tortoisetrustforum.org

Humidity and Pyrmiding on the Sulcata tortoise Dr. Sue Donahue
On a paper published by nutritionists at the University of Veterinary Medicine in Vienna
http://www.megaray.co.uk/downloads/humi ... ortois.pdf

I don’t think this trial has been discussed on here before, the link is from the information page of the above web site.
In an area that contains useful articles on research conducted in providing animals with a source of good quality UV
I don’t really understand their thinking on putting this link in, as it looks like all the tortoises on the trial had eccess to a Reptisun
5.0 by ZooMed and having a lack of good quality UV light was never part of the trial. The Sulcata’s that they found to
have pyramiding would also have had a good source of UV-B.

What ever the results are of this trial letting people think it’s OK to feed 30% protein dry pellet food to torts must be wrong.

Anyway the authors conclude that a hide of 100% humidity should be available to tortoises at all times to prevent pyramiding.

I think pretty much everything in this paper goes against what the Tortoise Trust recommend & it's a pity they have no biological
theories to help explain the results.

Thanks Matt, I have just read the article,

I had read before that humidity plays a role in well being and development. I know that torts will pee in dry burrows to increase humidity. I thought that was why we bathed tortoises on a regular basis to ensure good hydration overall as well as to help remove toxins. I think in a captive and relativity small enclosure High humidity would cause major health issues. Its not helpful at all to the small keeper and could really misdirect owners.

And the diet they have used is as you say not helpful at all. Sulcata may have high tolerences to protien than others. Not many people keep sullys, I think they should have used a species more akin to what people keep if they are trying to help Tortoise owners with the research...

Just my laymans thoughts
Gordi

That is not a "new trial" it is the original, highly defective, "study" published in 2003. Susan Donoghue had no part in it - she is simply reporting it.

There are so many defects in the methodology that it would take pages to list them. I'll restrict myself to two examples:

The most striking criticism of the data cited in their paper “Influence of environmental humidity and dietary protein on pyramidal growth of carapaces in African Spurred tortoises (Geochelone sulcata)” is that the bands of experimental humidity employed are so profoundly overlapping and are of of such wide individual range. The terminology used is also contradictory in the extreme. For example, they define what they term “dry environmental conditions” as consisting of the ranges “24.3-57.8 % and 30.6-74.8% relative humidity”. They then go on to define “humid conditions” as comprising “45-99% relative humidity”. It is difficult to know what to make of this, when a measured relative humidity of 45% is described as “humid” in one sentence and then classed as “dry” in another.

It is also the case that very few ecologists or geographers would normally accept a maximum relative humidity of 74.8% as in any way representing dry conditions, or a minimum of 45% as representing humid conditions. The use of such inconsistent and erratic definitions applied to the measured relative humidities must therefore give rise to serious concern and further confuses the earlier claims made in respect of “dryness” or “humid” conditions allegedly experienced in natural habitats.

There are a number of other serious methodological criticisms of this study that can be made, including the failure to adequate monitor and regulate actual calcium intake for the duration of the experiment, which would appear to have been highly variable and subject to individual preference (loose cuttlefish bone was provided in each enclosure and a tortoise could consume as much – or as little – of this as it preferred). Given that calcium intake and overal Ca:P balance is such a critical factor in bone development, the lack of control here is very worrying from the point of overall experimental validity.

I'd also point out the stark, fatal fact that really sinks these "conclusions" beyond any hope of salvage is that if indeed juvenile tortoises really did require "humid microclimates" offering "100% relative humidity" to grow properly every wild T. graeca graeca on the planet would look like the Giza Pyramids incarnate - because they don't get it in the wild. Period. Neither do G. sulcata. Neither, to my knowledge, does any other Mediterranean tortoise.

Andy

Sorry I must of got new from "just been published" and I missed the obvious "One paper published 15 years ago suggested | environmental humidity may play a role in pyramidal growth | (Weser, 1988,"

DOH

Well it was new to me and Gordi

Sorry you had to waste time on such a long post & thanks for explaining some of the flaws in the trial.
Well you can see why people get the idea that they need to keep their Tortoises very wet. If a company like Mega-ray are happy
to use this kind of rubbish to help sell lamps, then this humidity thing will go on & on.

