Plant Nutritional Content

[kttdid]

Hi there,

I am a tortoise owner and my vet recently told me the best way to calculate how much calcium to supplement in a tortoise diet is to first find the calcium and phosphorus content of the plants I am feeding my tortoise. I have tried to look for some database that has information about the nutritional content of plants (calcium, phosphorus, fiber, protein, etc.) but I can't find any. If someone could help me with this, I would sincerely appreciate it.

***just so we're on the same page, by "plants" I mean things like silver inch plant, spider plant, hibiscus, etc., not things like spinach, kale, etc.

Thank you!

Kat

[Nina]

Hi Kat,

Thanks for contacting us, and it's a really good question that you ask! Unfortunately there is no one resource that I know of that gives levels of calcium, phosphorous, and other minerals in a plant. The reason for this is partly because levels of calcium, etc. can vary hugely, depending on the growing conditions of the plant -- if there are high calcium levels in the soil, and calcium in the water table then the plant will have a higher calcium content in it. Some plants, like peas and beans naturally have a higher protein content, but this can be diminished by growing conditions too. You can try googling the Latin name of a plant, and the word 'calcium', and you might find a scientific study of that plant and its chemical components.

If you are supplementing your tortoise's diet with pure calcium carbonate powder then it is very difficult to overdose on calcium, because it is water soluble and excess tends to be excreted. Tortoises in the wild consume far higher levels of calcium than most captive tortoises have. It's true that very large amounts of calcium can in some cases result in reduced absorption of iron and zinc, but you would have to give consistently large doses of calcium for that to happen.

However, if you are giving a calcium supplement that also contains Vitamin D3 (like Nutrobal), then you do have to be careful, because you can overdose on vitamin D3 and the recommended amounts of Nutrobal are very small ('a pinch per kilo of tortoise'). So we would recommend giving a calcium and D3 supplement every other day and pure calcium on the days you aren't giving the supplement. RevitaliseD3 has less D3 in it than Nutrobal and so less likely to overdose.

You do want to have a diet that has the best phosphorous to calcium ratio, and of course this is difficult if you don't know how much phosphorous a particular plant contains. And of course you want to limit plants that contain oxalic acid (which binds with calcium and prevents the tortoise from absorbing it. Here is a good article on calcium supplementation in diets: https://www.tortoisetrust.org/articles/calcium.htm that might answer some of your questions.

I hope that helps, and apologies for not being able to direct you to one source of information on this (I do wish there was one!).

Nina

[kttdid]

Hi Nina

Thank you so much for your thorough response! It si very helpful to know that the calcium, etc. in a plant varies on its environemt and growing conditions. And thank you for explaining and linking to information on calcium supplementation! This is one area I have always struggled with in tortoise care and different vets have given me differnt information on tortoise care, so I'm never sure what to do. But yor response was very helpful.

Thanks again!
Kat

[Nina]

Glad to be of help, Kat, and please don't hesitate to ask any more questions.

Cheers,
Nina