From Majordomo@Concorde.ComSun Mar 26 07:01:46 1995 Date: Sun, 26 Mar 1995 09:57:38 -0500 From: Majordomo@Concorde.Com To: redram@best.com Subject: Majordomo results >>>> get scaly-info 012 Document Number: # 012 Date Entered: Thu Nov 10 18:12:51 EST 1994 (by ldaly@acs.bu.edu) Subject: Green Iguana Nutrition ------------------------------------------------------------------------------ Green Iguana Nutrition What to feed The Basics Iguanas are folivores, which means that in their natural habitat they dine almost exclusively on leaves. Unfortunately, the leaves that iguanas eat in the wild are not available to those of us who do not live in Central or South America. Therefore, we must offer our iguanas a great selection of vegetables that are available to us in order to insure that they obtain all of the nutrients essential to their survival. Offering only a few different varieties simply will not meet your iguana's nutritional requirements. Any old variety of vegetables, however, might not sustain your iguana for very long. Often times, foods of questionable nutritional value are chosen and pet iguanas wind up with illnesses stemming from malnutrition, usually from calcium deficiency. Therefore, we have some general guidelines to follow when picking out our iguanas' lunches at the grocery store. Again, these are very general guidelines, and the next section, The Specifics, must be considered as well when building your iguana's diet. It is the opinion of a growing number of herpetologists that the diets of both the juvenile iguana and the adult iguana should be the same, except perhaps in the area of vitamin and mineral supplementation. (See Vitamin and Calcium Supplementation section.) The basic diet should be comprised of the following portions of fruits and vegetables: 35% should consist of calcium rich vegetables 15% or less should consist of nutritious fruits 20% may consist of breads and grains, but this remains an optional portion of the diet 30% should consist of other nutritious vegetables In the Tables section of this booklet, you will find Table 1: Nutritional Content of Many Fruits and Vegetables, and Table 2: Calcium to Phosphorus Ratios. (See Calcium and Phosphorus section.) Both will be helpful when choosing foods to fill the above categories. Although you may not understand the significance of many of the vitamins and minerals listed, (a few will be talked about later in this section on nutrition) you will at least be able to tell which foods are high in calcium, and alternately, which seem to be deficient in most vitamins and minerals listed, such as iceberg lettuce. Also compare arrowhead to other vegetables - you will be able to tell which are nutritionally deficient. Foods largely deficient in nutrients should be avoided. The Specifics Keeping those basic guidelines in mind, there is some more very important information that you need to know. As you are probably aware, there are some foods that can cause problems in humans when eaten in excess. Not surprisingly, the same is true with iguanas. Humans are generally in charge of their own diets, and we tend to intake a wide variety of foods simply due to the fact that many different things are pleasing to our taste buds. Most people eat fruits and vegetables as well as meats, grains, and dairy products. Eating so many kinds of foods helps to insure that all of the nutritional requirements are met. In addition, many of the foods that we eat often, such as bread and milk, are usually fortified with vitamins. We may conclude that most of us receive all of the vitamins and minerals necessary to sustain life through the foods we eat. Iguanas, however, are strict vegetarians. Some human vegetarians experience health problems because they do not eat enough different kinds of vegetables regularly. Vitamin B12, for instance, is completely absent in most vegetables but is present in most meats. If a strict human vegetarian is to obtain this vitamin, he or she must take it in the form of a vitamin supplement. Iguanas, too, can be deprived of essential nutrients if they are limited to some particular group of low-nutrition vegetables that their owner has unwittingly chosen. Fortunately, much is known about the nutritional requirements of green iguanas, relative to many other reptiles, and you can sculpt your iguana's diet around the 5 factors that are listed below. They should all be considered with equal importance and not ignored. Nutritional deficiencies are common in iguanas because many iguana owners are unaware of the nutritional content of the foods that they are offering their pets. Sometimes, even a seemingly varied diet can be a poor one if the wrong vegetables are chosen. 