Vitamins are organic substances which help regulate bodily functions. Acting as co-enzymes, vitamins aid the action of enzymes during the metabolism of dietary nutrients.
There are about a dozen major vitamins. A deficiency of any one will result in a serious deficiency disease.
Vitamins are only required in relatively small quantities. Nonetheless, they have a major effect on the body’s reproductive, digestive, nervous, and muscular systems. Vitamins also affect tissue growth and antibody production.
VITAMIN-A
Important to the condition of the skin and mucous membranes, eye (especially retinal) condition, biochemical and reproductive functions.
Plants contain carotene which is converted to true vitamin-A in the body. A deficiency is called hypovitaminosis.
VITAMIN-B COMPLEX
The B-complex vitamins are water-soluble and excesses are excreted in the urine. Click to read Why Soaking Tortoises Is Important for more information on urine and urates.
Vitamin B1, thiamine, regulates carbohydrate metabolism. Vitamin B2, riboflavin, is a co-enzyme in energy release. It interacts with vitamin B6 and vitamin B12.
Vitamin B3, niacin, is also crucial to energy metabolism and is often obtained by converting the amino-acid tryptophan. This process also requires the presence of thiamine, riboflavin, and pyridoxine.
Vitamin B6, pyridoxine, is involved in energy conversion from glycogen and the synthesis of haemoglobin and antibodies.
Vitamin B12 interacts with folic acid to govern the production of red blood cells. A deficiency causes pernicious anemia and neurological symptoms.
This vitamin is only produced within the gastrointestinal tract when various microorganisms act upon trace-level cobalt.
Deficiencies can occur after malabsorption syndrome or as a consequence of severe parasite infestations.
The B-complex is just that. A matrix of interacting and interdependent compounds.
VITAMIN-D
Sometimes called ‘the sunshine vitamin’, vitamin D is a fat-soluble vitamin. It is essential for the absorption and utilization of calcium and phosphorus. As such, it plays a major role in bone formation.
It can be obtained naturally. Ultraviolet light acts on sterols in the skin. Alternatively, it can be obtained orally by supplementation.
Virtually all specialist calcium/mineral supplements intended for reptile use contain vitamin D in enough quantity.
VITAMIN-C, E, and K
Vitamin C has many functions. It is present in almost all fruits and green vegetables. Therefore, deficiencies are extremely unlikely in tortoises.
Vitamin E is an antioxidant that works in conjunction with vitamins A and C.
A fat-soluble coagulation vitamin. Vitamin K is synthesized in the gut by bacterial action and is also found in plant foods.
It is especially abundant in green, leafy plants.
Minerals are quite different from vitamins and are both chemical regulators and construction materials. Calcium forms a major part of a tortoise’s body, more than any other mineral.
Calcium deficiency is also extremely common. A growing tortoise needs substantial quantities of this mineral to build its skeleton. Click to read about Growth and Pyramiding in Tortoises.
The building of healthy bone tissue is the result of many vitamins and minerals acting in cooperation with each other.
It is essential to note that calcium is poorly absorbed by the body. In contrast, phosphorus is readily absorbed. If a diet contains more phosphorus than calcium, the excess phosphorus will hinder calcium absorption. This prevents calcium from reaching the bone.
It is very easy to feed a diet too concentrated in phosphorus. This is because phosphorus is available in nearly every foodstuff. In contrast, calcium is relatively rare. We must knowingly choose calcium-bearing foods when designing diets for captive animals.
Calcium
Calcium and phosphorus together account for three-fourths of the mineral elements in the body. Five other elements account for most of the rest. It is important to note that their actions are interrelated; no one mineral can function without affecting the others.
The major role of calcium is to act in cooperation with phosphorus to build and keep bones. Calcium is essential for healthy blood and also helps to regulate the heartbeat.
In addition, calcium assists in the process of blood clotting. It helps prevent the accumulation of too much acid or too much alkali in the blood. It also plays a part in muscle growth, muscle contraction and nerve transmission.
Calcium aids in the body’s utilization of iron. It helps activate several enzymes, which are catalysts important in metabolism. Calcium also helps regulate the passage of nutrients in and out of cell walls.
