Overview of Exotic Cat Nutrition
Cats are obligate carnivores. They derive most of their energy requirements from protein. The natural diet of cats is rich in proteins and therefore cats had no evolutionary need to synthesize as many amino acids as omnivores did. They have an absolute requirement for protein, and cannot synthesize the amino acids taurine, arginine, methionine and cystine. Meat diets will provide these amino acids, however diets that contain more carbohydrates may be deficient.
All-meat diets pose potential problems, however. A calcium:phosphorus ratio imbalance may lead to growth problems or metabolic bone disease. The Ca:P ratio in the body is 2:1. The Ca:P ratio to aim for in the diet is between 1:1 and 2:1. All-meat diets are high in phosphorous and have little-to-no calcium. They also may be lacking in vitamins A, E and D, which are found in adipose or organ tissues.
Vitamins B and K are provided by gut contents of whole prey and would be lacking in an all muscle-meat diet. Organ meats such as liver, kidney and heart tend to have the worst ratios of Ca: P and may run as high as 1:44.
According to the AZA Nutritional Advisory Group (NAG) Tiger and Cheetah Nutrition Food Preparation and Feeding Guides (found at www.nagonline.net): Commercially prepared feline diets or properly supplemented carcass meat should be considered the dietary staple for cheetahs or tigers. These guidelines may also be considered adequate for all non-domestic cats. Composition should closely adhere to the National Research Council’s recommendations for dietary composition parameters for domestic cats. The research conducted in tigers (Dierenfeld 1987; MacDonald et al. 1984; Hackenberger et al. 1987) and reviews of felid nutrition for cheetahs suggests that the domestic cat remains the best model for establishing dietary composition parameters for both cheetahs and tigers. Both recommend the addition of the amino acid taurine to heat processed diets, and keeping the levels of Vitamin A to a maximum of 15,000 IU/kg (dry basis) (approximately 25,000 IU/kg wet weight basis), as some studies have shown some zoo felids to have excesses of vitamin A and deficiencies of taurine. No vitamin supplements should be necessary with properly formulated and stored commercial diets.
Both the cheetah and tiger NAG nutritional guides recommend fasting the animals one to two days a week, and providing shank or other large bones on those days. Feeding femur bones, oxtails, or rawhide has the additional function in promoting periodontal health.
An excellent discussion of nutrition in domestic cats may be found in “The carnivore connection to nutrition in cats” JAVMA 2002;221(11):1559–1567.
In this article the specific nutrient requirements for cats are outlined. Because cats are obligate carnivores they have nutritional and physiologic adaptations that are different from dogs and other omnivores. Unlike omnivores, cats have not developed many of the metabolic pathways for processing higher carbohydrate diets. Due to a reduced activity level of the enzyme hexokinase, there is minimal hepatic glycogen synthetase activity. The net effect of this is poor conversion of glucose to glycogen and the excess glucose not used for energy will be stored as fat. Thus cats fed high carbohydrate, low protein diets may become obese. This applies to big cats if they are fed diets that contain carbohydrates. Commercial dry cat foods usually contain moderate to high levels of carbohydrates and may predispose cats of all sizes to obesity.
If an all muscle-meat or a muscle and organ meat diet is fed, the diet must be supplemented with some form of calcium.
To supplement 1000 g of meat (1 kg or 2.2 lbs):
Cats have increased requirements (relative to omnivores) of water-soluble vitamins. They have requirement for niacin (vitamin B-3) because of a low conversion from its precursor tryptophan. They also have a requirement for Vitamin D. They have requirements for pre-formed vitamin A as cats cannot utilize carotenes, however carotenoids are still important in their diet. Balanced commercial diets should contain all of the necessary vitamins.
What to Feed
There are many opinions as to which diet to feed non-domestic cats. Whole prey would be the most natural diet, however it is usually not the most practical method of feeding. According to USDA Policies for Nutrition for Large Felids, diets must be wholesome, palatable and free from contamination. USDA recommends the use of commercially prepared diets for feeding non-domestic cats, but does not specify any particular brand. Examples of frozen meat diets from four major commercial companies that produce specialty diets for exotic carnivores are; Nebraska (Animal Spectrum Inc.) Premium Feline Diets, Milliken Toronto Zoo Feline and Canine Diets, and Natural Balance Zoo Carnivore Diet. Frozen meat diets are usually the diet of choice at most zoos and larger institutions. Dry diets have been shown to be nutritious, but cats may shun them due to their texture or palatability. Mazuri (Purina) and Eukanuba have proven to be acceptable dry diets for exotic cats.
How Much to Feed
A general rule is to feed adult small and medium sized cats (up to 40 kg body weight) 4 to 8 percent of their body weight daily. Large cats require only 1.5 to 3 percent of their body weight in food daily. Young growing cats may require 10–25% of their body weight in food each day. These amounts will vary based on the fat content of the diet. Some diets have a higher fat content than others and the feed amounts should be adjusted accordingly. It is best to feed captive cats a lean diet (less than 10% fat) allowing them the enrichment of eating more food each day, while preventing them from gaining too much weight. Obesity in non-domestic cats is common and should be avoided. Many institutions fast their cats one night each week. The theory behind this is that wild cats do not necessarily eat every day. Offering the cats bones on fast night is enrichment for them and helps to keep their teeth clean. Weekly fasting may help to keep the cats from becoming obese. Offering whole prey such as rodents, rabbits or poultry, or chunk horsemeat one night per week provides variety and dietary enrichment.
Fresh water should be provided at all times. Containers for water must be sturdy and for the larger cats, bite-proof. Stainless steel buckets hooked to cyclone fencing, or concrete bowls or troughs that are difficult to overturn are ideal. Galvanized buckets for medium and large cats are generally a bad idea as most big cats can easily bite through and destroy a galvanized bucket. This could lead to dental problems or at a minimum require water buckets to be replaced on a frequent basis. Some big cats will even destroy the stainless steel buckets, so other containers must be provided.
Laurie J. Gage, DVM, DACZM
USDA APHIS Animal Care
Basic Medicine and Husbandry of Non-Domestic Cats
Wild West Veterinary Conference 2010