How much outside time will allow elimination of mvb?

[leigti]

You may also find out that your MVB does not need to be replaced depending on what the meter says. Reading this thread has sparked my curiosity. Over the weekend I will check the UV levels throughout the day if I can. I live in South Eastern Washington state so I'm a little more south than you are but not that much more. My Russian tortoise spends got to figure all summer outside, June through August 24/7. And then during the day for at least a couple hours a few other months.

 

[leigti]

Question: According to your meter is morning and afternoon/evening sun "lacking" in UV when compared to mid day sun?

I know for sure that late in the afternoon like 4 PM there is not much UV. Maybe a one or possibly two. I have measured it at five at 1 PM. But I will Monitor it more this weekend since I'm going to be home. I'll write it down since I have the memory of a rock. The weather app on my iPhone lists the UV index. So if I was really lazy I guess I could look at that. So could the person who started this thread if they don't have a meter. I would still want to measure it where the enclosure is however. I will update later this weekend.

 

[WithLisa]

I live in South Eastern Washington state so I'm a little more south than you are but not that much more.

I think it's more important how high above sea level one lives than if it's a few degrees of latitude to the south or north.

 

[leigti]

I think it's more important how high above sea level one lives than if it's a few degrees of latitude to the south or north.

That could be. I'm only at 1000 feet here. I will see what the app says for some locations in Colorado that I have on it where my family lives. See what their index happens to be. If it ever gets sunny there again that is, they've had a ton of rain. I will also post that when I post the readings I get here.

 

[WithLisa]

I'm under 600 feet, that's why the UV index is so low, even though the climate is almost mediterranean.
As far as I know, vitamin D synthesis requires an index of at least 3.

 

[leigti]

That's good to know. I always wondered exactly what number is good. I guess it could depend on the type of tortoise also I think the tortoise in question on this thread is a Russian, so was mine.

 

[Tom]

As far as I know, vitamin D synthesis requires an index of at least 3.

What do you base this on? Frances, a UV researcher that I had the pleasure of conversing with, made it seem like this is one of the bits of info that is not known yet. Can they synthesize at a UV index of 1 or 2? Is there a minimum UV threshold that must be crossed? I've also read that temperature is a factor, in that the skin needs to be warm enough for D3 synthesis to take place.

As Mike pointed out, many tortoise in warmer climates like his and mine tend to avoid the mid day sun and only bask during the hours that those UV numbers are very low or absent. My tortoises will sometimes bask in the evening sun trying to get those last few warming rays and the UV meter says 0 or 0.1 at those times. Sulcatas living in Phoenix, AZ will hardly come out during the day in summer. Certainly not mid day.

 

[WithLisa]

What do you base this on?

I was taught in university that humans need an UV index above 3 (also depends on skin colour,...), but I never researched that topic. Maybe that information is not up-to-date anymore.

 

[Tom]

I was taught in university that humans need an UV index above 3 (also depends on skin colour,...), but I never researched that topic. Maybe that information is not up-to-date anymore.

It may be true. I don't know. I asked because I was looking to learn more on the subject.

I don't know of anyone more up to date than Frances, and she indicated that these details are not know for tortoises.

In my own mind, with no data to back it up at all, it seems illogical that a human or a tortoise could sit in the sun all day with a UV rating of 2.9, and get absolutely no UV benefit, but as soon as the number climbs to 3.0, different things begin to happen. See what I'm saying?

Given the steep curve of how the UV levels go up and down each day and given how our tortoises avoid the mid day sun a lot during warmer weather, I wonder about theses things.

 

[WithLisa]

I just looked it up in a biology book, it only said that ex vivo experiments showed that for example skin type 2 needs an UVB minimum of 18-20mJ/cm² for the synthesis to start, but there was no explanation.
Who knows, the human body is still a big mystery to us and the tortoise body even more...

But since the natural habitats of tortoises are hot with lots of UV, maybe it's an instinctive behaviour to avoid the dangerous mid day sun?

 

[leigti]

That could be. My tortoise doesn't seem to like to be out in the midday sun either. Even if it's not very warm. She seems to prefer cooler temperatures.

 

[Yvonne G]

This might be apples and oranges, but my daughter's doctor told her she needed more d3, as she is calcium deficient. She told him she spent most of her days outside in the sun working in the yard (she's very tan too). He told her she still needs to supplement d3.

I don't understand. This, to me, does not compute.

 

[leigti]

That doesn't make any sense. The average person only requires 15 minutes of sunlight a day to get adequate D3 levels. I have heard that this recent obsession with D3 levels is a little overblown. I don't know though, I'm not a doctor. I don't know enough about it to be able to apply it to tortoises.

 

[leigti]

@mini_max @Tom here is my extremely unscientific monitoring of the UV index ratings The last three days here at 1000 feet in Washington state and in Colorado at 5000 feet. I used my solar meter 6.5 here as well as the weather app on my phone and I recorded what the weather app said for Colorado. I also listed what the skies were sunny, partly cloudy etc. I stood in basically the same spot next to my tortoise pen. It is interesting how sometimes the app and the meter don't have anywhere near the same readings. And how sometimes even cloudy weather has a higher UV index listed at the higher altitude. I realize that it is one hour later in Colorado but I couldn't keep organized enough to worry about time zones. I don't know if this helps at all but it's kind of interesting. I hope you can read my crappy handwriting.

 

[Tidgy's Dad]

To get back to basics, I think just two or three hours of sunlight a week should be adequate, but as much as you can give is good, as long as the tortoise has shade and a hide to get out of the sun when it's too hot.
Even a little sunlight seems to be better than many uvb bulbs.

 

[Tom]

This might be apples and oranges, but my daughter's doctor told her she needed more d3, as she is calcium deficient. She told him she spent most of her days outside in the sun working in the yard (she's very tan too). He told her she still needs to supplement d3.

I don't understand. This, to me, does not compute.

Seems to me that she needs more calcium, not more D3. Did this Dr. draw her blood and check D3 levels?