What to feed your tortoise is not a subject which is easy to generalise as there are many variables!
Getting the diet correct needs an understanding of the individual’s nutritional requirements. This includes knowledge of how the environment affects nutritional requirements, as well as a basic understanding of food chemistry, vitamins and minerals. This can be very complicated.
These are not dietary “preferences”- they are dietary essentials.
We cannot stress this enough: learn about the real needs of the species you keep and try to understand why it has them, and then try to find out how best you can meet those specific needs at home.
In the wild, tortoises tend to be browsers. They can wander over a wide area and in the process take small quantities of any seasonally available food. Some species are known to consume up to 200 different kinds of plants during the year. However, the exact combination of plants, and their status, young, fresh and succulent or old and dry, varies based on each season.
A tortoise’s diet can change throughout the year. This ranges from a fairly high moisture and protein content in Spring, to a very dry, lower protein diet later on in Autumn and Winter.
It can be difficult for them to find enough food, and they may need to walk all day, foraging for food as they go.
By wandering over a wide area, and by consuming such a variety of foods, tortoises should have a well-balanced diet with all the essential mineral trace elements that they require for reproduction and healthy bone development.
Even the best captive diets tend to be very restricted when compared to these natural feeding patterns.
One of the most common mistakes to only feed them their favourite food!
Commercial tortoise diets
You may find a number of ‘complete tortoise diets’ available for sale in pet stores which come in ‘cups’, ‘soft pellets’ and ‘dry pellet’ forms. These are advertised as complete, or almost complete, solutions to all of your tortoise nutrition concerns.
In comparison to the wild diet these diets are generally too high in protein, may have high sugar levels and have inadequate amounts of fibre. However, they can still be a useful source of vitamins and minerals.
We do not recommend that you feed your tortoise only on these products but as an addition alongside normal hay, grass and vegetables.
If you would like to feed these products, please book a consultation with one of our vets, and they will give you advice on the proportions to feed to balance your tortoise’s diet.
Feeding Grassland Tortoises
This would include the Mediterranean tortoises (Testudo species), Desert tortoises (Gopherus agassizii), the Russian tortoise (Testudo horsfieldii), Indian Star (Geochelone elegans), large savannah species such as Geochelone sulcata (African spurred tortoise), Geochelone pardalis (Leopard tortoise) and the Aldabra (Aldabrachelys gigantea).
All of the above tortoises are herbivores. Wild tortoises do not eat meat, other than on a very rare and opportunistic basis. It is not a regular part of their diet. Fruit is rarely found on a grassland too!
Whilst kept in captivity their diet should be high in fibre, low in protein and calcium rich to ensure good digestive tract function and smooth shell growth.
To provide them with the high fibre they need we recommend a diet based on a mix of hay and grasses.
This would include Timothy hay, natural grass and home grown lawn grass. General ‘meadow hay’ and ‘orchard hay’ mixes are also suitable.
It is best to avoid the use of excessively ‘prickly’ seed heads as they can injure mouths and eyes. To prevent this problem we recommend ‘Timothy Gold’ hay which is ‘second cut’ and tends to have less spiny heads than first cut. There is also a salad mix available of short hay pieces, which is ideal.
Ideally this hay based primary diet should be supplemented with grasses and flowers as frequently as possible. You can grow your own grasses, clover, hibiscus and dandelions on a balcony or roof. De-spined Opuntia (cactus) pads are sometimes available from the reptile shops and can also be offered.
Healthy greens. These can also be offered in smaller quantities. This includes healthy greens such as Plantain, Chinese lettuce, Indian lettuce, romaine lettuce, escarole, carrot tops, coriander and parsley. Do not use head lettuces such as iceberg, as these contain very little in the way of vitamins, fibre or minerals.
Commercial ‘Grassland Tortoise’. This food can be soaked and added to vegetable mixes.
Restricted greens and vegetables. Bok choi, choi sum, spinach, broccoli and other greens may be offered but only in small quantities once to twice per week. When consumed in excess they can inhibit your tortoises’ calcium absorption and can cause further health problems.
Calcium and Vitamin/Mineral Supplementation
Tortoises require a lot of calcium in their diets, especially when they’re growing fast or laying eggs. Tortoises may seek out extra calcium to meet these needs and if it is not available, they can rapidly suffer from calcium deficiencies.
Tortoises tend to be found in regions where the soils are rich in calcium and other essential trace elements. Wild grasses have a higher calcium level compared to the supermarket vegetables we buy.
In the wild, they also have free access to sunlight for basking. Natural sunlight contains UV-B radiation which changes vitamin D into its active form vitamin D3. Vitamin D3 helps the body absorb calcium from the food, so if there is not enough, the calcium will not be absorbed and the development of their bones and shells will become restricted.
We prefer that the D3 is supplied by natural methods, i.e. by UVB light, but as UVB light bulbs are unreliable (unless the output is monitored) we recommend the use of a good quality phosphorus free Calcium and vitamin D3 supplement. This will vary from once a week to once a day depending on the diet, lighting and the age of the animal.
Some pure calcium should be added to the food every day and a vitamin/mineral supplement should be added once per week.
The use of a cuttlefish bone or calcium block left in the enclosures allows tortoises to regulate the amount of calcium in the diet. Don’t be alarmed if they don’t use it, some tortoises like this very much, while others will refuse to go near it at all.
What to avoid
Fruit should be given very sparingly or not at all as it can lead to diarrhoea, intestinal parasite proliferation, and colic problems.
We would recommend avoiding a diet based upon ‘supermarket salad’. These not offer adequate fibre or nutrients, and tend to be poor in essential trace elements. Some greens are great to chop and mix in with hay to encourage your tortoises appetite.
High protein foods such as peas or beans should be avoided. ‘Grassland’ tortoises that have been fed on cat or dog food, or other high protein food items frequently die from renal failure or from impacted bladder stones. Peas and beans are also very high in phytic acid, which also inhibits calcium uptake.
Root vegetables are far too high in carbohydrates so should be avoided.
We would always recommend allowing your grassland tortoises to forage and graze naturally. This helps the tortoise to maintain good digestive-tract health and reduces the production of bladder stones. It also keeps them strong and slim, and makes them happy!
If you have any questions about the suitability of your current diet for your pet tortoise and what supplementation is needed, please contact us to schedule a consultation with one of our trained specialist vets.