Reptile & Amphibian Forums

While cuttlefish bone does have a lot of calcium in it, the calcium is not absorbed all that well by chelonians. They will get some benefit from it, but they would have to eat a lot to do so, perhaps more than they would find palatable. It's good to keep some around for them to chew on if they want to, but you should also use another source.

Eggshells are much more efficiently absorbed. They are an excellent source of calcium for all animals. But the thing is, most comercially raised egg-laying chickens are fed hormones which can be a potential health problem for tortoises. The way the hens are kept, even bacteria can be in the eggs. That's why you should get eggs that are from a company that has "cage-free" chickens and doesn't use hormones or antibiotics in their feed. They're good for humans and you can use the shells for your animals. Just dry them out very thoroughly and grind them up very fine and use like you would any calcium supplement.

In your post you mention that....."the calcium is not absorbed all that well by chelonians."
Why not, surely calcium is calcium?
Can you site me a ref to your above ref please.

graham(UK)

Graham, I mostly got that information from some tortoise books that I have. Admittedly, those books are a few years old, so maybe they are outdated, hard to say. But I also found a few sites on the internet that say the same thing regarding cuttlebone and eggshells. There does seem to be some controversy on this subject because many sources say cuttlebone is a good source of calcium. The main problem I see is that none of the sources where I got my information really seem to say WHY the cuttlebone is not that well absorbed. I think I may know why, though.

I see some other people on this board have already given some good information, but I'll try to answer you directly as best I can.

The type of calcium in a substance is important to look at. There are many types of calcium including carbonate, citrate, gluconate, lactate, malate and a few more. They all vary in how easily an animal can actually absorb them into it's bloodstream after it eats them. Citrate is more easily absorbed that some of the others, and carbonate is actually not all that well absorbed. Much of it will be excreted in the urine.

The other factor to consider is what is in a given substance along with the calcium. Even though cuttlefish bone and eggshells are both calcium carbonate, there are no doubt differences in the elements that are in them that affect absorbtion of the calcium. Phosphorus, which is in large amounts in cuttlebone, interferes with the abosorbtion of calcium. I believe that eggshells have much less phosphorus. Vitamin D also aids in the aborbtion of calcium, and I know eggshells have more than cuttlebone does.

I will post one of the sites that mention the cuttlebone and eggshell topic in a minute. It is from Highfield, and he also mentions the drawbacks to feeding eggshells. Unfortunately, he doesn't mention how easy it is to overcome these drawbacks.

Mike

http://www.tortoisetrust.org/articles/calcium.htm

Thank you for the ref/data, however I'm not fully convinced about the neg side of cuttlefish bone.

To date I've raised 3 x 5-6yr old Sulcata's (now at 30kg /- each) on 99% cuttlefish calcium with no vits as supplements.
According to my vet who has xrays of them over a couple of yrs, they are showing good bone structure & formation. Now perhaps I've just been lucky.
I also use the cuttlefish with my Leopards (25 group) & my Russians (25 group).

It would be interesting if a test could be set up, Cuttlefish V Commercially available Ca powders, to see the end results in say 5yrs.
I already have the evidence of 5-6yrs Cuttlefish usage!

Again thanks for the input.

graham(UK)

Is cuttlefish the only calcium source you feed, or could part of your success be due to other sources such as grass?

Yes obviously they can get regular intake via the foods which they consume, but cuttlebone is available to them 24/7 & as such must constitute 99% of the calcium they get.
They always have a fresh dish (12" dia) full for them to eat when they feel the need.

Very very occasionally, mainly during the summer, when they are being fed outdoors do I sprinkle a little Limestone powder over the lawn area/salads feeds.

graham(UK)

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Ed
Tortoise_Keepers-subscribe@yahoogroups.com
Trying to keep the fun in Chelonian care

Here Ed, see what you can make of this info. Base of page has make up of cuttlefish bone.

http://www.animalnetwork.com/birds/library/articleview.asp?Section=&RecordNo=1570

graham(UK)

both cuttle bone and egg shells provide calcium in the same form, calcium carbonate.

What other sources of Calcium are good? How is Rep-Cal?
How much is enough and can you give your tort too much Calcium?

My thoughts exactly, still if T'head can provide a reference for us to view it might change our opinion.

graham(UK)

what t'head says is true about calcium sources if the calcium is in different forms, or if other minerals are present. the presence of phosphorus can interfere with the absorption of calcium. too much calcium can interfere with the absorption of other minerals, as well.

i found this page with an abstract of a study evaluating absorption of different sources of calcium (originally published in J. Anim. Phys. and Anim. Nutr.):

http://tinyurl.com/3xfuw

Griffin, that chart seems to go against almost all of the research I have read about calcium absorbtion in animlas and humans. In almost all of the tests I have read about, they say most calcium sources will be absorbed very, very poorly. Most of the calcium supplements sold for human consumption are absorbed at around the 5-20 percent range at the most, according to a lot of research.

I suppose it is possible that different animals will absorb calcium at different levels, so I wonder where tortoises stand compared to humans or other mammals in their ability to utilize this mineral in their diet.

after reviewing the table and abstract, i would agree with what you have said. it is unfortunate that we do not have access to the entire article without having to purchase a subscription to the journal. however, i believe that if we were able to examine the materials and methods, we would find the reason why the numbers are so high regarding absoprtion. the abstract states the rats were fed a semi-purified diet. i would guess that this was a diet completely devoid of Ca, and the sole source of calcium for the rats was from the tested Ca sources. it is known that Ca absorption is dependent upon the amount of Ca in the diet; more Ca in diet, less percentage of total dietary Ca absorbed. in the real world, and in real diets, it is important to consider the source of supplemental Ca. Ca salts and other Ca compounds that are more soluble tend to be absorbed better. sorry for the confusion.... perhaps i can find a better study to illustrate our point, although i know i will not be able to find one regarding tortoises.

griffin

>we do not have access to the entire article without having to purchase a subscription to the journal...

I do have web-access to this journal; unfortunately, J. Anim. Physiol. Anim. Nutri. is only available since volume 81 (1999).

Should anyone close to a School of Veterinary Medicine be interested in the methods and data in this article, check the Vet-school library's stacks. Full reference: Bao SF, Windisch W, Kirchgessner M. Calcium bioavailability of different organic dietary sources (citrate lactate, acetate, oyster-shell, eggshell, calcium phosphate), Journal of Animal Physiology and Animal Nutrition, 78 (1997), 154-160.

Be sure to let us know!

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Ed
Tortoise_Keepers-subscribe@yahoogroups.com
Trying to keep the fun in Chelonian care

Both eggshell and cuttlebone are composed largely of calcium carbonate (95% vs 85%), so absorption should be similar. Neither was noted as containing phosphorus in the sites I checked.

Good point about antibiotics/hormones. Even range chickens, however, can produce Salmonella-contaminated eggs, so the shells should probably be disinfected, perhaps by boiling or microwaving.