Adapted from E. Dierenfield, M. Bush, L. Phillips, R. Montali and other contributors
(from E. Dierenfeld)
Unique nutritional requirements of felids must be recognized in feeding captive tigers, including the need for high protein and fat diets, inclusion of dietary vitamin A (as retinol), arachadonic acid, taurine, and niacin. General reviews of felid nutrition (Scott 1968, MacDonald et al. 1984), a more specific review applying these data to captive tiger management (Dierenfeld 1987), and a summary of digestion studies conducted on captive tigers (Hackenberger et al. 1987) provide evidence that the domestic cat remains the best model for establishing dietary composition parameters (National Research Council 1984) for the tiger.
Bush et al. (1987) point out that exact nutritional requirements for all nutrients are not known specifically for tigers; therefore, requirements are extrapolated from data on domestic felids (NRC 1984). Diets are formulated, prepared, and fed; some meet dietary needs while others do not and result in tigers with nutritionally related medical problems (e.g., chronic disease, nutritional disorders or poor reproductive performance). Fortunately, most nutritional disorders are of only historical significance due to improved nutritional management (Slusher et al. 1965). This does not exclude other possible nutritionally related disorders observed in tigers such as hind-limb ataxia (Seal, pers. comm.).
Adult tigers are fed to maintain body condition, with general maintenance energy requirements = 140 kcal (body mass in kg).75 (Kleiber 1964). Thus a female averaging 123 kg requires 5170 kcal/day, whereas a 160 kg male requires 6300 kcal. Metabolizable energy (ME) requirements can be met by daily feeding 3.1 and 4.1 kg respectively, of commercial diets containing about 2.00 kcal/kg (as fed basis) daily, with a digestibility coefficient of 0.84.
Most management programs have found that tigers' appetites and body conditions improve if they are fasted one to two days a week. Either no food is fed on these days or shank or other large bones are fed. Feeding bones (femur bones, oxtails, rawhide) has an additional function in promoting periodontal health and provides an opportunity to exhibit more natural feeding behaviors, and presumably is enriching to the animals (see Chapter 2, Dental). One fast day per week is recommended, which increases the meal sizes to 3.6 and 4.8 kg for Bengal tiger females and males respectively (Sumatran tigers less; Siberian tigers more).
Diet quantities should be increased 10-20% in animals housed outdoors during winter months, and decreased by the same amount during summer months when appetite drops. Increase diet to ad libitum during lactation.
Commercially prepared feline diets (see box) or properly supplemented carcass meat should be considered the dietary staple for tigers. Composition should closely adhere to nutrient specifications as outlined above. Recent studies with zoo felids have reported excesses of vitamin A and phytoestrogens, and deficiencies of taurine in various commercial preparations. Responsive manufacturers are correcting these potential health problems by reducing retinol to levels of approximately 15,000 IU/kg (dry basis), minimizing the addition of estrogenic plant materials, and increasing the addition of taurine, particularly in heat-processed meat products. No vitamin supplements should be necessary with properly formulated and stored commercial diets.
The advantage of the commercial diets is that they are readily available, require little or no labor in preparation, and are assumed to be formulated with a sound nutritional basis. The disadvantage is that it does not resemble a tiger's natural diet and disallows "hunting" as seen in captive tigers fed whole or partial carcasses. Some managers consider commercial feline diets very boring for the cat and unavailable to Southeast Asian zoos. For example, Indonesian zoos feed their tigers kangaroo meat and Chinese zoos feed mostly chicken. Economics determine the components of these diets as the ingredients vary with the change in cost of producing the diet. Thus, the guaranteed analysis remains the same, but the diet may vary in raw ingredients. The guaranteed analysis label does not guarantee that the ingredients of the diet are actually utilized or available for utilization by the tiger (Bush et al. 1987).
(from M. Bush, L. Phillips, R Montali, and
Food preparation and handling is an area of special concern. If the diet is mixed within the institutions, all ingredients should be scrupulously maintained free of contamination from chemicals, pests or microorganisms. Avoid allowing raw diets to warm to room temperature for long periods of time prior to feeding. The practice promotes the rapid growth of bacterial organisms. Frozen ingredients should be properly thawed to reduce bacterial growth and diets fed as soon as possible after mixing. Commercial diets are thawed under clean conditions, free from external contamination, and fed immediately after thawing. Some institutions actually feed the diet while still frozen allowing tigers to eat as it thaws.
