I am trying to get my head around UVB light.

I have read the Internet material - a lot of it at least.
It seems to consist of :
a. self interested claims by companies producing reptile products
b. similar claims by zoos sponsored by such companies
c. straight forward assertions by hobbyists with no real way of measuring the truth of their beliefs
d. scientific comment which is largely incomprehensible and often non committal

It is clear that exposure to UVB light is necessary.
It is clear that this type of light is blocked by glass.
It is clear that sunlight does not have to mean blazing hot full sun - UVB light also shines down into dense rainforest.

It is unclear which type of lighting best delivers the necessary UVB, but obviously most people have an opinion and each situation - breed of reptile, dimensions of enclosure, positioning of light, length of exposure, heat or decorative requirements of the light source etc., all influence the choice.

It is clear that reptiles vary in their ability to utilise UVB light, so that thick skinned species such as Bearded Dragons need to bask for lengthy periods in the middle of the day, while thin skinned geckos can satisfy their needs in the brief periods of dull light at dusk and dawn. Both extremes, however, require UVB exposure.

The majority of articles indicate that snakes do not require exposure to UVB light because they get the predigested calcium their bodies need from the livers of the birds and mammals they eat.
My question here is:
If that is true, surely it would apply equally to lizards?
Monitors and skinks will accept minced meat which could include minced chicken livers or calf liver (both readily available). I can think of ways to ensure my dragons also eat liver as part of their diet.
Will the inclusion of liver in the diet of my lizards obviate the need for UVB lighting, or at least improve their chances of getting enough useable calcium?

Not being a vet I couldnt say weather feeder the likes of liver to lizards would satisfy the need for calcium or not, but bare in mind that exposure to uv is nessesary for vitamin d which itself is needed to absorb/bind calcium for digestion if im not wrong. (We need a vet onboard! )
That said, I dont trust any uv lighting to to do the job of sunlight, you simply cannot beat nature. I beleive a good few hours outdoors, even on a cloudy day, provides far more uv exposure than 12-16 hrs of artificial.
for monitors, I assume the same would apply as in snakes, that they can use avail calcium from food, but other species like beardys, wouldnt be getting much in the way of animal bone/flesh/organs, excepting from eating other lizards.
If you could find any good articles about this please post them up.
I am much intrested in this kind of thing.
cheers Inny

A very good site is:

http://www.uvguide.co.uk/

When I first read this material a few months ago I simply gave up.
It was all too complicated.

The best conclusion I could come to was that most "reptile" lights were a con and that I was just as well off using the NEC T10 Blacklight at a fraction of the cost of any "named" varieties and replacing them once a year. ( I have limited myself to fluorescent tubes because the idea of 25 spot or flood lights in a room would wake me up at night with imaginary fire alarm noises.)
It seems to me that provided I set up the furniture in each cage so as to encourage the lizards to lie at about 4" from the light they should be fine.

If, like me, you find all the test data too complicated and depressing, then the site does at least provide an easy to follow explanation of the nature of UV light, how it is used by the reptile and how much is needed.

It doesn't address my question about feeding liver though.

Im assuming some fat content in liver and the like, which like pinkies, cant be good too often. Ours get about 70% insect and 30% veg, some fruit , occasional pinkies, dog food rarely, various flowers, dandeline heads, rose petals, etc.
I dont use any alledged uv lighting at all, only standard mini flouros for photoperiod, purple globes for heating, which arnt too bright at night, like dim moonlight.
I address the calcium question by dusting meals with rep-cal and giving them as much unfiltered daylight/sunlight as possible.
Ive not encountered any metabolic bone disorders or anything.

Providing filtered sunlight, presumeably by putting them outside each day for a while sounds great for a pet Bearded Dragon or Bluetongue, but is not practical for a larger collection of small skinks, dragons and monitors.
When you say you've had no MBD problems, does that include lizards raised from birth?

