Here is some diet information related to desert tortoises. The following tables contain

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.

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.


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

Food% Protein% Fat% Fiber%CHO% Ca% P% Dry Matter
Threeawn6.31.534.848.70.590.09 
Globemallow20.42.423.242.33.340.31 
Triodia, slim9.72.033.744.41.010.08 
Brome, foxtail8.531.60.280.2335.9
Grama, red7.62.333.048.40.610.1056.9
Muhly, bush7.31.836.948.10.270.09 
Heronbill13.52.821.247.01.950.3316.4
Mean10.52.130.647.01.150.18 
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 carbonate40.040
Calcium gluconate 9.310
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% PCa:P% Dry Matter
Apples1.1 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 greens24.23.414.350.61.310.443.0:19.1
Broccoli32.9 2.8 11.9 54.1 0.94 0.72 1.3:110.9
Cabbage 16.91.910.5 71.4 0.64 0.38 1.7:1 7.6
Cantaloupe 7.8 1.4 6.8 85.1 0.16 0.18 0.9:18.8
Carrots8.41.58.573.10.280.271:111.8
Chard, Swiss 27.03.59.051.70.990.442.3:18.9
Chicory1.7 3.9  22.90.10.042.5:110
Collards32.75.46.151.01.700.563.0:114.7
Corn, sweet 7.0 2.02.9 44.50.0060.22 0.03:1 27.3
Cress, garden24.5 6.710.451.80.760.721.1:110.6
Dandelion greens18.74.911.163.81.300.462.8:114.4
Endive 25.72.911.460.01.170.781.5:16.9
Grapes 4.04.1 2.755.40.050.041.3:118.4
Grape Leaves5.6 11170.360.094:127
Kale34.64.67.552.01.440.542.7:117.3
Lettuce, iceberg 22.0trace11.166.70.440.441:14.5
Lettuce, romaine21.26.111.757.61.120.422.7:16.0
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 63.50.21 0.10 2.1:114.0
Parsley26.86.710.160.41.340.403.4:114.9
Prickly Pear Fruit0.7 2.3160.050.022.5:17
Prickly Pear Pad 1.3 3.69.50.160.01610:113
Peaches4.7 1.0 5.5 77.5 0.07 0.15 0.5:110.9
Spinach 35.3 3.9 6.5 47.1 1.00 0.55 1.8:1 9.3
Squash, Italian 22.91.4  67.10.510.540.9:15.4
Strawberries6.7 4.713.979.90.200.201:110.1
Tomatoes 15.43.19.266.20.180.380.5:16.5
Turnip greens30.93.28.351.62.540.604.2:19.7
Watermelon6.82.58.186.40.090.140.6:17.4

• 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% PCa:P% Dry Matter
Alfalfa meal, pelleted** 20.93.223.241.21.350.304.5:191.9
Alfalfa hay** 17.32.131.440.31.640.266.3:189.7
Bermuda grass/hay 11.62.125.950.00.530.222.4:136.7

* 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.

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