Most zoos in the USA use nutritionally complete commercial diets to feed exotic felids, canids, mustelids, and viverrids rather than attempt to prepare diets in-house. In other parts of the world, a whole or partial carcass (eg, of cows or horses) may regularly be fed. Other prey animals, such as rabbit and chicken, are also regularly offered. A supplement containing at a minimum calcium, vitamin A, iodine, taurine, and some B vitamins should be added to the meat diet. Feeding a complete mixed diet greatly reduces incidence of nutritional problems in captive exotic carnivores; however, such a diet regularly causes fecal problems. Most commercial diets are based on horsemeat and its byproducts, but diets based on beef and poultry are also available. Typical lesser ingredients include fish meal, soybean meal, beet pulp, and ground corn, as well as mineral and vitamin supplements.
Exotic feline diets are usually higher than canine diets in fat, protein, and vitamin A. A diet suitable for most cat species contains 45%–50% protein, 30%–35% fat, 3%–4% crude fiber, 1.2%–1.5% calcium, 1%–1.2% phosphorus, and 20,000–40,000 IU of vitamin A/kg diet (dry-matter basis). These diets are primarily based on guidelines from the National Research Council or European Pet Food Industry Federation. Apparently, exotic cats, like domestic cats, are unable to convert carotene to vitamin A, tryptophan to niacin, and linoleic acid to arachidonic acid. They also probably cannot synthesize adequate taurine (a taurine deficiency has been reported in leopards) and would be susceptible to ammonia toxicity if fed an arginine-deficient diet. Therefore, these nutrients should be considered dietary essentials for all felids.
Frozen and canned cat foods usually are more palatable than dry ones to exotic cats. Many zoos prefer to use frozen diets over canned products, because generally they are less expensive and large quantities are easier to feed. The soft, hamburger-like consistency of commercial diets can result in excess calculus deposits and periodontal disease if hard or unprocessed items are not also provided. All cats fed a soft diet should receive bones with some meat intact twice weekly. Horse or beef shank bones are suitable for large cat species; oxtails, rib bones, or whole rodents can be used for smaller cats. Mice, rats, and chicks are frequently included in the diets of smaller cats. Rodents, poultry, fish, and organ and chunk muscle meats can be offered as occasional treat items to administer medication or to stimulate appetite, but generally they are not required as dietary staples for large cats fed commercial diets.
Canids can be fed frozen, canned, or dry canine diets. Although most canids are less particular than cats, frozen and canned foods are generally preferred over dry ones. Bones should be included in the diet when soft foods are fed. Canids can also be fed meat, with the right amount of vitamins and minerals added, varied with small prey animals like rats, mice, rabbits, and chicken. Small amounts of fruits and vegetables can be included in the diets of foxes and coyotes.
Most mustelids and viverrids do well on frozen feline diets or canned cat foods; a meat-based diet supplemented with the right amount of vitamins and minerals is also appropriate. Many species readily accept small amounts of fruits, vegetables, and cooked egg. Mice, fish, and chicks can be offered as occasional treat items and to stimulate appetite and activity. Rib bones can be given twice weekly to promote dental health. Canned foods may be more palatable but are not recommended as a base diet, because ferrets may not be able to eat enough to meet their needs for calories and protein. See table: Diets of Selected Mammals for a diet used successfully for freshwater otter species.
Procyonids can be fed diets similar to those offered to small canids, or an adequate meat diet can be fed. Feeding a good-quality dry dog food along with apple, banana, and carrot is satisfactory for raccoons and helps minimize obesity problems that commonly result when frozen or canned diets are fed. The red or lesser panda has been maintained successfully on commercial high-fiber primate biscuits and bamboo. The herbivorous food habits of the giant panda require large amounts of bamboo supplemented with high-fiber primate biscuits.
Bears can be fed meat supplemented with vitamins and minerals, frozen canine diet, dry dog food, fish, and/or commercial omnivore biscuits. Polar and Kodiak bears do well on a diet of 25% frozen canine diet, 25% fish (eg, smelt), 15% dry dog food, 15% omnivore biscuits, 10% bread, and 10% apples, although they do also well if no omnivore biscuits and bread are fed. Commercial diets formulated especially for polar bears are available. Other bear species can be fed less fish and more omnivore biscuits, bread, and produce. Bananas and green vegetables can be included in the diet of sun, sloth, spectacled, and black bears. Food intake of captive bears varies widely with the season. Intakes generally are maximal during summer and early fall and minimal during winter. It is advisable to feed extra cod oil (0.5–1 L) to polar bears before their hibernation starts.