Tortoises are herbivorous and, like herbivorous lizards (see Nutrition in Lizards), must consume plant material to maintain healthy gut physiology. Microbial fermentation of plant fiber can be a significant source of nutrients for tortoises. Diets of tortoises in the wild often contain >15% protein (dry-matter basis) in plant materials consumed, because natural vegetative materials are usually high in protein in the pre-seed stage, although a part of that protein is indigestible. While small tortoises consuming pelleted diets can use plant fiber effectively, they should be fed more frequently than larger animals. Small and large tortoises can be maintained on appropriately formulated, extruded, pelleted, or coarsely ground tortoise diets.
Larger tortoises, such as Aldabra or Galapagos tortoises, can consume alfalfa hay along with a complete pelleted food formulated for tortoises or exotic herbivores. Hay should be cut short as it is not possible for these tortoises to chew long hay due to mouth shape. A vegetable mix consisting of broccoli, green beans, leafy greens (eg, romaine, green leaf lettuce, endive) kale, and shredded carrots may be fed as a supplement to a formulated tortoise diet. Such mixes contain adequate protein, calcium, and micro-nutrients; only limited vitamin and mineral supplements should be added. Cultivated fruits are typically poorer sources of protein, calcium, and micronutrients; if fed in significant amounts, vitamins and minerals should be added. Some herpetologists offer oyster shell and pea gravel to tortoises because “mining” activity has been seen in free-ranging animals.
Shell deformities in tortoises have been thought to result from rapid growth associated with the consumption of high-protein diets. Humidity and temperature also may influence shell deformation.
Last full review/revision July 2011 by Joeke Nijboer, PhD; Teresa L. Lightfoot, DVM, DABVP (Avian)