Calcium absorption is very inefficient. Two factors affect absorption directly: the availability of calcium in the diet and the current body need. Unabsorbed calcium is excreted.
Certain substances interfere with the absorption of calcium.
When excessive amounts of fat combine with calcium, an insoluble compound is formed that cannot be absorbed. Other substances that can disrupt this process include oxalates and phytic acid.
Phosphorus
Phosphorus is the second most abundant mineral in the body. It functions along with calcium. A balance of calcium and phosphorus is needed for these minerals to be effectively used by the body.
Phosphorus plays an important part in almost every chemical reaction within the body. It is important in the utilization of carbohydrates, fats, and proteins for growth. It is crucial for the maintenance and repair of cells. It is also needed for the production of energy.
It aids in the transference of hereditary traits from parents to offspring. It is also necessary for proper skeletal growth, kidney function, and transference of nerve impulses.
If phosphorus content is high, extra calcium must be taken to maintain a proper balance. Phosphorus is available in a wide variety of foods, and further supplementation is not necessary.
Miscellaneous Elements
Calcium, chlorine, phosphorus, potassium, magnesium, sodium, and sulfur are present in relatively high amounts in the body tissues.
Other minerals are present in the most minute quantities but are essential for proper body functioning. Iron, copper, and fluorine are present in sufficient quantities in deep green leafy plants.
Iodine is needed to maintain a positive calcium balance. A multi-mineral mixture containing iodine should be provided. This is besides the supplementation of raw calcium.
In nature, tortoises obtain their calcium requirement in several ways.
The bulk of their requirement is typically supplied by consuming calcium-rich vegetation.
This vegetation typically grows on calcium-rich soils. This situation leads to plants that are rich in this mineral.
Tortoises also obtain some additional calcium in two ways. They consume sand or soil particles incidentally when feeding. They also deliberately seek out calcium-rich items in their environment, such as snail shells or sun-bleached bones.
Surprisingly, even desert environments often have extremely large snail populations.
It is not unusual to find hundreds of estivating snails per square meter. You can also find thousands of particles of broken snail shells in the same area.
Tortoises have been observed to seek these out and to consume them enthusiastically. They offer a concentrated, readily absorbed source of this vital mineral.
In most captive situations, the gross calcium content of the diet rarely, if ever, approaches that of wild diets.
The calcium-to-phosphorus ratio of captive diets is also typically far lower overall than is seen in the wild. Some typical examples include Plantago sp., with Ca:P ratios of above 20:1 and Opuntia sp., where Ca:P ratios can be as high as 78:1.
The typical diets adopted by many keepers are based on commercial salads and fruit. They often contain little calcium. These diets also have an excess of phosphorus.
One problem with relying solely on dietary choice is the presence of inhibiting chemicals in many plants. On the surface, these plants seem to offer good, or positive, calcium-to-phosphorus ratios. Still, they also contain chemicals that inhibit calcium uptake.
Mustard greens, turnip greens, kale, cabbage, bok choy, spinach, chard, and collard greens all fall into this category. One of the best-known examples of such an ‘anti-nutrient factor’ is oxalic acid. Another is phytic acid, found in high concentrations in peas, beans, and related legumes.
It is thus necessary to screen diets not only for gross calcium content and calcium-to-phosphorus ratio. It is also important to screen them to exclude reliance upon plants that contain high levels of these ‘anti-nutrients’. In practice, this is fairly difficult to achieve on an all-year-round basis.
Calcium supplements
Calcium is delivered in various forms, some of which are more readily absorbed and efficient than others.
Calcium supplements based on bone meal are inadvisable. They have inherently high phosphorus content, with 24% calcium and 12% phosphorus.
As most tortoise diets are already rich in phosphorus, supplementing with extra phosphorus is neither necessary nor recommended.
According to a recent review of calcium preparations, there are at least a dozen common calcium preparations. There are also hundreds of different formulations available.
Calcium carbonate is the most common preparation. Some others include tricalcium phosphate, dicalcium phosphate, and bone meal. Additional options are calcium citrate-malate, oyster shell, calcium lactate, and calcium gluconate.
