Diet Supplements for Tortoises
- calcium, vitamins & minerals -
Hatchlings have a high demand for calcium (Burmese Star, G. platynota)
Indian Star (Geochelone elegans) and Burmese Star (Geochelone platynota) tortoises have comparable care and dietary requirements. Read the main diet page first.
Researchers are still trying to determine the ideal amount of protein in tortoise diets. Opinions and recommendations vary.
Now, protein measured on wet basis cannot be directly compared to protein measured in dry substance. For example, the protein content of dandelions is 2.7% on wet basis and 18.7% in dry matter (Star Tortoises, 2007).
Tortoise Trust mentions in one of their online nutrition articles (see links page) that the safe upper protein limit in the diet would seem to be 7%. Wild tortoises typically eat about 2-6% plant protein on WET basis.
Dr. Hartmut Wilke comments in his book (My Turtle, 2009) that the ideal tortoise diet should contain 20% plant protein for adults and 24% for youngsters in DRY substance. Crude fiber content should be 12-30%.
According to Susan Donoghue, MS, DMD, DACVN (in Mader's Reptile Medicine and Surgery, 2006) most herbivorous tortoises consume diets that contain about 75% carbohydrates, 20% protein, and 5% fat. High fat levels, above 12%, can cause digestive upsets in herbivores.
If you feed your tortoises prepared diets aka pellets, check the container labels. Choose products that are high in fiber, low in protein, and low in fat. Ideally, use them as a supplement only to cover any potential nutritional deficiencies.
b.) Calcium to phosphorus ratio
For tortoise diets, the traditional recommendation is that the calcium to phosphorus ratio (Ca:P) should be at least 2:1. A ratio of 5:1, or higher, would be even better. Sprinkle some phosphorus free calcium carbonate powder on foods, especially if you use grocery store greens, to up the calcium content (see calcium info below).
Update 2012: Based on newer studies, the need for calcium in tortoises may be even greater than previously believed. For example, a recent study done on plants eaten by Egyptian tortoises in the wild revealed that the mean Ca:P ratio was about 14:1. The Ca:P ratio ranged from 3.92 to 32.44 (The Batagur #2, TTPG, 2012).
Indian Star tortoise (G. elegans), Sri Lankan type, enjoying her breakfast
Supplementation is a controversial topic in captive tortoise care. Some keepers believe daily supplementation with calcium and multivitamins is very important for growing tortoises. Others feel that over supplementation is a real danger and find supplements totally unnecessary. The rest fall somewhere in between. They use calcium and vitamin supplements, but not daily.
If you are sure your tortoise's diet is spot on, which is very hard to do, he may not need any vitamin supplementation. However, ensuring adequate calcium, mineral, and vitamin intake is important for tortoises, especially for young, rapidly growing ones and egg laying females.
Who's been eating cuttlefish bone...? A Burmese Star!
a.) Reptile calcium supplements
Pet stores sell many different brands of reptile calcium supplements. I have used the phosphorous-free, ultra fine Rep-Cal calcium powder for many years as my main calcium powder supplement.
During the spring, summer, and fall when all my tortoises are outside and synthesize their own vitamin D3 from the UVB of sunlight, I only use plain calcium and/or cuttlebones. For tortoises that stay indoors mid winter, I occasionally rotate calcium powder with vitamin D3 with plain calcium during those months.
Caution! Products containing vitamin D3 should always be used very sparingly, if at all (use good quality UVB bulbs instead), because vitamin D3 can be dangerous if overdosed.
b.) Human calcium supplements
If you choose to use human calcium supplements, select a product that consists of pure calcium carbonate powder with nothing added. If your tortoise spends his days outside in the natural sun, he does not need vitamin D3 supplementation. Just plain calcium.
c.) Cuttlefish bones
I keep cuttlebones (cuttlefish bones, Sepia bones, pic) in my indoor and outdoor tortoise enclosures as a secondary calcium source. Some of my Stars nibble on them, and some don't.
Cuttlebone is the hard, internal shell of a cuttlefish (a mollusc). Cuttlebone is mostly composed of aragonite, a naturally occurring form of calcium carbonate. You can find them in the bird department of your local pet store. Cuttlebones are also packaged as Turtle Bones, but at a higher price.
