With proper nutrition and care, a desert tortoise can live more than 100 years. The wrong diet, on the other hand, can significantly shorten his life span, even though it may take years for symptoms of a poor diet to appear. A healthy diet for a pet tortoise is much the same as for a tortoise in the wild, but with a few additions to ensure all his nutritional needs are met.
Grasses should make up the bulk of a desert tortoise's diet, composing around 85 percent of his total daily food intake. Ideally, the grass will be growing within the tortoise's enclosure so he can graze throughout the day. Plant bermuda grass or clover, or native grasses such as curly mesquite, vine mesquite, deer, blue grama, bamboo muhly or Arizona cottontop grass. The grassy area should be at least 6 feet square to meet a single turtle's daily grazing needs. If you're unable to grow grass for your tortoise, you can offer him cut grass, like bermuda hay, mixed with about 50 percent tortoise-safe leafy greens, such as collards, dandelion greens, endive, grape leaves, mustard greens, turnip greens and watercress.
The remaining 15 percent of a captive tortoise's regular diet should be fresh vegetables. Be sure the ones you serve are suitable, though; some vegetables can cause long-term health problems, such as gout or impaired thyroid function. Safe vegetables include string beans, snow peas, bok choy, barley, acorn squash, carrots, bell peppers, pumpkin, turnips, lentils, butternut squash and potatoes. Chop the vegetables into bite-size pieces and offer them on a shallow plate or bowl so your tortoise doesn't consume sand along with the vegetables.
Your tortoise needs plenty of calcium to keep his shell healthy and strong. Much of his calcium comes from dark leafy greens, but it may be helpful to add a powdered supplement to his diet. Seek a vet's input before you add any supplement, though. Choose a supplement designed for reptiles and follow the manufacturer's dosage instructions. Sprinkle the powder on moist leafy greens. You can also place cuttlefish or antler or bone pieces in his enclosure for him to chew. A powdered reptile vitamin supplement can also be added to his leafy greens to ensure he is receiving everything he needs.
Some of your tortoise's favorite foods, like sweet fruit, are suitable as rare treats but should not be a part of his daily diet. Treats that are healthy in moderation include apples, bananas, grapes, peaches, plums, tomatoes, apricots, figs, mangoes, oranges and pears.
Foods to Avoid
Some common foods that are harmful to your tortoise are cabbage, mushrooms, celery, cucumber and chinaberry fruit. In addition, some foods have so little value to a tortoise that they should probably be avoided, including corn, bean sprouts, lettuce, radishes, zucchini, broccoli and cauliflower. Food like spinach, kale and parsley should be fed only on occasion, since they can cause bone and organ problems if consumed regularly.