1. Calcium and Phosphorus The food that you give your iguana, on average, should contain about twice as much calcium as phosphorus. In fact, the recommended ratio of calcium to phosphorus for green iguanas is somewhere between 1:1 and 2:1. (A 2:1 ratio indicates twice as much calcium as phosphorus, while a 1:1 ratio indicates the same amount of calcium as phosphorus. When we speak of this ratio, the calcium content is always written first, followed by the phosphorus content.) This ratio is very important for bone growth and maintenance, as well as for muscle contraction and other important bodily functions. Metabolic bone disease, as well as many other health problems, can be caused simply by ignoring this ratio for a short length of time. In addition, it should be noted that hypocalcemia (calcium deficiency) is much more common than hypercalcemia (excess calcium) in iguanas. This generally means that iguana owners tend to upset the Ca:P ratio by depriving their lizards calcium, not phosphorus. If you take a look at Table 1, you will see why. Only about one third of the foods listed contain as much calcium as phosphorus. When choosing foods for your iguana, try to stick to those foods that have at least a 1:1 ratio. In the Tables section you will also find Table 2: Calcium to Phosphorus Ratios. The items are listed by their ratios, in descending order. The information in this table has merely been excerpted from Table 1, but it has been included so that you can find the better food choices faster. The foods which contain a Ca:P ratio of less than 1:1 are included because you will probably find yourself using low calcium fruits or vegetables from time to time, and I wanted to give you an idea of just how calcium deficient many of these foods are. The portion sizes are not included in this table. Table 1 is a more complete table of food values, and you may refer to it for portion sizes. With the portion sizes in mind, you can actually calculate exactly how much calcium and phosphorus you are serving your iguana at each meal. Most iguana owners do not wish to do this chore, understandably! In fact, it is not usually necessary. What you must bear in mind, however, is the RATIO of the calcium and phosphorus contents. One cup of pineapple pieces, for example contains 11 mg of calcium and 11 mg of phosphorus. That is an 11:11, or 1:1, ratio. This means that any serving of pineapple, whether it be one cup or one whole pineapple, will contain this ratio of calcium to phosphorus. This allows you to at least approximate what Ca:P ratio is present in the foods your iguana is eating. For example, if one day you feed your iguana a diet consisting of pear, green beans, mustard greens, endive and prickly pear, you will notice in the table that they all have Ca:P ratios between 1.06:1 and 2.32:1, which is satisfactory. Therefore, your iguana's diet will contain a Ca:P ratio somewhere between those two. If you stick to the first 66 fruits and vegetables listed in the table, which are the ones with ratios of 1:1 or higher, you will have less chance of running into problems stemming from hypocalcemia. Do not stick to the very highest end of the table only, however, as a diet containing too much calcium can cause hardening of the soft tissues due to calcium deposits. This problem can be just as serious as calcium deficiency. I would also like to point out the importance of another nutrient, Vitamin D3, at this time. Vitamin D3 plays a crucial role in calcium absorption: your iguana will not be able to use the calcium it ingests if Vitamin D3 is not also present. Vitamin D3 can be obtained through exposure to natural sunlight (see Ultraviolet Light section,) and it is also found in the food your iguana eats. At the time of printing, there remained some doubt as to whether or not Vitamin D3 can actually be absorbed by iguanas when it is in the form of food or vitamin supplement, so exposure to natural sunlight may be even more important than we once thought. If you are serious about maintaining your iguana's health, please do not stop at the end of this nutrition section; rather, continue on through the general care section so you can learn about the importance of things such as ultraviolet light and temperature. This may all sound complicated at first, but with the help of the text and tables in this booklet, iguana ownership can remain a rewarding endeavor. 2. Oxalic Acid It is known among nutritionists that oxalic acid, a chemical found in plants of the genus Oxalis, binds with calcium to form calcium oxalate, an insoluble salt. This seemingly obscure fact is a much overlooked, but very important, point to address when tackling iguana nutrition. What that scientific jargon means is that when you or your iguanas eat food high in oxalic acid such as spinach, rhubarb, beet greens, or swiss chard, the oxalic acid binds with the calcium in these vegetables, rendering it unusable. In even simpler terms, eating any of those four vegetables in excess can cause calcium deficiencies. In humans, this may not be very important because most of us eat varied diets, not usually restricted to vegetables such as these. But because we humans are in charge of our pet iguanas' diets, and because they are strict vegetarians, it is not difficult to see how some iguanas might end up being fed a diet consisting largely of, for example, spinach, which