This is what I first said the first time I heard about this
Subject: humid hides



In fact I had Dotty 29 years before I even knew what this pyramiding thing was.

She does have the Odd Bump.

On the subject of calcium some people may find this of interest http://www.provet.co.uk/health/diseases ... ptiles.htm

Matt,

I have no idea why anyone would cite that paper either for (or against) anything. It is one of the worst pieces of "research" I have ever seen published on tortoises. That said, plenty of people have accepted it without question:

For example, writing in “Biology of Turtles” (CRC Press, 2008), Pritchard states “current belief is that the condition derives from excessively dry conditions” and that “when hatchlings are raised on a substrate of wet sphagnum, shells will develop normally” (Biology of Turtles, pp. 70).

I love it. Wet sphagnum! Here?

We have just had the wettest winter for many years. It even rained a bit this morning, so, I popped out a couple of hours ago, right after my last post, to some tortoise habitat just to show you all what the ACTUAL relative humidity is, even among the vegetation used by Testudo graeca:



There you go.

I also have recorders running right down in the roots. The tortoises, including juveniles, are out and active. Basking and feeding. You can see that the air temperature is just below 21C. However, the shell temperature of the tortoises was as high as 37 C. Their core temperatures are in the 28-32 C range.

As a generalisation, the RH among the plant roots just below the surface where juveniles hide, tends to be around the 60% level.

This is the type of microclimate we're talking about (photographed a couple of weeks ago):



I have a lot of very reliable data on this. I can say with total confidence that the assertion made in that paper that "“many species of tortoises live most of their lives hidden either in caves (e.g. Testudo horsfieldii, Gopherus sp.) or on the ground surrounded by high humidity even during arid conditions” and that "areas with a humidity of nearly 100% for hiding should be provided to the tortoises at all times” is simply wrong. These environments are not present in nature. There is an excellent, really well done study on Gopherus burrows. In the most detailed and comprehensive study yet carried out on Desert tortoise burrows in Nevada, Bulova (2002) established accurate environmental data for more than 70 individual burrows over an extended period and recorded burrow relative humidity levels ranging from 6.1 to 44.5%, compared to surface relative humidity levels of 4.1 to 32.2%.

Not one approached 100%. Over 15+ years I have carefully measured such microclimates all over the Mediterranean - and my finding are very consistent. The claim in that paper that there are areas of "high humidity" (with the inference this is around 100%) available to tortoises "even during arid conditions" is totally false.

Don't even get me started on the "cellular dehydration" rubbish!!!

Andy

Now thats a view Matt.

Thanks Andy, really helped having it broken down into smaller sections.

Gordi

Thanks Andy.
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Gordi,

Yes great views, if only we could have Andy's spring weather in our Summer, me & the tort would be a lot happier.

I hear that !!! I have always loved the winter.. since having the torts about I have to say thats changed somewhat. I heard on Radio 4 the other day that spring is now 12 days earlier than it used to be . I guess just not this year

Gordi

Even I understood

Andy, apart from calcium intake, d3 metabolism and protein intake...do you think there are evironmental factors involved?

You have mention in your books that microclimates play a role but I don't fully understand in which way. Maybe general water balance instead of the 'cellular dehydration theory'?

I don't believe you have to expose arid tortoises to 100% humid microclimates, I also think it is crazy but too many keepers have experienced better results with higher humidity than in the past, when people used to take into account just macroclimatic conditions when desingning enclosures (no microclimates at all or microclimates much less than 60%). I guess you can't separate environment and diet when dealing with cold blooded animals but believe me: I still find it the hardest thing for me to undestand of this hobby... in captivity.

My own graeca hatchlings are housed indoors this year (I have just moved). They sleep in buried terracota caves with completely dry bottom substrate and around 70% air humidity inside (I slightly spray the sand on top of the caves every day) and they seem to develop nicely. Thay have a weed based diet, UV exposure, calcium and mineral supplementation, open topped enclusures and temp gradients of 32-20 during the day. Around 16ºC at night.

Last question: when are you going to publish your last research on this topic? I can't wait