Why measure UVB to manage Vitd3 p.synthesis ?

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Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Wed Jun 26, 2019 6:03 pm

This paper explains why it's more appropriate to measure UVB flux than to take UV-Index and try to make inferences on the amount of VitD3 photosynthesis is going to occur in the reptile's exposed skin while basking.
Image

Image

https://www.researchgate.net/publicatio ... radiometer

I chose to set up based on UVB flux , based on the ideal level of UVB flux for a bearded dragon being 180 to 200 microW UVB flux / sq cm. My Preference is to use a DIRECT measurement rather than an inferred one.
NB , I have one of each Solarmeters , Model 4.2 (UVA microW) , Model 6.2 (UVB microW) and Model 6.5 (UV-Index).
https://www.solarmeter.com/pdfs/compare-2017.pdf

Not that trying to infer the level of VitD3 synthesis from UV-Index readings is bad , but I follow the science rather than the crowd.
Note that the model 6.5 is tuned for mammalian vitD3 p.synthesis , not reptilian vitD3 p.synthesis.

Compare Model 6.5
Image
to Model 6.5R ( is repackaged Model 6.4 )
Image
Model 6.5 undercompensates , Model 6.5R overcompensates when comparing the meters calibrated responses.
Last edited by kingofnobbys on Wed Jun 26, 2019 7:35 pm, edited 7 times in total.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
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Re: Why measure UVB ?

Postby claudiusx » Wed Jun 26, 2019 6:58 pm

The article you posted does a good job of explaining the importance of the different wavelengths of uvb and how they contribute to d3 synthesis. And also why the solar meter 6.5s readout of uvi is desirable as it measures these different wavelengths and does the math for you and displays the result.

They are basically praising the 6.4 and mention the 6.5 is nice as you dont have to do the math you need to do with the 6.4.

Also, there is no science to how much uv exposure a dragon needs. Trust me, me and Francis have looked into it and looked into testing it ourselves but current blood tests for d3 in the blood are too difficult, expensive, and not to mention all over the place. You can test the same exact blood twice and get two different results. Clearly you can see how at this point in time, there is no science to how much exposure is needed as we have never tested dragons blood under differing levels of artificial uv exposure.

Not to mention, wild dragons are much different than captive bred hobby dragons. Hypos, trans, leatherbacks, silkies, these all are genetic mutations which would allow more uv to penetrate the skin. Especially compared to a dark spikey wild dragon who has much better sun protection.
That alone begs the ethics of using one recommendation for every situation.

Clearly, if a dragon has a mutation that affects the skin's ability to protect the body from harmful uv light, that dragon should be under lower conditions than a wild dragon, or even a normal.

I have a feeling that whenever someone gets the funding and the willingness to do so, we will find that we really dont need to be exposing our dragons to as much uv exposure as you have been suggesting.

Logically thinking (I dont know how long you've been in the hobby and I wont assume) for decades we used our t8 bulbs on top of our mesh tops and never did our dragons develop MBD or other bone issues. They were living long healthy lifes, other things considered. So, if it's obvious that uv exposure CAN be damaging, it only makes sense to only expose our dragons to the lowest level that still allows for adequate d3 synthesis. And this includes lower values for skin mutated genes.

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Re: Why measure UVB ?

Postby Aaradimian » Thu Jun 27, 2019 1:05 pm

So, if it's obvious that uv exposure CAN be damaging, it only makes sense to only expose our dragons to the lowest level that still allows for adequate d3 synthesis. And this includes lower values for skin mutated genes.


It would be nice to have solid data on the subject of metabolism vs. lighting, esp. with UV being ionizing. You only have to get toasted red on a hot day to realize that nature only goes so far to protect our skin, and while some lizards may be much better adapted to it, it illustrates that there's always the possibility of "too much". Semi-related, I found this in space science news today. Greater than around 30 gray of exposure to ionizing radiation and we're crispy critters, but this mold can handle hundreds!

https://phys.org/news/2019-06-space-sta ... -high.html
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Thu Jun 27, 2019 8:24 pm

So, if it's obvious that uv exposure CAN be damaging, it only makes sense to only expose our dragons to the lowest level that still allows for adequate d3 synthesis. And this includes lower values for skin mutated genes.


Bearded dragons have evolved over hundreds of millions of years to cope with routine exposure to extreme levels of UV in summer.
See this for some REAL UV-Index Data for a location central to the natural range of central bearded dragons
Image
source https://www.weather-atlas.com/en/austra ... e#uv_index & more details are available from BOM's site.
Image
and at the sounthern extreme of their natural range
Image

UV-Index 3 to 7 are winterlike levels of UV for central bearded dragons.