Cuttlefish bones can have a somewhat fishy smell to them. Some tortoises may not like them. Soaking the cuttlebones for several days or leaving them outside in the sun and rain, or near sprinklers, for a a few weeks helps make them more palatable to many tortoises.
Before feeding, I sometimes peel off the hard backing for little ones. I find that soaking the cuttlebones first for 24 hr makes the removal easier.
d.) Ground limestone
Another popular calcium carbonate supplement is finely ground limestone, aka limestone flour (pic). Just put some flour in a shallow dish and allow your tortoises to snack on it at will.
You can find limestone flour in feed stores. It's sold as a calcium supplement for horses, sheep, and goats. If you buy limestone powder from other sources, check that it's food grade.
Loose limestone powder is very messy, but you can easily make your own calcium blocks with it. I mix a small amount of water with the powder to create a paste. I put the paste into a paper cup, let it dry, and then rip off the paper cup. I place the resulting calcium block on a small lid for feeding (pic).
Caution! If you have asthma, be careful when pouring limestone flour. It is very fine, powdery, lightweight, and becomes airborne easily. You don't want to breath in this stuff.
Vitamin & mineral supplements
a.) Reptile vits & minerals
I have used Rep-Cal's Herptivite for a long time. It is a multivitamin, multimineral, and amino acid powder that has been on the market for many years.
Other popular supplements I have used include Repashy's SuperVeggie dust, Sticky Tongue Farms' Miner-All, and Carolina Pet Supply's TNT.
TNT, aka Total Nutrition for Tortoises, consists of dried, powdered plants chosen for their nutritional value. It's available with or without probiotics.
b.) Fortified foods
I also serve fortified foods like Zoo Med Natural Grassland food and Mazuri Tortoise LS Diet a few times a month as an additional nutrition source. I like to keep the pellet foods to less than 10-25% of the total diet.
If you feed these types of foods (see pellets) frequently, there is no need for additional multivitamin supplementation. Commercial tortoise foods are vitamin and mineral fortified. Do provide additional calcium like cuttlebones though.
Frequency of supplementation
The frequency of my calcium and vitamin supplementation depends on the animal's diet, time of the year, and the stage of the tortoise. During winter, when my tortoises eat more store greens and less backyard weeds, I add calcium and vitamins to their food more often. Also, the younger the tortoise, the more often I supplement.
I rotate between powder supplements and commercial diets; I don't use them together. A little bit of everything to round out the diet.
Calcium supplementation is especially important for babies, youngsters, and egg-laying females. Young Star tortoises, like all tortoise babies, need plenty of calcium for healthy bone development. In gravid tortoises, building egg shells draws a lot of calcium from the mother's reserves. It needs to be replaced in the diet.
For example, Sticky Tongue Farms' recommendation is to use their Miner-All reptile calcium & mineral supplement (see above) every feeding from babies to half-growns, every other feeding from half-growns to subadults, and every third feeding for adults. Food for egg-laying females should be supplemented every other feeding.
A general recommendation from Simon Girling, a UK zoological veterinary surgeon (Pet Owner's Guide to the Tortoise, 2002), is to offer plain calcium daily. Multivitamins and minerals can be given twice a week for youngsters and once a week for adults.
Andy Highfield of Tortoise Trust (Promoting Proper Bone Development, 2003) recommends daily supplementation with phosphorus-free, plain calcium and weekly supplementation with minerals. His recommendation for vitamin D3 varies. If your tortoises spend 3-4 hours outside daily and you live in an area that has wild tortoises, you probably do not need to supplement vitamin D3. Otherwise, provide a small amount of oral vitamin D3 at least 2-3 times a week.
Check the poop
Checking your tortoise’s poop regularly allows you to keep track of his health status. Tortoise feces should be dark in color and firm in texture. If your tortoise's poop is constantly lighter green and loose, he may have internal parasites or be eating an incorrect diet. The higher the coarse fiber content in the food, the more undigested plant pieces can be seen in the waste matter.
If you'd like to see a photo of my Burmese Star's poop, click here. :O) The hay fibers are clearly visible in those sun dried droppings. For info on how to perform analysis on tortoise feces, including gross, smear, and float exams, see the fecal exams page.