The purpose of this document is to underline the reasoning behind nutritional choices for Omnivorous Tortoises.
We classify tropical and forest environments as mainly producing Omnivorous Tortoises. This is the Red-Foot complex (Geochelone carbonaria), Yellow Foots (Chelonoidis denticulatus), Hingeback's (kinixys complex), and the Elongated Tortoises (Indotestudo elongata).
An organism will adjust to their environment and surroundings over thousands of years, and create Species specific digestive systems to adapt to their environment for the species' overall survival. This is why tropical and forest tortoises are omnivorous. Tropical and forest tortoises, such as the ones listed above, have a much higher likelihood of finding carrion and fruits in their natural habitats.
Reptiles produce Oxalates. Vegetables contain the compound Oxalic Acid which metabolizes into Oxalates. Vitamin C can metabolize into Oxalates.
Oxalate compounds bind to minerals, mainly iron and calcium, throughout the urinary tract system. For some animals, they can simply expel this build-up of CaOx or FeOx naturally in their urine. Other individuals end up with health issues, stones forming in the kidney and bladder. Currently, stressful and invasive surgery is the only remedy for these stones.
Other issues also arise. Minerals bind to Oxalates; in healthy situations, this is a way of clearing excess minerals from the body. Mineral in unhealthy situations are pulled from the digestive tract prematurely in order to bond to Oxalates. Therefore, leaving the animal in a mineral depletion.
There has been correlation to supersaturation of water counteracting this absorption of minerals from Oxalates in the digestive system, a way of healthily flushing the animals system of excess oxalates. Dehydration makes your animal more likely to form Oxalate Stones.
It must be noted that in a study published by Creighton University, Omaha, Oxalates only bond to the minerals of the plant matter it comes from. In the study, absorption rates of calcium were recorded for spinach and milk. Milk naturally does not have Oxalates, Spinach does. The calcium in milk was found to have not been effected by the Oxalates found in Spinach.
Goitrogen rich foods are believed to have an effect on thyroid hormone levels, thus disrupting iodine uptake in the thyroid gland. This is thought to be the cause of Goiters, the enlargement of a thyroid gland that can be painful and uncomfortable.
There are many reasons for the thyroid gland to become enlarged. Diffused enlargement occurs when the entirety of a gland is affected, while solitary enlargement only effects part of the gland. Solitary enlargement can be caused by a variety of reasons, cysts and nodes for example. Diffused enlargement usually presents itself because of goiters and thyroiditis (inflammation). Comparatively, the autoimmune thyroiditis is distinguished as a painless swelling of the thyroid that changes shape and size over time.
Goiters are the thick tissue growth of the thyroid that does not change shape or size, and is caused by the glands overstimulation of two certain hormones (TSH and HCG). When studied, the most popular causes of goiters were not from iodine deficiencies or goitrogenic foods. Current clinical and scientific literature pinpoints autoimmune diseases as the main culprit. A goiter due to iodine deficiency is actually rare.
Although it can be an issue, complete exclusion of goitrogenic foods seems extreme. We always air on the side of caution. Be aware of your reptiles for any lumps. Limit the volume of foods that have goitrogens in them. Food which may contain moderate levels of goitrogens can also be beneficial by providing key minerals and vitamins. This is why it can be dangerous to completely cut them out of a diet for a healthy reptile, because variety and well rounded diets are always the best option.
Sugar rich foods can be a problem in some species. Species of reptiles that cannot process the sugar in fruits and even some vegetables (like carrots) can cause diarrhea. Sugar provides an environment, which has been found to aid in the flourishing of parasitic cultures inside of the body.
The big issue with diarrhea really stems to one thing. Diarrhea causes dehydration. The compound fructose (a common type of vegetable sugar) pulls water to the gut to flush the system. Diarrhea also interferes with the absorption of nutrients from food in your animal’s gut. When wondering if your animal can have fruit or not, look at the location that they come from.
Forest reptiles tend to be more omnivorous, with fruit and vegetables and mushrooms easily accessible to them in their environments.
Desert and arid reptiles tend to have strictly flowering leafy plants and dry grasses available.
Calcium to Phosphate ratio (Ca:P)
The Calcium to Phosphate ratio is an important calculation to know and understand because these two compounds bond together in the digestive system. Optimally, you are looking for a Ca:P of 2:1. What this means is that for every two parts Calcium, there is one Phosphate to bond to. When foods are heavy in Phosphate, it pulls out calcium in the body until the Phosphate reaches the 2:1 ratio.
Phosphate rich foods and phosphate rich bodies will lead to a variety of issues long term.
Calcium deficiencies and stones are the largest issue.
Feeding should be done daily. Tortoises are grazers, so while they have an active photoperiod, they will eat anytime throughout the day.
