UVB and Calcium

[Yvonne G]

Will someone please write an easy to understand paragraph about UVB and calcium and how it works, how much, etc. directed towards a newer tortoise keeper. I'd like to post it as a sticky in the frequently asked questions section.

Thank you.

 

[Brian Perry]

Will someone please write an easy to understand paragraph about UVB and calcium and how it works, how much, etc. directed towards a newer tortoise keeper. I'd like to post it as a sticky in the frequently asked questions section.

Thank you.

Here’s what I recall. Within the skin of a range of species, including both humans an tortoises, is a Vitam D precursor called “7-Dehydrocholesterol.” When the skin is exposed to sunlight, this precursor is converted to Vitamin D3. Once you have circulating D3, you are in business. However, two more enzymatic activations are required to arrive at the final form of the molecule that will allow an animal to absorb calcium from the gut. There are two interesting things about this scenario. First, that calcium absorption should be evolutionarily tied to exposure to sunlight. This linkage is fun to ponder. Second, that this mechanism is so highly conserved among diverse species. With regard to this second point, we could simply conclude...if it ain’t broke, don’t fix it. The literature and at least one herp vet with whom I’ve discussed this top indicate that if the animal in question is receiving a calcium + D3 supplement, that no UVB lighting is required. There is some speculation that UV may have some additional, minor functions in various species, but there is nothing conclusive, beyond providing a somewhat more natural spectrum. If I have missed something, please pardon the oversight.

 

[Yvonne G]

Thank you, @Brian Perry . So let me ask, and if you don't know maybe someone else will know: Is there any difference between the vitamin D3 the tortoise eats in the supplement and making his own D3 by absorbing UVB - or maybe what I mean is can the body tell the difference between the two, and is one just as good as the other? @Will @Markw84 ???

 

[Yvonne G]

So, keeping in mind that I'm trying to put together a thread for the FAQ section, What do you all think of this:

I could show Brian's paragraph as the first paragraph in the thread, then the following that I took from Drs. Foster and Smith's site, with the adviso that if the member would rather go with a light then this applies:


In the wild, turtles and tortoises are exposed to ultraviolet light (UV) every day. Absolutely essential to their health and growth, UV plays a key role in the production of Vitamin D3, which is necessary in the absorption and metabolism of calcium, as well as other essential vitamins and minerals. Vitamin D3 deficiency can result in limited shell growth, metabolic bone disease, and often, a premature death. Supplying appropriate UV lighting in your pet's habitat is one of the many important responsibilities you carry as the owner of a turtle or tortoise.

To understand UV light more clearly, and the problems you may encounter when trying to supply it to your pet, you must first know that there are two main types: UVA and UVB. Your pet needs both, but he particularly needs UVB, the short wavelengths of light, for Vitamin D3 production. Exposure to UVA is also important for the activity level, feeding, and breeding in many species.

Each species of turtle/tortoise may have different Vitamin D requirements. The need for Vitamin D depends upon whether the turtle/tortoise is a land or water species, whether he is an herbivore (eats plants) or carnivore (eats meat), and upon his geographical origin (temperate or tropical). Depending upon the age of the animal, his species, and his diet, a combination of UVB light, calcium supplementation, and Vitamin D supplements may be needed. Research the needs of your particular pet to determine what will be best.

When using UVB light, there are several important things to remember:

• First, UVB cannot penetrate through glass, and it can even be partially blocked with fine mesh. Do not place a glass top over the cage between the bulb and the animal. If a mesh top is necessary to prevent escapes, select a type with larger openings. (Note: Quality UVB bulbs are specially made, so UVB can pass through their glass.)
• Second, UVB light from a bulb rapidly loses its intensity the farther away it is placed from your pet. UVB bulbs should generally be placed 12-15 inches above the animal, and no more than 18 inches.
• Next, when shopping for a UV bulb, it is important to consider the amount of UVB it produces. Research the UVB needs of your species before buying a bulb. Most species do well with a bulb that emits 3-5% UVB, left on for 10-12 hours per day.

Finally, UVB bulbs don't last forever. After several months of use, they start to decrease in output. Plan on replacing your bulb about every 10 months, more often for some brands. Keep in mind that this is one of the ongoing costs of keeping a turtle or tortoise.

 

[Brian Perry]

Thank you, @Brian Perry . So let me ask, and if you don't know maybe someone else will know: Is there any difference between the vitamin D3 the tortoise eats in the supplement and making his own D3 by absorbing UVB - or maybe what I mean is can the body tell the difference between the two, and is one just as good as the other? @Will @Markw84 ???

Hello Yvonne:
I just checked my calcium supplement jar. It says “cholecalciferol” and this is exactly the name given to D3 in vivo. I cannot think of any reason why the body could distinguish between the two.