It's a mistake to assume the response of the bearded dragon's skin will be the same as that of a white or yellow skinned human or even that of a dark skinned human (who has adapted to cope with tropical sunlight / UV levels).
Another mistake is to assume UV-Index levels in the mid 40 deg N in summer in the USA are going to be as high as in the natural range of bearded dragons.

Plus bearded dragons have a neat evolutionary trick in their coping arsenal to deal with extreme UVI levels, they can adjust their skin pigments at will , not only to increase or decrease their skin's emissivity ( and how it absorbs heat ) , but how it absorbs UV .
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EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby claudiusx » Fri Jun 28, 2019 4:27 am

You're skipping over a few very valid points.

1. Captive bred dragons with skin mutations that affect how protected they are from uv.

2. For decades t8 bulbs over mesh has provided adequate d3 synthesis as dragons housed under these conditions wouldn't develop mbd, other proper husbandry considered.

Anything to say about these points or are you going to just skip over them again with random charts instead of actual discussion.

I don't understand how you can decide to use one part of their wild habitat as a basis for your thoughts but ignore others. For instance, you state that it's very dangerous for dragons to be offered a basking surface of near 110. But, areas where dragons live, the surface temp of the ground can easily get to the 130s+

So, using your logic of copying your UV recommendations from uvi levels, should we not offer a baking surface of 130 since it gets to that in their natural habitat?
Of course not , that's silly.
Just as silly as thinking we should be providing wild level uvi levels. Especially to much less adapt dragons.

A better chart would be average uvi levels of when dragons most commonly bask. It's been well documented that they seek shelter in the noon time. if not from the uv, definitely from the heat. So its misleading to include noon time uvi levels in the average as most dragons will usually avoid these noon time levels. Your chart would show much lower uvi averages if you took out the noon time numbers.

And remember CLIMATE DOES NOT EQUAL MICROCLIMATE. You could be getting a uvi reading of 7 out in the open, but where the dragon is basking could have a much lower uvi level. Whether that's because he's basking up in a tree, near a Bush, near a rock formation, etc. You can easily test this yourself by going outside with your 6.5 measuring the uvi, then dropping your uvi meter onto the grass and measuring again.

Either way, like I said in the first post. There is no science behind how much they need. Every chart in the world you produce won't solve the mystery either. No valid testing has been done to determine how much uv is needed. Everything else is just other people's guesses. Because no one knows. What we DO KNOW is that dragons have been thriving in captivity for decades with much weaker uv than you're suggesting to people now. So why risk damage when we KNOW lower SAFER uvi levels get the job done.

If you can agree that uv can be damaging (come on, this is a given) then you should also agree that we should only be providing them as much as they need, and not more. As you very quickly get to a point where more stops giving benefits, and starts causing issues.

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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Fri Jun 28, 2019 5:22 am

More strawman tactics eh.

Just because something was an accepted practice (driven by the fact that better UV sources were not available in the past) doesn't make these practices BEST PRACTICES.

Note also that dropping names with claims you've worked with these "notables" doesn't add one jot to your credibility , heck anyone can make these claims .
Such claims without supporting proof are worthless , ie your name as a contributer in a paper or report.

I've lived & worked for a few years in p.vitticepts territory and also holidayed on extended 4x4 camping safaris In most areas of their home range in all seasons since retiring.

My personal observations have been that hatchlings and juveniles and adult p.vitticept will be out basking literally soon as the sun is up and are frequently seen foraging and basking and guarding their territory all thought the day , only driven to take cover when the temperature gets up around 42 degC.
They have no choice as they are have to find their own food (insects , smaller reptiles , hatchling birds and leafy stuff (if it's not bene burnt off by heat and drought).

If you don't like the real world data , produce some real data that others can test that actually supports your argument for using very low (inferred) UV-Indexes as setpoints for the basking spot and warm zones for p.vitticepts as the guide rather than a directly measureable UVB flux .
Last edited by kingofnobbys on Fri Jun 28, 2019 6:13 am, edited 1 time in total.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
Gecko : Godzilla the hatchling GEHYRA GECKO (hatched May 2019)
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby claudiusx » Fri Jun 28, 2019 5:45 am

You still didn't comment on my two points at the top of my post.
Or any of the other points I made. You could at least try to discuss them instead of circumventing them with other comments.

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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Fri Jun 28, 2019 6:15 am

claudiusx wrote:You still didn't comment on my two points at the top of my post.
Or any of the other points I made. You could at least try to discuss them instead of circumventing them with other comments.