By photoperiod, I should point out the differences between indoor photoperiods (artificial) and natural photoperiods. Indoor enclosures have sudden exposure to heat and light because everything is changed with a switch artificially. While naturally, the sun gradually heats up an area, or an area gradually cools off after the sun recedes. The difference is, outdoors, animals have natural queue’s, which tell them to stop eating and go to bed. The air pressure, air temperature, surface temperature, and light are the main tells. Air composition and wind possibly help too. Indoors, they do not have these queues, which tell them to stop eating.
What happens then is that your animal will continue to eat until lights out. If your enclosures environment is too cold for the species, then the enclosure suddenly drops in temperature and you reptile is left with a belly full of vegetation.
Remember, reptiles are cold blooded; they need outside sources of heat to digest food. If the food sits, the food will build gas and begin to decay in the belly.
Reptiles do not have the same internal mechanisms that we have to throw up. Some have diaphragms, some don’t. Some have epiglottis’ others do not. If the food begins to rot, there is no way for your animal to expel the mass, and therefore must keep it in it’s belly until they are warmed up and can begin the digestive process. In these instances, the digestive tract reactivates after the food begins to rot.
If this happens once on accident, your animal is unlikely to have severe consequences for the undigested food. The bulk of vegetarian food is carbohydrates, which are easily processed. Vegetable proteins are more easily digested than animal based proteins.
Over a prolonged period of time, undigested food will cause harm. For example, Brumation. And it may lead to infections, lethargy, and poisoning.
Know the specifics of your animal’s optimal hot area and optimal cool area, and their need to brumate or not brumate.
Base diet is green vegetables. About 70% of their diet
Shredded or cubed cactus pads
Romaine (in moderation)
Edible and Organic Weeds
**Baby vegetables are a great route. Vegetables lose a lot of minerals and vitamins as they age. Like sprouts, baby vegetables are jam packed with minerals and vitamins, perfect for a growing animal. Not only are they higher in nutrients, oxalates are found in lower concentrations in baby plates when compared to adult plants per volume. Comparatively, fully mature vegetation is extremely fibrous, albeit lacking the potency of vitamins and minerals.
Do Not feed spinach, parsley, chard or broccoli. They contain high amounts of oxalic acid.
Root veggies, shredded, will add variety into their diet. Usually, I feel these out two to three times a week.
Sun burst squash
Grain and seed is a great dry (or soaked) addition. When offering seeds soaked in water, make sure to remove the seeds prior within a day to keep bacteria and mold growth limited. Tortoises, especially tropical tortoises prefer soaked seeds and legumes.
There are a variety of flowers that are non-toxic. You must be aware of the source of your flowers. Food-grade flowers are hard to find. They must be non-fertilized and fully organic. Runoff from contaminated water can leach pesticides into the flowers which is toxic for all species of reptiles. Just know your sources.
Dendrobium Sp. of Orchid
Fruit should only be fed to animals that come from grassland or forest locations were fruit is readily found in their environment.
The concentration of sugar and Vitamin C is directly related to how much of this food your reptile can eat. In higher concentrations of Vitamin C and Sugar, the less often you should feed them out. Remember, even with omnivorous animals, sugar and vitamin C can cause diarrhea in high numbers.
Fruit should be fed moderately. Fruit is a treat. About 20-25% of their diet.
Peaches and Nectarines
Be aware of acid levels in fruit. Fruit which has a high percentage of acid; oranges, lemons and limes should be avoided completely.
Animal Basted Protein
Protein is more readily available in nature for Tropical Tortoises to consume. That in no way means protein is the only source of their diet. Protein should make up about 10-25% of their diet. This flux is largely based on seasons.
Be aware of the temperature levels of their environment when feeding out protein. Animal based protein is more difficult to digest in the body, so we advise keepers to feed out the following during the "summer" months when digestion is at its highest:
Mice and small pinkies, Frozen thawed
Frisky's Turkey Flavored Cat Food
Repashy Meat Pie
Be conscious of the levels of fat (more specifically the poly and unsaturated fats) in the food you are feeding out. We do not advise feeding out chicken hearts and dog food. We do not advise feeding out beef. Their digestive systems are a lot smaller than humans and the fat impacts their system a lot harder.
You may see many keepers feeding out egg, egg shells, or cooked eggs. Raw egg and egg shell will always have the chance of being contaminated with salmonella. Yes, Reptiles can get sick with salmonella, and even get humans sick if contacted. We discourage feeding cooked egg also, because this encourages tortoises to become egg eaters, and causes a higher likelihood for them to consume their own eggs.
Supplementation generally needs to be a Calcium (1.5% per serving) + Vitamin D3 (3,000 IU/KG)
Repashy Grassland Grazers
Zoo Med Repti Calcium with D3
Mazuri tortoise pellets (soaked)
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