the amount of food and reducing digestibility. Giant tortoises are well adapted to a high fiber, herbivore diet. Special attention must be given to the mineral supplementation and photoenvironment.” (http://www.zora.uzh.ch/id/eprint/10240/2/ZAWAM_6V.pdf, 2008).

Previously Hatt etal measured digestibility in different fiber fractions using a high crude fiber diet (20.5% dry matter). Their studies showed an increase in crude fiber reduced digestibility in juvenile Galapagos tortoises. They suggested but did not study diets of 30-40% crude fiber for Galapagos tortoises. They showed juvenile Galapagos tortoises demonstrated a digestion of crude fiber of similar efficiency as domestic horses.(https://www.researchgate.net/profil...tive-Galapagos-tortoises-Geochelone-nigra.pdf)

At the 2014 ARAV meeting, Adams C.H.,etal. (Failing the Galapagos Tortoise(Chelonoidis nigra): Death and Body Changes Resulting from Poor Husbandry)(https://propertibazar.com/queue/fai...f-reptilian-and_5b196434d64ab24602eec1da.html) reported many of the hundreds of captive F1 offspring produced over the last 30 years have failed to survive. They reported health issues related to husbandry. These animals have often exhibited rapid growth, ambulatory issues, edema, and morphological abnormalities. There has been a high incidence of associated fatal hepatological and cardiac disease. For purposes of this discussion, this will be called “Rapid Growth Syndrome” (RGS) although clearly more is involved than nutrition alone.


Adams, etal. suggested use of husbandry techniques to” better mimic wild conditions and accommodate the massive growth potential, long life, and impressive mobility of giant tortoises. This includes the elimination of highly digestible food stuffs from the captive diet, reducing the volume of food offered, providing a hard, rough substrate, and mandating routine exercise.”

Below is one of two genetically valuable animals sent to our facility with advanced “RGS” disease. They were quite edematous on arrival and were virtually unable to walk. The thought was that they were going to die, there was nothing to lose, and perhaps they might improve on the ranch setting. They were initially kept in a quarantine area. One tortoise never made meaningful recovery, succumbing to her hepatic and heart failure. After a prolonged quarantine period in which some ability to ambulate was restored, the second tortoise, a Chelonoidis nigra becki(whose genetically valuable mother has been dead for many years) was treated with “tough love”. As a beckishe is genetically smaller than other subspecies of Galapagos tortoises. One cannot judge her age by the scute “rings”. She has reached maturity to the point that her shell is developingbeckiflaring in the anterior and posterior portions of her carapace. Due to her goiter she has had some empiric iodine supplementation but otherwise her diet has consisted almost entirely of grasses (primarily Byhalia). She has spent an inordinate amount of time in the water compared to the other tortoises. She spent most of her days in the water last summer and fall. When it warmed enough in spring, she wallowed out mud soaks. Currently (August) she spends her nights and much of her day in her mud wallow or pond (as do many of the Galapagos tortoises). She can now raise her posterior and walk rapidly enough to easily outrun a larger male. She does not fully rise on her hind legs and still has some lateral sweep. The edematous throat is now a sack which sometimes contains fluid. What were massive areas of edema over her front and back legs are now flaps of skin which sometimes contains fluid but certainly is quite different from the tense interstitial edema she had for years. Videos are from April and August of this year. Notice she is unable to get her back legs completely under her plastron and raise herself fully on the hind legs, instead using a lateral sweeping motion of her back legs. This has allowed an elongation of her back claws; however, she can rapidly ambulate wherever she wants. How much the cardiomyopathy will reverse and how she will do in the long term is unknown. She has made marked symptomatic improvement with her prolonged soakings, grass, exercise, and sun. The amount of fluid in her residual skin flaps seems to vary from week to week. This improvement suggests this “RGS” manifested by rapid growth, edema, morphological changes, impaired ambulation and inability to fully stand, hepatic, and cardiac disease may be partially reversible with husbandry changes, confirming Adams, etal., recommendation regarding husbandry.

Videos

There has not been agreement on diets for giant tortoises in various institutions and breeder facilities. Some tortoises have been raised on easily digested bagged feeds, produce and greens with limited space, exercise, and crude fiber. Some facilities give extra protein periodically. Other facilities do an excellent job in providing for these tortoises with grasses, hay, supplements, exercise, and UV light.


AZA Galapagos Studbook (2012) Appendix on diet suggestions include:

Grass, hay & leafy browse = 85% of diet
– Offer daily


Cactus & grocery store greens = 13% of diet
– Offer in moderation (no more than what can be eaten in ten minutes) 2 X week


Tortoise chow & others = 2% of diet
– Feed like bonbons
– No more than once weekly


Suggested food items
• Grass
• Hay: Bermuda, Timothy, Alfalfa
• Edible leaves & flowers
• Hibiscus
• Turk’s cap
• Local species (?)
Opuntia cactus pads
• Green leafy grocery store veggies


In moderation only
• Tortoise Chow: Soaked, Volume as big as tortoise’s head X once weekly
• Carrot or sweet potato: Most benign, given in moderation, but only as a tool to condition or stimulate exercise
• Apple and other fruits: Should be considered as treats. Only with exercise, no more than once weekly

At the Isabella research station the 2-4 yo tortoises being “head started” are fed three days per week with a “traditional diet” based on Xanthosoma sagittifoliun (otoy,yautia or malanga) elephant ear.( http://www.annexpublishers.co/artic...-in-Captivity-at-Isabela-Island-Galapagos.pdf)
(This species appears on the Florida Noxious Weed List and is legally prohibited in Florida.) Various other diets have also been trialed including ones listed in the above referenced paper.