-Brandon


I don't see any good reason to do so.

All you've given are handwavy opinions and strawman arguments ==> you don't have a leg scientifically to stand on. .
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby claudiusx » Fri Jun 28, 2019 7:02 am

Ok lol.

Strong argument there.
Since all I'm trying to do is get you to actually discuss this topic as opposed to just posting up any chart you can find and calling it science, I'll copy over my thread from the other forum section on this site. That way, an actual discussion can occur on this website. You can feel free to comment on that thread if you actually want to debate the topic instead of telling everyone who doesn't agree with you that they are wrong.

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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Fri Jun 28, 2019 7:33 am

Go right ahead and do that.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
Gecko : Godzilla the hatchling GEHYRA GECKO (hatched May 2019)
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby claudiusx » Fri Jun 28, 2019 7:35 am

kingofnobbys wrote:Image
source https://www.weather-atlas.com/en/austra ... e#uv_index & more details are available from BOM's site.
Image
and at the sounthern extreme of their natural range
Image


Don't know where they got these charts as there is no source data provided, but this is directly from your governments website.
[Click image to enlarge]

Heres the link.
http://www.bom.gov.au/jsp/ncc/climate_averages/uv-index/index.jsp?period=an#maps
Additionally, you will see that in the drop down menu of your governments website on average solar uv index, that you can see the average for all months, and seasons. Do note that this is noon time averages only.
So, talk about a shakey leg to stand on. How can your charts show an average uv index of 12 in the month of January, when your governments site shows an average noon time level of 12-14? Your charts are false as you can't have an average of 12 if the only time it gets that high is for 1 hour of the day...

Would you like to provide a source for your charts that trumps your own governments data?

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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Fri Jun 28, 2019 8:20 am

If you bother to check (drill down into) the BOM data (available to anyone) that data is directly drawn from there.
http://www.bom.gov.au/uv/ shows how.
ie the data come from the metadata that is used to create this http://www.bom.gov.au/australia/meteye/
and
for summer av UV-Index
http://www.bom.gov.au/jsp/ncc/climate_a ... period=sum
Summer Average for Adelaide is UV-Index = 11 to 12.
Summer Average for Alice Springs is UV-Index = just shy of 14.

for winter av UV-Index
http://www.bom.gov.au/jsp/ncc/climate_a ... period=win
Winter Average for Adelaide is UV-Index = 3
Winter Average for Alice Springs is UV-Index = just shy of 6.
It will be obvious why I chose Alice Springs, Adelaide and Broken Hill as indicative locations in the natural range of P.Vitticepts.

Now regarding your "article" , viewtopic.php?f=6&t=249953&p=1894678&view=show#p1894678 , I don't see any hard scientific evidence cited there , just opinions and inferences , ie nothing additional to anything you've already claimed.

And I've already addressed the assumption that reptile skin response to UVB is not the same as human skin response to UVB (and even human skin types as a consequence of the amount of pigment respond different to each other too) , to claim reptile (p.vitticepts in particular skink responds most effectively in p.synthesis of VitD3 at UV-Index about 3 is a nonsense assumption that has zero scientific evidence (data) to support it. Human skin response to UVB is unlikely to be a good analog for P.Vitticepts skin response to UVB.
Last edited by kingofnobbys on Fri Jun 28, 2019 8:38 am, edited 2 times in total.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
Gecko : Godzilla the hatchling GEHYRA GECKO (hatched May 2019)
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby Aaradimian » Fri Jun 28, 2019 8:22 am

CX/KN: Putting aside the obvious love fest in this thread :lol: , here's a good breakdown of UV considerations from the NIH: https://www.ncbi.nlm.nih.gov/books/NBK401584/

Conveniently, they list Denver, CO in 1.3.1 Fig 3 (where I'm located). To CX's point about microclimate, this is especially pertinent here because I'm at "a mile high", but within an hour I can almost triple my altitude. According to this article, for every 300m, irradiance increases about 4%. Of course that altitude change comes with an adiabatic lapse rate of about 6*F per 1000 ft, so it's not really beardie friendly at 14,000 ft. Summers here are hot and dry, and my guys love being outside. Winters are not bad in Denver, but not suitable for them to be outside except snuggled against me in the folds of a jacket.