actually has a high calcium to phosphorus ratio but still contains this nutrient antagonist, oxalic acid. Most people are unaware that this seemingly nutritious vegetable also contains this chemical which binds up that calcium and deems it unavailable. The lesson? Do not use spinach, rhubarb (which is actually considered to be toxic to iguanas; see Toxic Plants table,) beet greens, or swiss chard as staple items in your iguana's diet. Iguanas have limited space in their stomachs, so you may not want to waste it with unnecessary foods. My piece of advice is to offer these four foods in only very small quantities, if at all. Certainly, if the grocery store is out of your favored greens, one bag of spinach will not harm your iguana. But you must understand that you must not offer any of these foods on a daily basis, or even half of the time. Iguanas in captivity are notorious for developing metabolic bone disease, and it is speculated that the excessive feeding of these foods is one of the reasons for that. 3. The Cabbage Family Like oxalic acid-rich vegetables, all vegetables in the family brassica (the cabbage-like vegetables) should not be fed in excess. Cabbage, kale, bok-choi (Chinese cabbage,) broccoli, turnips, rutabaga, cauliflower, and brussels sprouts can all cause thyroid problems in iguanas (as well as humans) if too much is consumed. In short, (as I assume you've gotten an idea of how urgent all of this is by reading the previous few paragraphs,) do not use any of the eight aforementioned vegetables as staple items in your iguana's diet. They will cause metabolic problems eventually if fed in excess. 4. Tannins One last group of foods that is generally recognized by those of us who are concerned with iguana nutrition are foods that contain large amounts of tannin. Tannin binds protein, fights digestion by inhibiting key enzymes involved, and can also render iron and vitamin B12 unavailable. If served in excess, foods high in tannin can damage the liver. Foods that contain relatively large amount of tannin are spinach, carrots, bananas, grapes, lettuce, rhubarb (which is, once again, considered to be toxic to iguanas and should not be offered anyway,) and onions. 5. Cat and Dog Foods As was mentioned earlier, many herpetologists now believe that captive iguanas of all ages should be offered the same type of diet. It was once widely believed that juvenile iguanas needed more protein in their diets than adults. Thus, juvenile iguanas were offered foods such as commercial cat and dog food, insects, and cooked meats. Although we still recommend more vitamin supplementation (see Vitamin and Calcium Supplements section) for juvenile iguanas than adult iguanas, we no longer recommend offering increased protein to juveniles. Examination of the stomach contents of wild iguanas indicates that iguanas of all ages are folivores, and not omnivores as many used to believe. Certainly, your iguana may relish the high protein foods listed above. You may offer them occasionally, but only as treats. Iguanas are neither cats nor dogs, nor are they omnivores. Under no circumstances should these foods become a large part of your iguana's diet. Even most herpetologists who still recommend offering increased animal protein in juvenile diets agree that protein-rich foods should only comprise a very small portion of the diet - around 5% total. If you feed your iguana a balanced vegetable diet complete with vitamin and calcium supplements, it should live a healthy life without these extra foods. Many iguana owners like to give their lizards low-fat dog food as a treat every couple of weeks, which should be fine and not interfere with their normal diets. If you do this, please use the low-fat variety, and you might even want to avoid the beef flavors because beef is higher in fat than other meats. In addition, it is better to use dog food than cat food because dog food contains less protein. 6. Commercial Iguana Diets The manufacturers of commercial iguana diets claim that their products contain all of the nutrients essential to the survival of green iguanas. It is recommended by some veterinarians that offering one of these formulated diets, without too many supplemental vegetables (which would throw off the formula) should be fed to any iguana that will eat it. However, there are other veterinarians and herpetologists who have found that some iguanas that are given this diet exclusively develop illnesses due to dietary deficiencies within a year. In addition, almost all iguana owners report that their iguanas' stools become much harder when they are fed the commercial diets, and it is speculated by some herpetologists that any poop that is that hard might have the potential to become impacted within the iguana's digestive system and cause a detrimental blockage. The conclusion of many veterinarians and herpetologists is that commercial diets are very new and insufficient research and experimentation has been done with them. Naturally, no one wants to subject their own iguanas to lifelong