These calcium preparations differ in a variety of ways. Calcium carbonate has the highest concentration of calcium by weight at 40%. Calcium citrate has 21% calcium by weight. Calcium phosphate has 8% calcium by weight.
Calcium carbonate has the highest concentration of calcium by weight. Yet, this form of calcium is relatively insoluble, especially at a neutral pH. In contrast, calcium citrate, although containing about half as much calcium by weight, is a more soluble form of calcium.
Certain preparations of calcium (e.g., bone meal, dolomite) contain contaminants like lead, aluminum, arsenic, mercury, and cadmium. Significant amounts were identified in calcium carbonate supplements labeled oyster shell, for example.
Chronic intake of these supplements poses an unnecessary risk. Most commercial calcium preparations are tested for heavy metal contamination.
In theory, excessively high intakes of calcium interfere with the absorption of other nutrients, like iron and zinc. Still, in chelonia, we are not aware that such effects have been demonstrated.
Other potential adverse effects of chronic intakes of high doses of calcium include Hypervitaminosis-D. Recent human studies indicate that increased intake of calcium does not increase the risk of kidney stones.
However, restricting dietary calcium may increase urinary excretion of oxalate. This can increase the risk of kidney stones. It may also cause bone developmental problems.
As a general rule, calcium carbonate is the preferred source for use as a routine supplement. It is both safe and effective. Limestone powder is available at a very low cost in bulk from agricultural feed merchants. It approaches calcium carbonate in efficiency.
In emergencies, when commercial supplements or limestone powders are not available, you can use human calcium tablets. Grind them into a fine powder. They can be applied to the food liberally. Note that some human calcium tablets may also contain vitamin D. However, this is usually in the form of D2. Reptiles require D3 instead.
These do contain useful amounts of calcium (up to 39% available Ca). They have been shown in human studies to help prevent osteoporosis in mammals. Nevertheless, it should be noted. For chelonian use, there are a number of potential drawbacks.
These include the fact that studies show that such eggshell material also contains hormone traces. These hormones can have unpredictable effects on tortoises. Any remaining egg membrane material can also contain antibiotic traces. It also signifies a potential reservoir for contamination by Salmonella organisms.
Turtle Blocks
One form of calcium supplement often sold in pet stores is known as “turtle blocks”. These are mostly made of Plaster of Paris (calcium sulfate hemihydrate) mixed with calcium carbonate, often in a 50-50 combination. Plaster of Paris itself holds almost no usable calcium and is merely used to adhere the block into shape.
Weight-for-weight, thus, “turtle blocks” contain 50% or less calcium carbonate, of which, in turn, only 40% is bioavailable. There are also concerns over heavy metal contamination in gypsum, from which Plaster of Paris is derived. This is not a form of calcium supplementation that we thus recommend.
On balance, the safest calcium supplements for routine use with captive tortoises are those that are calcium carbonate-based. They are also the most effective. They should be phosphorus-free ground calcium powder. preferably of commercial quality, either with or without added vitamin D3.
Lights
Vitamin D3 plays a pivotal role in bone formation. It allows the body to absorb calcium. It also maintains the proper balance of calcium and phosphorus. A tortoise will eat calcium all day long. Yet, without an adequate amount of vitamin D3, it can’t absorb it properly.
In nature, herbivorous tortoises acquire all of their vitamin D3 requirements through a chemical reaction in the skin. This occurs following exposure to the UV-B spectrum of sunlight. A compound is formed that is known as 7dehydroxycholesterol (this is sometimes also shortened to 7DCH or provitamin D).
This is converted, by means of temperature, to vitamin D proper. Both sufficient UV-B plus adequate basking temperatures must be available if this process is to function properly. This is one reason why the new UV-B heat lamps (self-ballasted Mercury Vapor lamps) are so good.
They provide both UV-B and the heat necessary to convert the 7DCH to a form that can ultimately be utilized by the calcium metabolism. A UV-B fluorescent tube alone will not do this. If such a tube is used, a separate source of basking heat is mandatory. Without an adequate source of heat, the conversion will not take place efficiently.
The extent to which you need to use a supplement containing vitamin D3 varies according to several factors. The main factors include how far north you are situated. Another critical aspect is the number of hours your animals are exposed to natural sunlight. It also depends on the type and intensity of UV-B supplemental lighting you employ.