To KN's point about the equivalence (or lack there of), of human vs lizard skin, I completely agree. As seen in that article I posed about mold, biological systems are all over the map in terms of tolerance to various things. Tardigrades are masters of survival in conditions that would crisp human and beardie alike, for instance. It would be good to know what an optimal dose would be for beardies to keep them healthy. Just like there seems to be a lot of ambiguity about what is healthy sun exposure in humans, it'd be nice if there was a body of research we could hang our hats on when trying to advise people about best husbandry practices. "Get a Reptisun or Arcadia tube" is all well & good in that we have our own experiences to point to the fact that it does no obvious harm to use them, but it's sloppy work IMO.
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby kingofnobbys » Fri Jun 28, 2019 8:35 am

Aaradimian wrote:CX/KN: Putting aside the obvious love fest in this thread :lol: , here's a good breakdown of UV considerations from the NIH: https://www.ncbi.nlm.nih.gov/books/NBK401584/

Conveniently, they list Denver, CO in 1.3.1 Fig 3 (where I'm located). To CX's point about microclimate, this is especially pertinent here because I'm at "a mile high", but within an hour I can almost triple my altitude. According to this article, for every 300m, irradiance increases about 4%. Of course that altitude change comes with an adiabatic lapse rate of about 6*F per 1000 ft, so it's not really beardie friendly at 14,000 ft. Summers here are hot and dry, and my guys love being outside. Winters are not bad in Denver, but not suitable for them to be outside except snuggled against me in the folds of a jacket.

<<< True .
And also less atmosphere ==> less absorption of UVA , UVB and UVC by the atmosphere , hence at 14k feet altitude at any given latitude , the UV-Index will be significantly higher than at sea level at the same latitude.
I think I have a monogram that show how to calculate the increase in UV-Index with altitude stashed away somewhere, just can't pit my fingers on it ATM.



To KN's point about the equivalence (or lack there of), of human vs lizard skin, I completely agree. As seen in that article I posed about mold, biological systems are all over the map in terms of tolerance to various things. Tardigrades are masters of survival in conditions that would crisp human and beardie alike, for instance. It would be good to know what an optimal dose would be for beardies to keep them healthy. Just like there seems to be a lot of ambiguity about what is healthy sun exposure in humans, it'd be nice if there was a body of research we could hang our hats on when trying to advise people about best husbandry practices. "Get a Reptisun or Arcadia tube" is all well & good in that we have our own experiences to point to the fact that it does no obvious harm to use them, but it's sloppy work IMO.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : Fluffy - 4yr rescued lawnmowing accident victim 14Nov17.
Lucky - cat attack rescue, fatal SI RIP 21Jul2010.
Wriggles - rescued injured ,thought she was a big lizard, over 8 yrs old, RIP 2Feb16. .
Gecko : Godzilla the hatchling GEHYRA GECKO (hatched May 2019)
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Re: Why measure UVB to manage Vitd3 p.synthesis ?

Postby claudiusx » Fri Jun 28, 2019 8:41 am

kingofnobbys wrote:If you bother to check (drill down into) the BOM data (available to anyone) that data is directly drawn from there.
http://www.bom.gov.au/uv/ shows how.
ie the data come from the metadata that is used to create this http://www.bom.gov.au/australia/meteye/
and
for summer av UV-Index
http://www.bom.gov.au/jsp/ncc/climate_a ... period=sum
Summer Average for Adelaide is UV-Index = 11 to 12.
Summer Average for Alice Springs is UV-Index = just shy of 14.

Not correct. All those charts are for noon time averages, not daily averages. Clearly noon being the highest uvi levels, if you averaged the days uvi levels they would be much lower. So you're going to base your recommendation of 15 hours of uv exposure a day on only 1 hour of data from their wild habitat? An hour that they are usually not even in the sun for?

kingofnobbys wrote:Now regarding your "article" , viewtopic.php?f=6&t=249953&p=1894678&view=show#p1894678 , I don't see any hard scientific evidence cited there , just opinions and inferences , ie nothing additional to anything you've already claimed.

Don't humor yourself, I never called it an article. I clearly said I would copy my thread from the hidden forum over to the public.
So feel free to go there and discuss the points you want to discuss then if this topic is important to you.
kingofnobbys wrote:And I've already addressed the assumption that reptile skin response to UVB is not the same as human skin response to UVB to claim reptile (p.vitticepts in particular skink responds most effectively in p.synthesis of VitD3 at UV-Index about 3 is a nonsense assumption that has zero scientific evidence (data) to support it. Human skin response to UVB is unlikely to be a good analog for P.Vitticepts skin respond to UVB.

Ok, you didn't provide any science for this statement either. Your assumption that it's not similar, is just the same as someone elses assumption that it is similar. Although on this one, I'll take the doctor who has been studying reptiles and uv lighting for decades over yours, no offense of course :wink:

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