It is difficult to test for a vitamin or mineral deficiency or toxicity from a single or limited blood samples. It may be reasonable to periodically give a multivitamin with minerals or similar supplement. Toxicity can occur from over supplementation. There is little good data. Nutritional secondary hyperparathyroidism is reported to be a very common cause of metabolic bone disease in reptiles due to either inadequate calcium intake or low calcium to phosphorus ratios, and lack of adequate ultraviolet light. This results in lack of appropriate levels of vitamin D3. It may be prudent to provide calcium supplementation. If Opuntia is not regularly fed or if there is any question of adequate calcium intake with a high calcium to phosphorus ratio, supplementation with calcium carbonate (food grade ground limestone) may be considered. This may also be considered when foods high in oxalates are fed. Sun or an adequate source of ultraviolet light is required. There are many ways to appropriately supplement calcium, vitamins, and trace minerals.

Exercise (on a non-slick surface) is mandatory for young tortoises. They show be observed for signs of problems associated with “RGS”. If too rapid growth is evidenced by failure to stand fully on the hind legs or ambulate appropriately, husbandry changes should be made as soon as possible to try to prevent disease progression.

The author has not witnessed the “RGS” in primarily grass/pasture raised Galapagos tortoises. Unfortunately, despite fencing, pasture raised animals are subject to predators, particularly raccoons.

In summary, slow and steady growth of giant tortoises is preferable to rapid growth for health reasons, some of which are illustrated above. Bagged tortoise chow and grocery store produce are not the dietary answer during these formative years. Adults can usually safely graze grasses free choice if no sudden dietary changes are made. It is questionable if 1-5-year-old tortoises, even those raised on high crude fiber diets or grass, should be fed to satiety on a daily basis. There is much to suggest that slow growth on a high crude fiber diet over the first 10% of these tortoises’ lives is advantageous to tortoises’ long-term health.

I don't quite understand the negativity from Tom. That being said, I appreciated your post. This is an opportunity for those of us who are new, to learn from the sins of the past. I'm also grateful to the folks on this site that take care of their tortoises and try to do the right thing. For anyone who doesn't think there are people out there doing wrong, just attend a reptile show. I went to my first show in Daytona last week-end. Honestly, I left there sad and still think about it. I truly enjoy the Tortoise Forum but I don't enjoy the "flippancy." Once again, thank you from those of us who enjoy learning!
 

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having raised large dogs most all my life , your article rings familiar ……you won't get away with the nutritional and physical mistakes with big dogs as you will small dogs …..... something grows at that rate would have to be susceptible to orthopedic disorders , and as with dogs , it would be influenced by nutrition and exercise ............pyramiding I believe as markw says is not an orthopedic disorder it's the keratin deforming the growing bone , which is pliable ……… some of your distorted shells look like bone disorders ………….
 

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I don't quite understand the negativity from Tom. That being said, I appreciated your post. This is an opportunity for those of us who are new, to learn from the sins of the past. I'm also grateful to the folks on this site that take care of their tortoises and try to do the right thing. For anyone who doesn't think there are people out there doing wrong, just attend a reptile show. I went to my first show in Daytona last week-end. Honestly, I left there sad and still think about it. I truly enjoy the Tortoise Forum but I don't enjoy the "flippancy." Once again, thank you from those of us who enjoy learning!
What negativity? I simply acknowledged the pertinent points from the article and added more to the discussion. Food deprivation is not the solution to these problems. How is trying to give people a more complete explanation to solving these problems negative?
 

mark1

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I didn't get food deprivation out of that article , I got proper feeding , possibly I misread …….although in large dogs , under fed , free range pups do orthopedically turn out better than over fed , over supplemented , over weight , and under exercised pups …. strength and weight are major factors in orthopedic health , and actually overall health …….. wild tortoises as with most wild animals i'd think are more often underfed than overfed , and i'd bet the health problems highlighted in the article are far less common in the wild population ?
 

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Mark84

Thank you for your thoughtful response.

“Do you believe this to be more of an issue with the two "giant" tortoises as opposed to other tortoises?” [/QUOTE said:
I do not have enough experience with the physiology of other species to presume to say if material posted previously regarding “RGS” is applicable to other herbivories. Due to the size and weight of the giant tortoises, I suspect some problems become much more apparent than they might in smaller tortoises. I doubt there are large numbers of records regarding many species of captive raised tortoise’s morbidity and mortality so likely we, as groups of hobbyists, are unable to judge how well we are collectively doing with our husbandry as compared to wild. There are tortoise species cared for by dedicated stewards who are successfully raising and reproducing though several generations. Is this the norm or the exception?


[QUOTE="“…….But there were countless examples instead of the few for the true giants.”

I would respectfully disagree. There are studies of nesting behavior, incubation and growth rates for survival in these giants, at least in the case of the Galapagos tortoise on the Galapagos Islands. As of the end of last year, there has been in excess of 7000 Galapagos tortoises hatched, raised in captivity, and repatriated to their island of origin. I think this has now been done for 9 subspecies. This has been going on since 1965 with the first releases in 1970. There has been a series of difficult times and problems which have been overcome and incorporated into the repatriation programs. To quote Linda Cayot from 2008: “With improvements in methods resulting from the experiments in the 1980s, the tortoise program had even greater success in the 1990s. Routinely, 500–700 young tortoises (hatchlings to three-year-olds) were reared annually in the center; prior to 1991, the average had been 332 (range 53–462). Average mortality of young tortoises in the center was reduced to < 3 % per year, whereas in the 1980s it had been 18 % (range 4.2–31.8 %). The almost factory-like production of young tortoises allowed for the expansion of the program. Areas that received more attention during the 1990s included nutrition and general health, genetic analyses, and expansion of the program in southern Isabela. Much of the work was accomplished with the help of consultants and visiting scientists.”