experimentation with a food product that has endured such slanderous remarks since its release, so it may be quite a while before any real conclusions are drawn. My conclusion is that if you have some sitting around, feel free to use commercial iguana food products on those very infrequent days when you realize that you are all out of greens and really don't have time for a trip to the grocery store. But on a daily basis, offer your iguana what it instinctively eats in the wild: leafy green vegetables. And if you ever do offer your iguana the dry commercial food, do make sure that there is plenty of fresh water available because iguanas obtain most of the water they need from the vegetables they eat. Most commercial diets contain virtually no water at all. The Good Stuff The good news is that, believe it or not, there are still some vegetables left that won't harm your iguana. Collard greens, parsley, dandelion greens and mustard greens are some of the favored foods for iguanas among herpetoculturists. If you refer to Table 2, you will see that they all have calcium to phosphorus ratios over 1:1, and if you read the last few pages you know that none contain much oxalic acid or belong to the brassica family that tends to cause thyroid problems. In addition, they are all relatively high in many essential nutrients. The foods that are currently recognized as being the best choices for an iguana diet are listed below. Remember to avoid foods high in oxalic acid, such as spinach, rhubarb, beet greens and swiss chard, to avoid cabbage-like foods which can lead to thyroid problems, such as cabbage, bok-choi, kale, rutabaga, turnips, cauliflower, brussels sprouts, and broccoli and to try to stick with foods that have a calcium to phosphorus ratio of at least 1:1. You can certainly offer the undesirable foods in small amounts, intermittenly. But considering the wide variety of other vegetables available to us, it is best if you stay away from such problematic foods. Good foods for iguanas: green beans, carrot tops, orange squash, strawberries, raspberries, cantaloupe, figs (fresh or dried), parsley, collard greens, dandelion greens, escarole, mustard greens, turnip tops, watercress, sweet potatoes, kohlrabi, vegetable and bean sprouts, kidney beans (cooked and mashed), asparagus, mushrooms, bell peppers, okra, corn. Remember, just because a food item is on the above list does not mean that you can choose it plus just one or two other items and serve them only. The list is only of any use if you try to use all of the items on it. In addition, you might want to refer to Table 1 and Table 2 to verify their nutritional contents, including calcium and phosphorus ratios. You must still pick and choose which combinations are the best. It would be easy for you if I tried to offer to you a sample diet that seems perfectly balanced in its nutritional content, but that poses two problems: 1. we do not know exactly what constitutes a nutritionally balanced iguana diet 2. your iguana needs variety in its diet. Like humans, it will tire of the same old foods and want something new. So take a look at the above list, and take a look at Table 1 and Table 2. Use the knowledge you have just obtained about anti-nutrients and formulate your own iguana diets daily. Feel free to add nutritious items to the above list if they have been overlooked. One of my goals in writing this booklet is not only to force its readers to memorize by rote which foods contain what and which don't contain what, but to teach people how to formulate their own diets for their iguanas, based on the information I have given. I do not wish to prescribe a diet; rather, I wish to help you formulate your own. Vitamin and Calcium Supplements Despite our efforts to offer varied, nutritionally complete diets to our iguanas, iguanas still sometimes wind up with nutritional deficiencies. This is probably due to the fact that the foods that iguanas eat in the wild are simply not available to us. Their natural foods probably contain exactly what iguanas need to survive, while the foods available to us in the grocery store do not. Therefore, vitamin and mineral supplements have been created for reptiles. Because juveniles are such rapidly growing animals, it is generally recommended that they be given more supplement than their adult counterparts. As a general rule, mix in a small pinch of supplement at almost every feeding. For adults, a larger pinch two to three times a week should suffice. There are several supplement choices on the market, so you may not know which one(s) to choose at first. I recommend a complete multivitamin supplement, such as Reptivite' by Zoo Med. (The standard disclaimers apply: I am neither an employee nor spouse of an employee of Zoo Med.) It contains many vitamins, minerals and electrolytes, plus amino acids. In addition, it contains a Ca:P ratio of 2:1. It also has an innocuous odor and it lists the guaranteed analysis of its contents on the label. This is my multivitamin of choice, due to the advantages just