The food is weighed and daily records kept as to how much is offered to each individual tiger and how much is consumed. Determination of ration amounts is a dynamic process to meet changes in metabolic needs, such as in seasonal needs, illness, pregnancy, lactation and growth. Proper body weight to avoid obesity should be maintained by diet alterations. These changes should reflect not only energy but also vitamin and mineral needs. Records of stool consistency assist in determining if the diet is poorly digested or possibly inducing diarrhea indicative of enteric disease. The food should be offered on a non-contaminated surface. In most situations feeding is done on the enclosure floor. Feeding should optimally be off the floor or substrate, but this is not always practical as tigers often destroy bowls.
Chunk Meat Supplements. If diets are mixed within the institution they should be supplemented to provide 1% calcium (dry matter basis), particularly if bones are not consumed. This is equivalent to about 7 g Ca/kg meat; a non-phosphorus containing supplement such as CaCO3 (40% Ca) should be used. For this particular example, 17.5 g of CaCO3 (per kg meat) would be added. If meat is lean and/or well-trimmed, vitamins A and E may need to be supplemented at recommended levels. Do not supplement with vitamin A if liver is consumed in any amount. Vitamin E may be necessary in diets based on meats containing polyunsaturated fats (any non-ruminant), at levels providing 50-150 IU/kg dry matter. One reviewer suggests that meat on the bone or whole carcasses can also be supplemented with a good powdered supplement used in conjunction with cod liver oil, even for females with cubs (D. Richardson).
Lindburg (1988) presented excellent arguments for the augmentation of prey items to animal exhibits to enhance natural behaviors, as well as health effects previously discussed. While zoos cannot recreate a completely natural existence, there are points at which nature's ways can guide management in improving the quality of life for zoo animals. Equating an adequate diet with good nutrition leads to dietary substitutions which ignore non-nutritive requirements. These requirements include substitute activities, oral health in relation to food texture, and the psychological aspects of feeding. While psychological well-being remains an elusive concept regarding "pleasure" in feeding, the difficulties encountered in its measurement do not render it unimportant. Until more refined techniques for assessing the mental state of animals in feeding are developed, we may be guided by the fact that the behaviors commonly associated with feeding in nature lead to the conclusion that much of their pleasure centers around food.
Markowitz (1982) described an elaborate system of behavioral enrichment installed to promote displays of hunting and jumping ability of the tiger. Certainly obesity due to lack of activity in captivity is a major problem for zoo carnivores, including tigers. Both of the above suggestions require commitment in terms of labor and/or capital investment, but may prove valuable.
The primary goal from an animal health perspective is to provide a good diet formulation based on sound nutritional concepts and quality sources of dietary components. Other contributors have pointed out the value of attempting to meet the environmental and behavioral needs of captive tigers. One of the ways to meet these needs is to devise a weekly diet that would provide commercially prepared diets, bones and whole or partial carcasses. Care must be taken that animals euthanized with barbiturates are not fed, as this is the most common type of poisoning in large captive felids. Felids feeding on such carcasses may show varying signs from mild ataxia to general anesthesia that may last for days. The liver from such carcasses are especially high in barbiturate levels and cause more severe signs (Bush et al. 1987). In addition, communication between the source of the diets, the veterinary and nutrition staff, and the keepers will allow monitoring of health status, early evidence of nutritional deficiencies, or potential toxic problems. Only then can dietary inadequacies be assessed.
Bush, M.; Phillips, L.G.; Montali, R.J. Clinical management of captive tigers. In TIGERS OF THE WORLD. R.L. Tilson and U.S. Seal, eds. Noyes Publications: Park Ridge, NJ, Pp. 171-99, 1987.
Dierenfeld, E.S. Nutritional considerations in captive tiger management. In TIGERS OF THE WORLD. R.L. Tilson and U.S. Seal, eds. Noyes Publications: Park Ridge, NJ, Pp. 149-60, 1987.
Hackenberger, M.K.; Atkinson, J.L.; Niemuller, C.; Florkiewicz, R.F. Digestibility and metabolizable energy of diets for captive tigers. In TIGERS OF THE WORLD. R.L. Tilson and U.S. Seal, eds. Noyes Publ.: Park Ridge, NJ, Pp. 161-66, 1987.
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