On the islands the Galapagos National Park Directorate (GNPD) manages three tortoise centers. The Charles Darwin Research Station built in 1965 is now the Fausto Llerena Center on Santa Cruz. The Arnaldo Tupiza Tortoise Center was built on Isabela in 1995. A San Cristobal Tortoise Center was formed in 2004 but does not maintain a breeding colony. The first two facilitiesare raising tortoises for repatriation. For the first couple of years, tortoises are usually raised in outside pens which are covered with mesh at night for protection from rats and cats. Later they are transferred to “pre-repatriation” enclosures. Young tortoises receive grasses / leaves, sun, exercise, etc. On the islands it has pretty well determined what it takes to grow tortoises to increase their chances of survival in the various habitats. Repatriated tortoises clearly are not overweight. The overall survival varies with the habit, rainfall, etc. Pinzon survival rate of repatriated tortoises through 2008 was reported at 68-77%. Espanola with its harsher environment is lower, overall at least 55%. With changes associated with drought, etc., some years first year survival has been as low as 29%.

Zoological institutions have records on hundreds of Galapagos with mortality data.

In short, I respectfully suggest there has been no shortage of studies/data of what works for producing tortoises able to survive in the wild, and in some cases, reproduce in the wild. True, most of this information has not been readily available. Captive bred records in zoological institutions illustrate problematic mortality. Although the information may be challenging to access, it appears good information has been available for years. In order to grow large animals, perhaps shortcuts have been taken by using readily available highly digestible, high energy diets rather than utilizing diets high in crude fiber which is effectively less energy dense. Obviously, there are other factors as well.


Hydration with growth is certainly essential. On the islands in their young tortoise pens, there are always trays of water, often containing rocks. I think the pre-repatriation areas have shallow masonry ponds. Other than use of a dark plywood box the first few days after hatching, I am not aware of high humidity hides or closed enclosures used in the Galapagos. Some outdoor pens do have hides. In our experience, when growing hatchlings indoors, the whole room/area has been kept warm and humid. Outside humidity is more varible.


Overall the Galapagos Islands are arid. There are seasonal areas of lush vegetation in some elevations on Santa Cruz. Larger tortoises may migrate to follow the seasonal peak vegetation at different elevations although smaller tortoises do not migrate. The larger tortoises around the rims of the Volcano Alcedo may catch moisture from evening dew during the dry season. When it does rain in the caldera, there are shallow ponds in which the tortoises congregate. Some of the islands are much more barren. On Espanol, the tortoises are likely completely dependent on the presence and density of Opuntia megasperma. J.P. Gibbs (2014) indicates “The cactus serves as a critical source of food, water, and shade for tortoises.” Lowland areas of Volcano Wolf are pretty dry with little green vegetation. The tortoises come out when it rains.


At our facility the rains herald the breeding season. It may be the tortoises also soak in mud or ponds to cool or to escape mosquitos, ticks, etc. Some will sleep with just their nostrils and a portion of the shell above the water surface. A tick has not been seen on our tortoises although they have been rarely found on our dogs. Those tortoises with opportunity to frequently soak here or in the Galapagos may get a form of yeast infection on their shell. The yeast can be suppressed/eradicated with the consistent use of petroleum jelly or coconut oil in the drier months. It can be cleaned up completely with frequent washings, particularly if animals are kept drier.

Keeping tortoises outdoors, primarily on grass with daily supplement of something, usually vegetables or produce, has not resulted in the symptom complex labeled “Rapid Growth Syndrome” (RGS). It is likely a tortoise with a hindgut full of grass can safely tolerate small quantities of most “treats”, produce, vegetables, etc., without danger of lactic acidosis due to too much readily digestible sugars.

I would liken aspects of this “RGS” complex to childhood and adolescent obesity continuing to adult obesity with all of its morbidity and increased mortality. The epidemic of childhood obesity is likely due to much more than too much sweetened beverages. It is a complex, multifactored disease process beyond the scope of this discussion. That is not to say the obese tortoises develop diabetes or metabolic syndrome. Obesity is clearly associated with all-source morbidity and mortality. (Executive Summary: Guidelines (2013) for the Management of Overweight and Obesity in Adults https://onlinelibrary.wiley.com/doi/pdf/10.1002/oby.20821)

(Recommendations for Prevention of Childhood Obesity https://www.researchgate.net/profil...od_Obesity/links/564ddcfa08aefe619b0e577f.pdf)

(Overweight and Obesity in Children and Adolescents https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4293641/pdf/JCRPE-6-129.pdf)

(Childhood obesity and adult morbidities https://blogs.commons.georgetown.ed...sity-and-adult-morbidities-Biro-Wien-2010.pdf)


Perhaps we should develop growth charts for each species and some form of BMI type chart? Several equations have been proposed. Could be as simple as Weight/SCL squared plotted against age. Other equations equating mass and size have been proposed for Aldabra and Galapagos tortoises. Examples of growth charts for humans:
Age_BMI boys.png age_weight boys.png

Obtaining weights in the field for large tortoises is problematic for a single investigator, likely making the above unrealistic for the giants.


Part of the tortoise mobility problem in “RGS” may be simply be similar to that seen with rapidly growing teenagers, particularly adolescent males with knee pain. In humans, Osgood-Schlatter disease is an inflammation of the area just below the knee where the patellar tendon attaches to the knee. It most often occurs in growth spurts. Physical activity makes it worse and it is more common in athletic participants. Likely the attachment of the patellar tendon with pull from the quadriceps to the tibial tubercle causes inflammation of the rapidly growing growth plate. This process or something similar, of course, is speculation in tortoises. If the growing giant tortoises are too heavy and unable to get their rear legs properly under their plastron for locomotion, additional weight gain apparently makes the situation worse and perhaps irreversible.