listed. In addition to a basic vitamin supplement, you may want to add a calcium supplement. As mentioned throughout this booklet, the major nutritional problem found in green iguanas is calcium deficiency. Vitamin supplements such as Reptivite' tend to contain the proper Ca:P ratio, which is good in its own right, but does not help if the diet you are offering it with is calcium deficient. I recommend a calcium supplement that contains calcium only, or possibly calcium and vitamin D3 which may help in the absorption of calcium. Some products on the market which are labeled as calcium supplements also contain phosphorus and vitamins such as A, B, E and C. These are all essential vitamins, but they can be harmful if offered in excessive amounts. If you are already offering a seemingly complete diet, plus a vitamin supplement, the only other thing you really need to add is straight calcium. This can be obtained from some health food stores, (if you can only get it in tablet form it can be crushed), or you can use Rep-Cal' by Rep-Cal Research Labs. (Again, I am not an employee or spouse of an employee of Rep-Cal; it is merely my supplement of choice at this point in time.) It is phosphorus-free and contains only calcium and vitamin D3. Water Like most living systems on Earth, iguanas need water in order to survive. Iguanas can live for a long time without food, but will perish quickly if deprived of water. It is important that you provide a water bowl in your iguana's enclosure so that it may drink when it wishes to. It is also important to keep it clean. Iguanas often choose to defacate in their water bowl, and they also bathe in it if it is big enough. Considering the high temperatures that must be maintained in your iguana's habitat, (see Temperature section) the water bowl can become a breeding ground for bacteria. It is a good idea to change your iguana's water daily, plus whenever you see that it has been soiled. Many people comment that they never see their iguanas drinking from the water bowl. This is because most do it very infrequently. Vegetables are comprised of mostly water - above 90% in many cases. Thus, your iguana will obtain most of the water that it needs from its food. You must still provide a water source, however, as your iguana will still need more water than its food can provide. Your iguana will be especially thirsty on days that it hasn't eaten or on days that it has eaten dry food, (such as a commercial iguana diet,) so please do not neglect your iguana's water bowl on these occasions. When to feed As a general rule, iguanas should be fed on a daily basis. This is especially true in juvenile specimens. As your iguana matures, it will not grow as fast as it did when it was young, so it may not require as much food intake. (Relatively speaking, that is.) These lizards may be fed every other day if they do not seem to desire food daily. However, unlike some other species of lizards, iguanas do not seem to have a tendency toward obesity and can be fed essentially as much as they will eat. In addition, iguanas should be fed at what we consider to be lunchtime. After your iguana's light and heat sources turn on in the morning, it will need a couple of hours to 'warm up' before it is interested in food. 11AM would be a good time to feed your iguana. If you work or go to school during the day, you generally have two choices: feeding your iguana in the morning or in the evening. Although neither is a particularly great time, please choose the morning over the evening. In the wild, iguanas would be done with their daily routine by late afternoon. At least if you offer the food in the morning your iguana can choose to eat it later. If there is no food all day, your iguana may become stressed. Do monitor your iguana's physical appearance on a daily basis and note the appearance of its sides. There should not be pronounced flaps of skin running down the sides of your iguana. If there are, your iguana might not be getting enough food. Try offering it more at lunchtime. In addition, the base of your iguana's tail should always be round and plump, not emaciated looking. If a larger lunch does not seem to help your iguana's thin appearance, refer to the section of this booklet entitled Troubleshooting, which deals with some common problems in iguanas. Eating and seasons You will probably find that your iguana eats more in the summer months than in the winter. This is normal behavior. Even in the tropics cooler seasons exist, and at that time iguanas eat less. Some dedicated herpetoculturists provide 'seasons' for their reptiles by varying their light cycles and temperatures. Some snake owners actually allow their snakes a period of hibernation during the winter months. All of this is done to try to replicate the animals' natural environment, thereby creating a less stressful environment. So, if your iguana begins to eat less when autumn arrives, do not immediately despair. It is probably just the natural phenomenon. 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