 

[Brian Perry]

So, keeping in mind that I'm trying to put together a thread for the FAQ section, What do you all think of this:

I could show Brian's paragraph as the first paragraph in the thread, then the following that I took from Drs. Foster and Smith's site, with the adviso that if the member would rather go with a light then this applies:


In the wild, turtles and tortoises are exposed to ultraviolet light (UV) every day. Absolutely essential to their health and growth, UV plays a key role in the production of Vitamin D3, which is necessary in the absorption and metabolism of calcium, as well as other essential vitamins and minerals. Vitamin D3 deficiency can result in limited shell growth, metabolic bone disease, and often, a premature death. Supplying appropriate UV lighting in your pet's habitat is one of the many important responsibilities you carry as the owner of a turtle or tortoise.

To understand UV light more clearly, and the problems you may encounter when trying to supply it to your pet, you must first know that there are two main types: UVA and UVB. Your pet needs both, but he particularly needs UVB, the short wavelengths of light, for Vitamin D3 production. Exposure to UVA is also important for the activity level, feeding, and breeding in many species.

Each species of turtle/tortoise may have different Vitamin D requirements. The need for Vitamin D depends upon whether the turtle/tortoise is a land or water species, whether he is an herbivore (eats plants) or carnivore (eats meat), and upon his geographical origin (temperate or tropical). Depending upon the age of the animal, his species, and his diet, a combination of UVB light, calcium supplementation, and Vitamin D supplements may be needed. Research the needs of your particular pet to determine what will be best.

When using UVB light, there are several important things to remember:

• First, UVB cannot penetrate through glass, and it can even be partially blocked with fine mesh. Do not place a glass top over the cage between the bulb and the animal. If a mesh top is necessary to prevent escapes, select a type with larger openings. (Note: Quality UVB bulbs are specially made, so UVB can pass through their glass.)
• Second, UVB light from a bulb rapidly loses its intensity the farther away it is placed from your pet. UVB bulbs should generally be placed 12-15 inches above the animal, and no more than 18 inches.
• Next, when shopping for a UV bulb, it is important to consider the amount of UVB it produces. Research the UVB needs of your species before buying a bulb. Most species do well with a bulb that emits 3-5% UVB, left on for 10-12 hours per day.

Finally, UVB bulbs don't last forever. After several months of use, they start to decrease in output. Plan on replacing your bulb about every 10 months, more often for some brands. Keep in mind that this is one of the ongoing costs of keeping a turtle or tortoise.

Yvonne, one other thing. While I have a degree in this general area, I am not an authority with respect to D3 synthesis, calcium absorption, etc. There may be some subtle, yet important distinctions or facts...particularly, with respect to reptiles. I would recommend that you consult with others. You may want to speak with a faculty member at a university. Their information should be current.

 

[Yvonne G]

Thanks, Brian.

 

[Kapidolo Farms]

There are many tortoises that do not go out in the sun "everyday". Many have months with minimal exposure.

D3 also act as a hormone, some nutritionists call it a hormone and not a vitamin. Some of the hormonal roles are reproductive. Think about when those species that hibernate and brumate astaviate etc. bask the most and therefore would have elevated D3, same time the males become rapist and the females create eggs. There is a cycle to all this that goes well beyond daily sun exposure.

 

[SuzanneZ]

Here’s what I recall. Within the skin of a range of species, including both humans an tortoises, is a Vitam D precursor called “7-Dehydrocholesterol.” When the skin is exposed to sunlight, this precursor is converted to Vitamin D3. Once you have circulating D3, you are in business. However, two more enzymatic activations are required to arrive at the final form of the molecule that will allow an animal to absorb calcium from the gut. There are two interesting things about this scenario. First, that calcium absorption should be evolutionarily tied to exposure to sunlight. This linkage is fun to ponder. Second, that this mechanism is so highly conserved among diverse species. With regard to this second point, we could simply conclude...if it ain’t broke, don’t fix it. The literature and at least one herp vet with whom I’ve discussed this top indicate that if the animal in question is receiving a calcium + D3 supplement, that no UVB lighting is required. There is some speculation that UV may have some additional, minor functions in various species, but there is nothing conclusive, beyond providing a somewhat more natural spectrum. If I have missed something, please pardon the oversight.

Does this still stand?

 

[ZEROPILOT]

We desperately need a calcium/uvb sticky thread.
It's a very active question

 

[wellington]

I think you need something way less complicated than Brian's thread. Most members want a quick answer. For those that want more can click on the link
A single paragraph would be more beneficial.
You can then say, for further details, click on the link attached and then they would be able to read Brian's and everyone else's post.