Some degree of rapid growth by itself may not be bad in the giants. Rapid growth at 10x that of tortoises grown on the islands has been documented to be associated with morbidity and mortality. (Comparative Study on the Growth of Juvenile Galapagos Giant Tortoises (Geochelone nigra) at the Charles Darwin Research Station (Galapagos Islands, Ecuador) and Zoo Zurich (Zurich, Switzerland) https://www.researchgate.net/profil...ich-Switzerland.pdf?origin=publication_detail). In zoological collections some of these giants suffer increased morbidity with some being unable to properly ambulate. The etiology of the “RGS” is multifactorial but rapid growth and weight gain is a major component.


From your notes, you have not found rapidly grown Sulcatas to have any problems which is Great! Are you able to quantitate your rapid growth rates as compared to wild sulcate growth rates?


Appreciate the information.
 

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Who is the author of this article? @Olddog is this your article or a reprint of someone else's work?
“Who is the author of this article? @Olddog is this your article or a reprint of someone else's work?”

I penned this somewhat over-simplified report in an effort to chronologically show a portion of the timeline of our knowledge of long-lived giant tortoise husbandry and hopefully illustrate some results of mistakes in same. The purpose was to share this information with other tortoise stewards such that they might review and formulate their own conclusions as might be applicable to species of interest. Based on your response, you clearly regard this effort misguided and inappropriate for this forum. Your objection is noted.

We should learn from the history of our predecessors as well as from our own actions. The publications chosen for this brief discussion share at least two criteria. They are felt to be representative of knowledge at the time and are available to readers with an internet connection without payment. It was hoped the interested reader would take the time to review each article in the context of the period and form their own conclusions. As time has progressed, our collective knowledgebase has improved. Despite these advances, husbandry issues continue. Unfortunately, in many cases, we appear to be continually reinventing the wheel. For instance, it would appear a number of individuals have felt a diet primarily of easily digested, relatively low crude fiber, soy and corn based “complete” pelleted diets from reputable suppliers supplemented with low crude fiber produce is an adequate and complete diet for our young hindgut fermenting giant tortoises. I disagree with same. This brief report attempted to illustrate some of the consequences of husbandry issues. That said, my personal retrospectoscope is still under daily development.


I respectfully agree and strongly disagree with some of your statements and will address them separately.

Tom: “Here is what I get from the article:

  1. Feeding a giant tortoise parrot food, shrimp meal, dog or cat food, fruit and grocery store greens causes problems.
  2. Housing a tortoise in too small of an enclosure causes problems.
Forgive my flippancy, but this is exactly what I and most other people have been harping on here at TFO for years. This is good info, but this is where I was more than 20 years ago.”


I think we can both agree that diets of 1983 and 1984 were fed more than 20 years ago.

What is impressive to me is Casares etal. (https://dokumen.tips/documents/mana...ne-elephantopus-and-geochelone-gigantean.html) recognized there was a problem, studied it, and made changes in an attempt to rectify the problem. They had a giant tortoise die and did a postmortem exam finding the visceral gout. How many of us always do a necropsy if an animal unexpectedly dies? I do not. I have done one necropsy on a 500 pound plus Galapagos tortoise simultaneously with preparation for taxidermy for a friend. The animal had been deteriorating in heart failure before death. Doing the necropsy involved a backhoe, A-frame, chain hoist, long arms and many, many hours. As the shell was not to be disturbed, everything had to be studied and recovered via orifices between plastron and carapace without the benefit of mechanical tools. Surprisingly the examination revealed the animal had a hypertrophic cardiomyopathy, a condition associated with sudden death in young human athletes. Today an ECHO cardiogram would likely have been diagnostic. I have sent several smaller tortoises with unexplained deaths to universities for necropsy, viral studies and other pathology over the period of years. Although we have usually learned earned what is not the cause of death, the results have usually been “normal dead tortoise”. I digress.

As you are aware, reptiles and birds convert nitrogenous waste to uric acid which is excreted as urates. Mammals convert same to creatinine which is passed in the urine. Excess uric acid may be deposited as crystals in joints (gout). Excess uric acid in reptiles in renal failure may crystalize in tissue. This was found to be the case in this mature Aldabra. This would suggest the tortoise was ingesting more purines from protein than its renal system could process.

Accordingly, the personnel at Zoo Zurich reviewed information from Aldabra and changed their husbandry in an effort to correct the problem. No less important, they also shared their information. They shared their failures and their plans to correct same. As the years have progressed and the knowledgebase grows, Zoo Zurich has continued to update its husbandry practices. I strongly applaud and appreciate the work involved to necropsy a giant tortoise and the efforts of the tortoise caretakers of the time.

Jarchow (http://www.deserttortoise.org/ocr_DTCdocs/1984Proceedings-OCR.pdf page 83-94) findings and recommendations of 1984 are certainly greater than 20 years old.


Tom: “Slow, or fast, growth has never been my goal. Healthy growth is what I am after. Faster than average growth is perfectly fine and does no harm as long as the animal is being fed the right foods, is being kept well hydrated, is getting UV and and is getting plenty of exercise in a large well-designed enclosure. @Markw84 and I, as well as many other people, tried the slow growth and food deprivation method. It doesn't solve the pyramiding issue and it can cause some other serious issues. Starving the tortoises to make up for other husbandry issues is not the way to go in my experience.”

