In its natural environment, the green iguana is almost completely herbivorous
(plant-eating) from the time it hatches. Iguanas are considered Hind-Gut
Fermenters which means the general well being is directed by the lower
intestinal tract. The lower intestinal tract is responsible for vitamin
production, fatty acid production, water reabsorption, etc.... It is essential
then that, even in juvenile iguanas, a crude fiber of 14-16% should be observed
to satisfy this requirement. Older iguanas should receive a greater proportion
of 16-18% in their diets.
Juvenile iguanas should be fed daily. A good diet consists of 1 part animal protein (water-packed tuna, cooked chicken, hard-boiled or scrambled egg, Purina Trout Chow, dog food, reptile protein diet ) added to 3 parts vegetable material (broccoli and its leaves, Swiss chard, spinach, alfalfa sprouts, beet, collard, mustard and turnip greens, carrot tops and thawed, frozen mixed vegetables). Chop all of the ingredients into a size that can be easily handled by the young iguana. Then mix them thoroughly and store the mixture in the refrigerator in an air-tight container. Once or twice a day, offer a small amount of this mixture after it has been liberally sprinkled with an appropriate vitamin-mineral supplement.
Particular attention to calcium supplements is important1 because young, growing iguanas are very prone to calcium deficiencies. Readily available reptile vitamins should be used to supplement all juvenile iguanas. Growing iguanas may also be fed "expanded"(allowed to expand by absorbing water) guinea pig or rabbit pellets if no reptile diets are available, either plain or as a top dressing over vegetables. This is a convenient way to add necessary vitamins and minerals (contained in the pelleted food) to the iguana's diet. Also, the amount of sunlight whether artifical or natural plays an important part in producing Vitamin D3, which is essential for Calcium absorption.
Older iguanas should be fed 2-3 times per week and can be offered the same items as listed above. In addition, live crickets, mealworms and pinky (neonatal) mice can be offered in small numbers, though many experts believe that feeding live food invites exposure to undesirable bacteria and possible transmission of parasites. Plant material, such as dandelions (flowers and leaves), clover, rose petals, and flowers of hibiscus, carnation and nasturtium, should be offered as well. Many health food stores carry dried dandelion and other edible herbs that can be offered to captive iguanas all year round. Fresh fruit (bananas, berries, apples, peaches, pears, plums) can occasionally be included in the diet.
If a captive iguana is to benefit from live insects (crickets, mealworms), careful attention must be paid to how these insects are reared and fed before they are offered as prey. Mealworms, for example, are often reared in wheat midlings and/or wheat bran, which are calcium deficient. Mealworms nourished on such calcium-poor material consequently become calcium-deficient and so, too, will iguanas feeding on them, often resulting in metabolic bone disease.
Ideally, you should rear all insects destined to be fed to your iguana on a poultry laying ration (usually containing 8-12% calcium) for at least 1 week before they are sacrificed. Add slices of sweet potato to the mealworm or insect container to provide necessary moisture. Crickets and mealworms may also be lightly sprayed with an aerosolized vegetable oil and then dusted with a vitamin-mineral supplement just before they are offered to the iguana.
A fairly recent discovery has provided a probable explanation for the premature deaths of young iguanas despite apparently adequate diets. In the wild, young iguanas obtain needed intestinal bacteria and protozoa by eating the feces of adult iguanas. The micro- organisms acquired this way are essential for digestion of plant material. Baby iguanas are not born with these microbes, so young iguanas reared in captivity never acquire them.
All newly acquired, domestically raised (not wild-caught) iguanas should receive fresh feces from a healthy, parasite-free adult iguana (preferably wild-caught). One dose should inoculate the iguana for life. Some veterinary hospitals are prepared to assist new iguana owners with this process.