"Ultraviolet Light and Life" an article by Lindsay Hazley, is an extrapolation from his Tuatara studies to the incidence of SIDS in babies, and has almost nothing to do with reptiles, but in passing raises some interesting points briefly.(http://www.reptileuvinfo.com/document-list.php):

1. UV light is most critical for newly hatched and juvenile lizards and less relevant to mature adults. ( Rearing losses went from 50 - 80% mortality rate with no special UVB lighting to 0%)
2. Dietary supplements had little or no effect.

As I understand it:
Vitamin eaten by the reptile is located in the skin where exposure to certain UVB wavelengths trigger photo-biosynthesis creating, in the liver, a Vitamin D3, which is needed to metabolise calcium.

Providing extra calcium without the means to convert it would seem a waste of time.
Another article on the above site, "Hypervitaminosis in Green Iguanas", (Dial up warning 1.85Mb) suggests that Vitamin D supplements are dangerous.

See what I mean about this material on the Internet being depressing!

Found that vet yet, Inny?

Yup, no instances of MBD in any of the lizards ive raised from birth/hatch.

I suppose alot would depend on time of day you 'sun' them aswell, since at various times the uv must travel further through the atmosphere to reach the ground/lizard, ie afternoon. Im guessing it would be stronger mid morning/midday?
how do find the t-10 blacklight? do you think its useful?

I've got 4' NEC T10s over all my enclosures together with either a normal tube in those with no plants, or a Growlux tube over tanks with plants.
Who knows if they are any good? Tests on this site suggest that, at less than a quarter the price, they are as effective at 18" as the most expensive specialist reptile lights are at 6":
http://www.reptilesdownunder.com/reptile/e...htingtestsa.php

I agree that a few hours of sunlight would be far better than hours of artificial light, but I've got Central Netted dragons, Painted dragons, Crested dragons, Angleheaded dragons and several types of skinks and pigmy monitors for which that just isn't practical.

Note: In case anyone has trouble locating these lights - NEC Blacklight UVB tube
Wholesale supplier in Brisbane is "Nelson".
The 4ft tube is known as FL40 SBL with the order code "M140". (From this your local lighting store should be able to source other sizes.)

What sort of set up do you use to give your hatchlings sunlight. Presumeably you don't just take them out on the lawn with you for several hours a couple of times a week?
You are raising them successfully (no MBD) without artificial UVB light, only supplementary calcium feeds in the form of Reptical powder.
How,
how much,
and how often are they exposed to sunlight?

I use a soft mesh enclosure and give as often as possible natural light. Since im a home Dad I have plenty of time and opportunity. Days like today (cloudy) the've been out all day (about 7.5 hrs) . At minimum, 4 hrs each a week. Every 2nd feed is dusted with reptical & repti-min.
I understand its not easy with a large collection, however Ive seen some excellent setups with this in mind, utilising a timbre frame of 8-10 ft x 3ft, x 3ft on legs, covered with light emitting shade cloth, that allows uvb/uva.
Animals are transfereed to these, there are separate partitions for various species, each with an access door.
the whole thing is positioned to allow shade at all times aswell as sun.
Im thinking of designing a similar thing myself shortly, as I currently use fine cages, its a real pain giving them time out.

P.s Do you have a link for the Nec t-10's? Im looking for a display page with specs etc, I havent been able to find one to date.

That sounds like an excellent setup for juvies, particularly as shaded sunlight is apparently all that is needed, not direct sun.
I don't have specs for the NEC T10 and wouldn't understand them if I did. If you phoned Nelson they could give you what you need, presumeably. then you can interpret it for me.

Lol, I have a very hard time interprating that stuff myself mate!

Ill google 'Nelson'

Google "Yellow Pages" and give them a phone call. The computer can only manage so much.

I read a few science papers. And bascially when it comes to lizards, the UVA/UVB light scenario is not bogus. One researcher tested with and without and the ones without had severe problems, some even dying (he tested beardies and some American lizard).
I will try and track down the papers, but I don't think they are on the net anywhere, just in science journals.

Oh, one more thing: a few hours outside of course is the most preferable - I believe the figure reached was something like 4 hours a week.

Also, when it comes to snakes, I don't think they need it as much, but it does improve their bone growth marginally over time.