I’m sure we can agree “Healthy growth” is the key and starvation is unacceptable.

The photos of deformities were from animals raised primarily on grass but with the addition of “parrot pellets” (which on analysis, are not unlike some of the commercial reptile diets currently marketed). For these animals, this was not “healthy” rapid growth. In those cases, lack of humidity or water was not a contributing factor. The D3 content of those pellets is now unknown.

Likewise, I’m sure we can agree premature death and morbidity are not “Healthy growth”. We can probably agree that animals grown with the ability to survive, grow, and reproduce in the native environment embody “Healthy growth”.

We may be able to agree zoological facilities using ISIS with ARKS, SPARKS, PM2000 and their ongoing permeations have recordkeeping and data management systems superior to those available to most hobbyist. They can access information on hundreds of animals from many institutions over many years. As AZA has an SSP program for Galapagos tortoises, virtually all specimens in AZA facilities are tracked. Less data is available for Aldabra tortoises. Data clearly shows husbandry practices of the past 30 plus years have not resulted in “Healthy growth” of young tortoises.

We may be able to agree that growth rates of 10 times that of wild animals may not be appropriate when those animals experience high morbidity and mortality. (I do not think we have good data to be able to determine how many times faster than wild growth we can safely grow giant tortoises, assuming all other husbandry conditions are ideal. Is 2 times, 3 times, 5 times or 7 times wild growth rates safe under ideal conditions?

There is considerable data on tortoises grown to survive repatriation to their native environment. For Aldabra tortoises there are likely in excess of 100,000 animals on Aldabra atoll. Whalers and others decimated populations on other islands. Translocation has been as simple as loading a number of adults or juveniles in large open outboard boats and moving them to another island with food and shade. No captive bred animals have been needed so we have no significant growth data for captive bred Aldabra tortoises for repatriation. On the Galapagos Islands, there has been need for captive raised animals for repatriation as the 1974 population was estimated at 14,000.

The growth and repatriation programs have been ongoing for many years. Starting in1965 eggs were brought from Pinzon for hatching and head-starting with the first group of 20 being repatriated in 1970 after they were big enough to likely avoid being eaten by introduced black rats. As mentioned previously, there was field research including behavioral studies to determine requirements for successful breeding, nesting and rearing. In the 1980’s experiments focused on the best incubation and rearing procedures with results being immediately incorporated into the program. In the 1980’s mortality of young tortoises at the center was 18% (4.2-31.8%). Average mortality of young tortoises at the center was reduced to <3%/year in the 90’s. Evaluations in the 90’s indicated a 68-77% survival of repatriated tortoises on Pinzon and at least 55% on Espanola. These represent high survival rates for repatriation but the natural habitat was intact on Pinzon. (Cayot, LJ The Restoration Of Giant Tortoise and Land Iguana Populations In Galapagos (Galapagos Research 65, p39-43 (http://aquaticcommons.org/21321/1/GR_65_p39-43.pdf) Now there have been over 5000 tortoises repatriated to Pinzon.

As of 2014, repatriation of hoodensisto Espanola has been more problematic largely due to the food and water supply. The feral goats have been eradicated. Unfortunately, 75 years of goats wiped out many of the younger cactus and limited adult arboreal prickly pear cactus (Opuntia magasperma) remain. The tortoises are dependent on this cactus for food, water and shade, especially in the dry periods. Cactus populations in the tortoise zones are low (1.7 juvenile cactus /ha, 0.4 subadult cactus/ha and 1 adult cactus /ha – totals 2142 juvenile cactus, 457 subadults and 1310 adult cacti. Tortoise density is directly correlated to cactus density and low in areas of woody plants alone. Approximately ½ of those tortoises released since 1975 were alive in 2014. They determined 5 year-old tortoises were best suited for this repatriation although survival for the first year was as low as 29% for several years. The chart represents 32 year recapture rates and first year survival rates.
Screen Shot 2018-08-26 at 9.37.17 AM.png

They felt 5-year-old tortoises best for repatriation in most cases although there is a size/age range dependent on the conditions in the area/island of repatriation.(Demographic Outcomes and Ecosystem Implications of Giant Tortoise Reintroduction to Espan ̃ola Island, Galapagos https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4211691/pdf/pone.0110742.pdf) In short, over the past 48 years, what is necessary in raising young tortoises capable of growing and surviving in the wild has been largely resolved.

Tom: “Forced slow growth due to food deprivation fails to address the other significant husbandry problems.”

We totally agree! I do not believe I indicated or recommended food deprivation for this purpose. I have advocated evidence-based, high crude fiber, relatively lower energy diets (as compared to manufactured tortoise pellets and produce) for safely raising giant tortoises.


Tom: "I appreciate the article and insight, but it seems the author, whoever it is, has a ways to go to catch up."

I am not certain what part of grass, browse, sun, water and exercise practiced the past 20 plus years you find objectionable, but you are certainly entitled to your opinion.


Tom: “A well hydrated tortoise kept in idyllic monsoon style conditions will grow 2 to 3 times faster than a clutch mate that is fed the same foods in the same quantities. Further, these faster growers will grow up to be healthy, structurally sound, reproducing animals further down the road, and have significantly less pyramiding. This is a key point that needs to be explained in this sort of discussion.”[

I would very much like to review your extensive data supporting these assertions in regard to giant tortoises.

:)
 
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Tom

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Based on your response, you clearly regard this effort misguided and inappropriate for this forum. Your objection is noted.

No. Quite the opposite. Not misguided or inappropriate in any way. I'm just saying you are very late to a party that has been going on for decades. I don't object at all. I'm happy one more person is spreading the word and trying to tell more people about this.

