Nutrition‎ > ‎

Nutritional Guidelines- Vitamin Doses, Etc.

Doses and guidelines
The following information is designed to help you create a better, more balanced diet for your tortoise. Sources and formulas are given at the bottom.

 Weight1         Length1 Calories2 Fat3 Protein3 Carbs3 Calcium4 Vit. A5 Vit. D5,6 Vit. E5
 grams/ounces cm/inches Daily needs- active grams grams grams milligrams,
min-max
 IU's,
min-max
 IU's,
min-max
 IU's,
min-max
 50gr/2oz 6.4cm/2.5in 6 caloriesh- 0.3
o-1.5 
h- 1.2
o-1.5  
h- 4.5
o-3 
11-19 mg2.5 - 5 IU0.25 - 0.5 IU0.025 - 0.05 IU
 100gr/4oz 8cm/3.25in 12 calories    h- 0.6
o- 3 
h- 2.5
o- 3
h- 9
o- 6
21-36 mg 5 - 10 IU 0.5 - 1 IU 0.05 - 0.1 IU 
 250gr/8oz 11cm/4.25in 20 caloriesh- 1
o- 5
h- 4
o- 5 
h- 15
o- 10
36-60 mg 12.5 - 25 IU 1.25 - 2.5 IU 0.125 - 0.25 IU 
 500gr/1lb 14cm/5.5in 32 calories    h- 1.5
o- 8 
h- 6.5
o- 8 
h- 24
o- 16
57-96 mg 25 - 50 IU 2.5 - 5 IU 0.25 - 0.5 IU 
 750gr/1.5lb 16cm/6.25in 48 caloriesh- 2.5
o- 12
h- 9.5
o- 12
h- 36
o- 24 
87-144 mg 37.5 - 75 IU 3.75 - 7.5 IU 0.375 - 0.75 IU 
 1kg/2lb 17.5cm/7in 64 caloriesh- 3
o- 16
h- 13
o- 16
h- 48
o- 32 
115-192 mg 50 - 100 IU 5 - 10 IU 0.5 - 1 IU 
 2.5kg/5lb 23.5cm/9.25in 107 caloriesh- 5.5
o- 27
h- 21.5
o- 27 
h- 82
o- 54 
193-321 mg 125 - 250 IU 12.5 - 25 IU 1.25 - 2.5 IU 
 5kg/11lb 30cm/11.75in 214 caloriesh- 10
o- 54
h- 43
o- 54
h- 162
o- 108
385-642 mg 250 - 500 IU 25 - 50 IU 2.5 - 5 IU 
 7.5kg.16.5lb 34cm/13.5in 290 caloriesh- 14.5
o- 73
h- 60
o- 73
h- 215
o- 146
522-870 mg375 - 750 IU37.5 - 75 IU3.75 - 7.5 IU
 10kg/22lb 37.5cm/14.75in 360 caloriesh- 18
o- 90
h- 72
o- 90
h- 270
o- 180
648-1080 mg 500 - 1000 IU 50 - 100 IU 5 - 10 IU 
 50kg/110lb 64cm/25in 1200 caloriesh- 60
o- 300
h- 240
o- 300 
h- 900
o- 600
2160-3600 mg 2500 - 5000 IU 250 - 500 IU 25 - 50 IU 
 100kg/220lb 80.5cm/32in 2275 caloriesh- 120
o- 600
 h- 480
o- 600
 h-1800
o-1200
 4100-6800 mg 5k - 10k 500 - 1000 50 - 100

Formulas and sources

1. Length/Weight:  SCLcm3x0.191=WTgr, or the 'Straight-line Carapace Length' in centimeters, cubed, times 0.191 gives you the predicted weight in grams. If the tortoise is lighter than the predicted weight, it is probably dehydrated. You can learn more about the formula on the 'Healthy Weights' page. (Donoghue)

2. Daily Caloric Need:  WTkg0.75x72=KCalories, or, the weight in kilograms, to the 0.75th power, times 72 gives you the estimated daily calorie needs for an active tortoise. This would be reduced for an inactive or not growing tortoise (recovering, aged, winter time torpor, etc.) or increased for a very active tortoise (mating, nesting). (Mader, p.253)

3. Ratio of Calories from Fats, Proteins, and Carbs:  'H' is for 'herbivorous', and 'O' is for 'omnivorous'. Omnivorous reptiles should get about 50% of their calories from carbs, and 25% each from fats and proteins. Herbivorous reptiles get 75% from carbs, 20% from proteins, and only 5% from fats. (Mader, p. 255)

4. Calcium:  1.3 to 8mg x Kcal (or, for every Calorie of food, there should be 1.3 to 8mg of calcium). Phosphorous should be between 0.5 to 1 times the calcium dose. (Mader, p. 287)

5. Vitamin A, D, and E Ratios: The basic formula is a ratio of A:D:E of 100:10:1 (Davis)

6. Vitamin D dosage: (Source: Mader, p. 1069) Formula for mammals is 10-20IU/kg of body weight a day. Since reptiles have roughly half the mammal's metabolism, using 1/2 of that dosage 5-10IU/kg/day seems to work well. Vitamin D toxicity is rare, and most often seems to occur when over 50 times the recommended dosage is given for weeks at a time. The primary symptom of vitamin D overdose is calcification of the soft tissues. Vitamin D toxicity is not an issue when the D is delivered by UVB lighting.

Note: Numbers and dosages have been rounded. I cannot guarantee that the math or application of the formulas is accurate- just the best I can do.

Resources
  • Davis, Sam, “Husbandry and breeding of the Red-footed tortoise, Geochelone carbonaria, at the National Zoological Park, Washington.” International Zoo Yearbook, 19: 50-53. 1979
  • Donoghue, Susan,1997. "Nutritional status of tortoises using morphometrics to assess body condition". Vivarium Magazine, Volume 8 Number 2
  • Mader, Douglas R., DVM, ed. Reptile Medicine and Surgery. Saunders Elsevier, 2nd Edition 2006. ISBN 072169327X


Edited 8-15-2012

Updated- Mark Adkins (C) 6-8-2012
Comments