Your animals can enjoy at least three or four hours outdoors if you live in an area where tortoises and turtles occur naturally. They should be in unfiltered sunlight each day. This will ensure they get enough sunlight daily. If so, you probably do not need to rely upon oral D3 supplements.
A calcium supplement alone should suffice. If you live in a northern, cloudy area, tortoises and turtles do not occur naturally there. If your animals’ outdoor time is restricted, it is recommended that you use a supplement regularly.
We would suggest three times per week as an absolute minimum. You may be able to rely on high output UV-B lamps if you have adequate basking facilities. These promote adequate D3 synthesis. Nonetheless, I would prefer to hedge my bets. I recommend supplementing with a calcium and D3 supplement orally at least twice a week.
Calcium and Vitamin D3 are certainly not the only components required to facilitate healthy bone development in tortoises and turtles:
• Magnesium is essential for proper calcium absorption and is an important mineral in the bone matrix. It has specific effects on the parathyroid hormone, which helps regulate proper calcium metabolism.
• Phosphorus is the second most prevalent mineral in bones. It makes up more than half the mass of bone mineral. Thus, the diet needs to have sufficient phosphorus in order to build healthy bones. For most tortoises and turtles, this is not a problem, as most vegetation is rich in this element.
The body takes calcium out of the bones when phosphorus levels in the blood are too high. Calcium binds with the phosphorus. This binding helps remove phosphorus from the bloodstream. Bones can become brittle or deformed as a result.
Many other micro trace elements are also important, including Manganese, Zinc, Boron, and Strontium. These may not be provided by a regular calcium or calcium with D3 supplement alone.
An appropriate and varied diet will certainly provide most of them. However, a wide-range mineral supplement can also be used. This ensures that they are present regularly. We would recommend that such a supplement be used no more than once weekly.
Cuttlebone
Cuttlebone is made of aragonite, that is, crystallized calcium carbonate. This mineral has a beautiful lattice shape, which explains its buoyancy and absorbent power.
Apart from this huge amount of calcium carbonate, cuttlefish shells include different essential trace elements. These elements have varying composition percentages in their composition.
Among the nutrients of cuttlebone, you can also find calcium phosphate.
It also contains calcium phosphate, sodium, magnesium, phosphorus, and other mineral salts.
Repcal
We are not sponsored by Repcal. But would love to be!
An exotic pet owner should supply cuttlebone, vitamin supplement, natural diet, and commercial foods. All of these are our weapons against Metabolic Bone Disease. This is an umbrella term referring to abnormalities of bones caused by a broad spectrum of disorders.
Rep-Cal is formulated to guarantee proper growth and health by providing full and balanced nutrition. Veterinarians recommend this food. It includes natural plant and fruit ingredients that tortoises love. It provides the 100% whole daily nutrition they need.
Rep-Cal Tortoise Food has been tested successfully by reptile veterinarians. It is fortified with optimal levels of vitamins and minerals like calcium. Vitamin D3 is included so no other food or supplements are required.
Bone
Yup, bone! The eating of bones, called osteophagy, is well known in turtles. The behavior has been recorded in several species kept in captivity.
Osteophagy has been regarded as a beneficial behavior to combat mineral deficiencies in animals.
Osteophagia practices have also been observed to be detrimental to the dental works of herbivores.
The pattern of wear on the cheek teeth of herbivores has been observed. It is akin to how herbivores hold and chew bones.
An interesting observational study of tortoises near St. George, Utah, found that the tortoises exclusively consume the Mojave Desert’s white stones composed of calcite (mostly calcium carbonate).
As opposed to the brown, grey, or other colored stones. The ingestion of these white stones is attributed to the deliberate intake of extra calcium.
These extra food sources are believed to offer not only calcium. They also offer other nutrients such as phosphorus, sodium, iron, copper, and selenium.
Besides desert plants, desert tortoises also consume vulture feces, which contain bones. They eat soil because its layers contain calcium. They also consume mammal hairs, feathers, and arthropods. Additionally, they ingest stones and bones of conspecifics, as well as snake and lizard skin castings.
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