I'm well aware that much of the info given in the 80s and 90s was wrong. My point was that by the mid 90s I had raised enough tortoises and done enough experimentation to know that the info was wrong, and I've been crusading against this wrong info for more than 20 years now, and agree with you that this info was wrong long before I started speaking out against it.

We get one or two Galapagos Tortoise presentations each yer at the TTPG conference. I'm well aware of the head start work they've been doing there, and how they've discovered and solved many problems.

I see no need to continue this discussion or argue about any of this. I think we both agree, however we reached our conclusions, that:
  1. Feeding the correct foods is critical. Grasses, high fiber weeds, leaves and opuntia pads.
  2. Hydration is critical.
  3. Exercise in large, well designed enclosures is critical.
  4. Correct temperatures are critical.
  5. Grocery store lettuce, fruit, parrot food, monkey chow, dog food, etc… are not appropriate foods for giant tortoise species.
Where we may differ is in our concern about the rate of growth. I don't care or pay much attention to rate of growth as long as the above five points are well covered. Further, and I've pondered this a lot, I don't know how we could even begin to define "fast" or "slow" growth, and compared to what? Compared to life in the wild where they hide from predators or aggressive conspecifics, fight off a constant onslaught of disease and parasites and only have optimal conditions a few months of each year? I don't care about the rate of growth, because personal experience has taught me that as long as husbandry and living conditions are correct, growth rate doesn't matter. "RGS" is a problem when one or more of my five points that we agree on is not satisfied. "RGS" could only be caused by one or more of my five points not being satisfied.

If you want to discuss my multiple side-by-side experiments with groups of clutch mates raised with different variables such as primarily indoors, verses out doors all day, that would be a different thread.
 

Olddog

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having raised large dogs most all my life , your article rings familiar ……you won't get away with the nutritional and physical mistakes with big dogs as you will small dogs …..... something grows at that rate would have to be susceptible to orthopedic disorders , and as with dogs , it would be influenced by nutrition and exercise ............pyramiding I believe as markw says is not an orthopedic disorder it's the keratin deforming the growing bone , which is pliable ……… some of your distorted shells look like bone disorders ………….

I would think those deformities represent part of the Metabolic Bone Disease complex.
 

kingsley

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Thank you all !! I am in the process of raising two Galap Hatchlings now I am shaking in my Boots!!! LOL . So far they seem to be doing exceptional. I have a separate thread on them.
 

Kapidolo Farms

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@Olddog Do you have any awareness of the four Galops that had been or are maybe still at the Chelonian Research Institute? I was one of the keepers at the Philadelphia Zoo when they were bred there in the late 1990's. They were fed primarily grocery greens modified with Susan Donoghue's Spectrum Label of foods. She developed food supplements for tortoises that brought grocery greens into alignment with wild type diet in terms of protein, energy, fiber etc. I don't know if Peter kept up with those diets or not, later Susan stopped producing them, but by then those galops had gained much in size.

I'm not a fan of the chows or biscuits either, and feed much grocery greens out, but they are all brought to 'wild type' quality with higher fiber supplements and other things that help emulate better the wild type diet of most species.

I don't have Galops.
 

Olddog

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@Olddog Do you have any awareness of the four Galops that had been or are maybe still at the Chelonian Research Institute? I was one of the keepers at the Philadelphia Zoo when they were bred there in the late 1990's. They were fed primarily grocery greens modified with Susan Donoghue's Spectrum Label of foods. She developed food supplements for tortoises that brought grocery greens into alignment with wild type diet in terms of protein, energy, fiber etc. I don't know if Peter kept up with those diets or not, later Susan stopped producing them, but by then those galops had gained much in size.
.....

Hi,

I do not know the answer to your question. I last visited Peter and Sibille in Oviedo about eight years ago while delivering a carcass. Peter was very enthusiastic, having recently closed on the additional property and had started moving some specimens. One room in the new facility was dedicated to the Galapagos. At that time, he had no live Galapagos tortoises. He showed me where the “night house” had burned and tortoises had perished. I was under the impression they had had two tortoises (microphyes). We discussed sending him some youngsters, but he was not ready for same on the new property. He may have received tortoises at a later time? I think he and his daughter last visited the farm that year or the following year. As his disease progressed, we lost touch.


I think one of the microphyes from Philadelphia was transferred to Brownsville where one of our males resides. I understand some of the hatchlings are participating in a feed trial on a new product from Masuri under watchful observation.



In addition to crude fiber content, fiber length has an effect on GI transient time, etc. Do you feel fiber length should be a significant consideration in formulating diets for large tortoises?
 

Kapidolo Farms

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Hi, I do not know the answer to your question. I last visited Peter and Sibille in Oviedo about eight years ago while delivering a carcass. Peter was very enthusiastic, having recently closed on the additional property and had started moving some specimens. One room in the new facility was dedicated to the Galapagos. At that time, he had no live Galapagos tortoises. He showed me where the “night house” had burned and tortoises had perished. I was under the impression they had had two tortoises (microphyes). We discussed sending him some youngsters, but he was not ready for same on the new property. He may have received tortoises at a later time? I think he and his daughter last visited the farm that year or the following year. As his disease progressed, we lost touch.
I think one of the microphyes from Philadelphia was transferred to Brownsville where one of our males resides. I understand some of the hatchlings are participating in a feed trial on a new product from Masuri under watchful observation.

