Tortoise Diet Information

compiled by Fred Caporaso

Calcium:Phosphorus (Ca:P) ratios

 

As you can see, most supermarket fruits and vegetables have a relatively low Ca:P ratio, a low % dry matter (high water content) and high protein.

Desert tortoises in the wild eat a diet with a high Ca:P (greater than 2:1) and a high % dry matter (often greater than 30% dry matter). They can develop shell and bone problems (metabolic bone disease) from a low Ca:P, and kidney/bladder problems (i.e., bladder stones or uroliths) from a diet high in water content (low % of dry matter) and excessive protein.

 

As promised, here is some diet information related to desert tortoises. The following tables contain (1) a nutritional analysis of major foods of desert tortoises in the wild, (2) a list of calcium supplements, (3) an analysis of foods often eaten by captive tortoises and (4) recommended substitutes.

Please note that values are calculated on a % dry weight basis.

I suggest you allow tortoises to graze in the yard as much as possible. Please read the CTTC Desert Tortoise Care Sheet for plant/seed sources for tortoise forage.

 


Nutritional Analysis of the Major Foods of the Desert Tortoise in Arizona and Utah *

Food % Protein % Fat % Fiber %CHO % Ca % P % Dry Matter
Threeawn 6.3 1.5 34.8 48.7 0.59 0.09  
Globemallow 20.4 2.4 23.2 42.3 3.34 0.31  
Triodia, slim 9.7 2.0 33.7 44.4 1.01 0.08  
Brome, foxtail 8.5 31.6 0.28 0.23 35.9
Grama, red 7.6 2.3 33.0 48.4 0.61 0.10 56.9
Muhly, bush 7.3 1.8 36.9 48.1 0.27 0.09  
Heronbill 13.5 2.8 21.2 47.0 1.95 0.33 16.4
Mean 10.5 2.1 30.6 47.0 1.15 0.18  
overall Ca:P = 6.4:1  

* As reported by Hansen, Johnson, and Van Devender, Herpetologica 32:247, 1976.


Calcium Supplements *

 

Form of Calcium % Ca % P
Calcium borogluconate 8.32 0
Calcium carbonate 40.04 0
Calcium gluconate 9.31 0
Calcium glubionate 23 mg/ml 0
Calcium lactate 18.37 0

* Use calcium (Ca) supplements without phosphorous (P) to increase the calcium to phosphorous ratio (Ca:P) in your tortoise diet. Cuttlebone is calcium carbonate and allows self-regulation.


Nutritional Analysis of Foods Commonly Eaten by Captive Desert Tortoises

 

Food % Protein % Fat % Fiber %CHO % Ca % P Ca:P % Dry Matter
Apples 1.1 3.6 6.4 85.5 0.04 0.06 0.7:1 15.6
Avocados 6.1 47.3 6.9 18.2 0.03 0.12 0.3:1 26.0
Bananas 3.0 0.6 2.5 62.1 0.02 0.07 0.3:1 24.3
Beans, green 19.3 1.8 14.1 71.6 0.57 0.44 1.3:1 9.9
Beet greens 24.2 3.4 14.3 50.6 1.31 0.44 3.0:1 9.1
Broccoli 32.9 2.8 11.9 54.1 0.94 0.72 1.3:1 10.9
Cabbage 16.9 1.9 10.5 71.4 0.64 0.38 1.7:1 7.6
Cantaloupe 7.8 1.4 6.8 85.1 0.16 0.18 0.9:1 8.8
Carrots 8.4 1.5 8.5 73.1 0.28 0.27 1:1 11.8
Chard, Swiss 27.0 3.5 9.0 51.7 0.99 0.44 2.3:1 8.9
Chicory 1.7   3.9   22.9 0.1 0.04 2.5:1 10
Collards 32.7 5.4 6.1 51.0 1.70 0.56 3.0:1 14.7
Corn, sweet 7.0 2.0 2.9 44.5 0.006 0.22 0.03:1 27.3
Cress, garden 24.5 6.7 10.4 51.8 0.76 0.72 1.1:1 10.6
Dandelion greens 18.7 4.9 11.1 63.8 1.30 0.46 2.8:1 14.4
Endive 25.7 2.9 11.4 60.0 1.17 0.78 1.5:1 6.9
Grapes 4.0 4.1 2.7 55.4 0.05 0.04 1.3:1 18.4
Grape Leaves 5.6   11 17 0.36 0.09 4:1 27
Kale 34.6 4.6 7.5 52.0 1.44 0.54 2.7:1 17.3
Lettuce, iceberg 22.0 trace 11.1 66.7 0.44 0.44 1:1 4.5
Lettuce, romaine 21.2 6.1 11.7 57.6 1.12 0.42 2.7:1 6.0
Mustard greens 28.5 4.8 10.5 53.2 1.74 0.48 3.6:1 10.5
Oranges 5.2 1.2 4.3 63.5 0.21 0.10 2.1:1 14.0
Parsley 26.8 6.7 10.1 60.4 1.34 0.40 3.4:1 14.9
Prickly Pear Fruit 0.7   2.3 16 0.05 0.02 2.5:1 7
Prickly Pear Pad 1.3   3.6 9.5 0.16 0.016 10:1 13
Peaches 4.7 1.0 5.5 77.5 0.07 0.15 0.5:1 10.9
Spinach 35.3 3.9 6.5 47.1 1.00 0.55 1.8:1 9.3
Squash, Italian 22.9 1.4   67.1 0.51 0.54 0.9:1 5.4
Strawberries 6.7 4.7 13.9 79.9 0.20 0.20 1:1 10.1
Tomatoes 15.4 3.1 9.2 66.2 0.18 0.38 0.5:1 6.5
Turnip greens 30.9 3.2 8.3 51.6 2.54 0.60 4.2:1 9.7
Watermelon 6.8 2.5 8.1 86.4 0.09 0.14 0.6:1 7.4

• Items highlighted bold can be used if necessary until graze items are growing but should be supplemented with Suggested Substitutes (see below) to increase the Ca:P ratio and lower the water content. Utilize a “salad” style if using greens instead of just one item.
• Broccoli, cabbage and other Brassica family vegetables are not recommended. Neither are fruits except Prickly Pear (Opuntia) fruit which should be seasonal and occasional.

 


Suggested Substitutes *

 

Food % Protein % Fat % Fiber %CHO % Ca % P Ca:P % Dry Matter
Alfalfa meal, pelleted** 20.9 3.2 23.2 41.2 1.35 0.30 4.5:1 91.9
Alfalfa hay** 17.3 2.1 31.4 40.3 1.64 0.26 6.3:1 89.7
Bermuda grass/hay 11.6 2.1 25.9 50.0 0.53 0.22 2.4:1 36.7

 

* We suggest using these as additions sprinkled on foods if you must use any greens from the list above to increase Ca:P ratio and lower the water content.

** Available in many pet shops and feed stores.

 


Originally published in the Tortuga Gazette 25(7): 6-7, July 1989.

Updated June 2012 by Don Williams.