In addition to crude fiber content, fiber length has an effect on GI transient time, etc. Do you feel fiber length should be a significant consideration in formulating diets for large tortoises?
Hi, yes I absolutely agree fiber size/length is important. Because tortoises don't get much if any abdominal wall exercise to help with food motility it is all dependent on intestinal sphincter muscles, they need the fiber in the food to act on. Bigger intestines would need bigger fiber particles.
With broadleaf sources of fiber this ends up being self regulated by bite size. With grass they can end up with too much if they don't bite off the length of the blade. In either case as long as they are well hydrated I've not seen an issue.
I have lost very small neonate leopard tortoises by offering too much rehydrated grasses (from pellets) mixed in with grocery greens. The disproportional ingestion may have ended up having a constipation effect. I solved that problem by the use of broadleaf things like mulberry and hibiscus leaves which have a lignified vessel system, all cut to appropriate length by the act of biting off bits as they eat.
 

Olddog

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Hi, yes I absolutely agree fiber size/length is important. Because tortoises don't get much if any abdominal wall exercise to help with food motility it is all dependent on intestinal sphincter muscles, they need the fiber in the food to act on. Bigger intestines would need bigger fiber particles.
With broadleaf sources of fiber this ends up being self regulated by bite size. With grass they can end up with too much if they don't bite off the length of the blade. In either case as long as they are well hydrated I've not seen an issue.
I have lost very small neonate leopard tortoises by offering too much rehydrated grasses (from pellets) mixed in with grocery greens. The disproportional ingestion may have ended up having a constipation effect. I solved that problem by the use of broadleaf things like mulberry and hibiscus leaves which have a lignified vessel system, all cut to appropriate length by the act of biting off bits as they eat.

Agree, Thanks
 

Bee62

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An interesting discussion. I want to throw my 5 pence into it too.
Raising two aldabra tortoises makes me read a lot about this species. I found several interesting reports about the lack of iodine when these tortoises are kept in captivity in other parts of the world.
The lack of iodine cause thyroid problems. Tortoises can show symptoms like a goiter. The Chelonoidis nigra on the one video shows notable signs of thyroid problems and has a goiter ! The swollen parts of the body are signs for the sickness too ! This tortoise is not overweight but sick !
Aldabra and Galapagos tortoises are both species that are living on islands surrounded by water that contains iodine. In this natural environment the tortoises will suffer no deficit of iodine.
Kept not on an island and fed with wrong food, for example kale, spinach and broccoli causes a lack of iodine. All sorts of kale, spinach and broccoli contain goitrogens.
Read here what goitrogen can cause:

https://en.wikipedia.org/wiki/Goitrogen

When the thyroid of an animal or a human don`t work properly other organs of the body can be damaged too. When I read that some tortoises might have died because of heart weakness I think of thyroid problems.
Malfunction of the thyroid always cause heart problems !

I am sure that wrong food ( parrot food, dog food, all sorts of kale ), lack of calcium and not enough space to roam will cause deformed shells and bones ( MB ), but I am sure too that with the right food you cannot overfeed a growing tortoise.
When you keep a growing tortoise in the right conditions ( humidity, warmth, right food ) it will develop healthy and will grow as fast as the genetic code in his body cells are allowed to grow.
When we ask ourself as a keeper of giant tortoises what they need when they are kept in ( our ) captivity we should have a close look on their natural environment.
That`s why I will feed my tortoises a very tiny amount of iodine from time to time and they can eat as much as they want every day.
I will have a close look on warmth and humidity too. I am keeping them in an artificial micro climate in Germany but I can try to imitate the natural climate from where they come from.
Maybe in some years I can show here the result, if it was right or wrong what I have done.

Sabine
 

Olddog

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An interesting discussion. I want to throw my 5 pence into it too.
Raising two aldabra tortoises makes me read a lot about this species. I found several interesting reports about the lack of iodine when these tortoises are kept in captivity in other parts of the world.
The lack of iodine cause thyroid problems. Tortoises can show symptoms like a goiter. The Chelonoidis nigra on the one video shows notable signs of thyroid problems and has a goiter ! The swollen parts of the body are signs for the sickness too ! This tortoise is not overweight but sick !
Aldabra and Galapagos tortoises are both species that are living on islands surrounded by water that contains iodine. In this natural environment the tortoises will suffer no deficit of iodine.
Kept not on an island and fed with wrong food, for example kale, spinach and broccoli causes a lack of iodine. All sorts of kale, spinach and broccoli contain goitrogens.
Read here what goitrogen can cause:

https://en.wikipedia.org/wiki/Goitrogen

When the thyroid of an animal or a human don`t work properly other organs of the body can be damaged too. When I read that some tortoises might have died because of heart weakness I think of thyroid problems.
Malfunction of the thyroid always cause heart problems !

I am sure that wrong food ( parrot food, dog food, all sorts of kale ), lack of calcium and not enough space to roam will cause deformed shells and bones ( MB ), but I am sure too that with the right food you cannot overfeed a growing tortoise.
When you keep a growing tortoise in the right conditions ( humidity, warmth, right food ) it will develop healthy and will grow as fast as the genetic code in his body cells are allowed to grow.
When we ask ourself as a keeper of giant tortoises what they need when they are kept in ( our ) captivity we should have a close look on their natural environment.
That`s why I will feed my tortoises a very tiny amount of iodine from time to time and they can eat as much as they want every day.
I will have a close look on warmth and humidity too. I am keeping them in an artificial micro climate in Germany but I can try to imitate the natural climate from where they come from.
Maybe in some years I can show here the result, if it was right or wrong what I have done.

Sabine


You are quite correct in that an iodine deficiency or in certain circumstances, excess, can result in a goiter and thyroid dysfunction. In the US, there are areas of the country which have relatively low amounts of iodine in the soil such that pastures and crops are relatively low in iodine. Years ago, when foods were grown locally and before salt was iodinated, there were human and animal goiters caused by iodine deficiency with associated hypothyroidism. Florida soils have adequate iodine. According to the University of Florida, Florida pasture forages have been reported to be low or borderline low in P, Na, Cu, Se and Zn, with Ca, Mg and Co found to be borderline-to-deficient depending on location, season, forage species, and year. Cattle are usually given mineral supplements free choice as a low-cost measure to provide adequate mineral nutrition. Livestock feeds usually have mineral supplementation. This is mentioned as there has been Se deficiency related hypothyroidism reported in mammals. In addition to iodine from forage, our tortoise herd receives limited supplementation. Goitrogenic greens are not regularly fed. Although animals have been received with neck swelling, it has not materialized in animals raised on the farm. As most tortoises’ thyroid is located dorsal to the plastron, the thyroid may be enlarged but is not palpable most of the time. Swelling in a young tortoise’s lower neck may be also be thymic tissue.

Veterinary literature over the past 30 plus years repeatedly mentions an abnormal incidence of goiters in giant Aldabra and Galapagos tortoises. These statements may be antidotal. There are a few case reports of giant tortoise hypothroidism, one of which is linked at the end of this post.

If the mortalities associated with this “Rapid Growth Syndrome” were due to hypothyroidism, it would be easily treated with levothyroxine. Unfortunately, this is not the case.

In the examples of the two tortoises suffering consequences from “Rapid Growth Syndrome” discussed previously, thyroid studies and other chemistries had been drawn before they were ever sent here and as well as after they were here. These animals were euthyroid and chemistries were non-diagnostic. I understand they were raised on a pelleted diet, hay, grass and limited produce and vegetables. Additional dietary details are unknown to me. The tortoise which survived and improved has been on pasture with minimal supplementation and access to soaking areas. The underlying cardiomyopathy and presumed hepatic disease portend an uncertain future.

At the end of this post is a link to an older report regarding Florida raised Galapagos tortoises on grass and Masuri who underwent neck mass biopsies. Note this was the Masuri 5M21 rather than the newer low starch product. Why they had this thymus abnormality is unclear.

There have been many hundreds of Galapagos tortoises hatched in captivity in the US, most of which are no longer with us. Despite what some choose to believe, not all have been raised under improper husbandry conditions. Conditions of rapid growth seems to be the common denomination, often with a pelleted diet exceeding 5% of the diet by dry weight. Several captive bred species of tortoises may grow at 2-4 x the rate compared to that of wild grown animals without apparent problems. Captive bred Giant tortoises given nutritionally complete, easily digestible, relatively low fiber diets with more rapid gut transient times (as compared to grass fed tortoises) may grow as much as 10x as fast as those raised in their native habitat on grasses. No matter how much sun, exercise, humidity, etc., these rapidly growing animals receive, there appears to be some form of poorly understood differential growth with a “metabolic disconnect” suffered by many. A significant number of rapidly grown giant tortoises suffer complications associated with rapid growth including mobility issues, edema, morphological abnormalities, hepatic and cardiac disease.

Logically we would think we should be able to feed the giant tortoises good nutrition to satiety under ideal husbandry conditions and let them grow as fast as they will grow. Unfortunately, this has proven not to be the case due to excessive morbidity and mortality. Slow and steady growth with grass-based diets appear to work without the excess morbidity and mortality of the rapidly grown animals. Why this works is unknown and debatable. How fast can we safely grow the giants? The high fiber diets definitely appear much safer than the easily digestible nutritionally complete lower fiber diets. We know the gut transient times of grass-based diets is about three times slower than that of tortoises fed lettuce and produce. Does crude fiber amount and length play a significant or essential role? Have diets including significant amounts of commercial pellets resulted in a form of liver disease or is it secondary? Will the two, relatively new to market, “low starch” types of commercial tortoise pellets with higher crude fiber prove safer? Are the soy based componets of the pelletted diets appropriate for these animals?

There is not the extensive data on raising Aldabra hatchlings as there is on raising Galapagos hatchlings. Facilities that raise both tend to use the same diets. Growth rates on heavily populated Aldabra are a limited by population density and resources. There is good data on successfully growing Galapagos hatchlings. In excess of 7000 Galapagos hatchings have been raised to release size at the captive breeding centers on the islands with low mortality using a high fiber diet consisting primarily of cut stems and leaves of Xanthosoma sagittifoliumwith very low mortality. There have been more than a thousand hatchlings raised in this country. Many of these have been raised on nutritionally complete, easily digestible, relatively low fiber diets (pellets, produce and some hay or grass) with resultant high growth rates. Unfortunately, many of these hatchlings have subsequently perished or suffered health issues.

Each steward of these amazing giant tortoises will have to review the data, hopefully learn from the mistakes of others, and make their own husbandry decisions.



Gregory J. Fleming, Darryl J. Heard, Elizabeth W. Uhl, and Calvin M. Johnson (2004) Thymic Hyperplasia in Subadult Galapagos Tortoises, Geochelone nigra. Journal of Herpetological Medicine and Surgery: 2004, Vol. 14, No. 1, pp. 24-27.
http://www.jherpmedsurg.com/doi/pdf/10.5818/1529-9651.14.1.24



Terry M. Norton, Elliott R. Jacobson, Randolph Caligiuri and George V. Kollias (1989)
Medical Management of a Galapagos Tortoise (Geochelone elephantopus) with Hypothyroidism
Journal of Zoo and Wildlife MedicineVol. 20, No. 2 (Jun., 1989), pp. 212-216

(May view without charge)
https://www.jstor.org/stable/20094944?origin=JSTOR-pdf&seq=1#page_scan_tab_contents
 
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