NAG Animal Feeding Guidelines


Nutrition Advisory Group (2002) Feeding Program Guidelines for AZA Institutions.


The Feeding Program Guidelines for AZA Institutions were written by the 2000-2001 Nutrition Advisory Group Steering Committee and reviewed by the entire Nutrition Advisory Group membership. The Guidelines are intended to provide direction for AZA institutions for the development and maintenance of an inclusive, practical feeding program for Captive Wild Animals. The guidelines should also be used by AZA inspectors as a resource for accreditation. Any questions concerning the Feeding Program Guidelines should be directed to the NAG Steering Committee.  Barbara Toddes


For more than 2 millennia humans have kept wild animals in captivity. For most of this time the sole reason for captivity was for human benefit – to marvel at the animal’s uniqueness, to show power or wealth or merely for entertainment. Little was done to learn about the nutritional needs of the animals. Although raptors and elephants have been managed in captivity for more than 2000 years, for example, specific nutritional needs and the most suitable physiological model species for both groups of animals remain largely unknown.

Today there are over 6 billion people inhabiting the earth. Humans as a single species have been highly successful and their longevity has soared in the 20th century. The average life span in the United States alone rose from 50 years in 1900 to 78 years by the turn of the millennium. Recent forecasts predict that by the year 2100 the average life span will exceed 100 years in the United States. Why such longevity in the United States? The reasons include improved health care, improved sanitation and living conditions, and improved nutrition.

Nutritional status plays an integral role in the longevity and propagation of many species. Captive propagation is becoming increasingly important for the survival of many species. We need to learn and do as much as we can to improve our management of these species (both captive and free-ranging). Accredited American Zoo and Aquarium Association (AZA) institutions are dedicated not only to the preservation of wildlife in zoos, but the conservation of wildlife in nature as well. To conserve viable wildlife populations, we must strive to learn their needs, lest we may never be able to provide for these needs in either captive or free-ranging situations.

The AZA Nutrition Advisory Group (NAG) herein proposes a set of Feeding Program Guidelines for AZA Institutions. The goals of these guidelines are to help institutions develop feeding programs that: 1) improve the overall nutrition of animals in captivity, 2) gather information on the nutrient requirements and feeding considerations of animals at different life stages, and 3) provide for the physiological needs and well-being of exotic animals in captivity.


Recommended Feeding Strategy for AZA Institutions

  • Aim to provide a nutritionally balanced diet.
  • Provide a diet that reasonably stimulates natural feeding behaviors.
  • Provide a nutritionally balanced diet that the animal consumes consistently.
  • Provide a diet that meets all of the above criteria, and is practical and economical to feed.

Aim to provide a nutritionally balanced diet. A diet is considered to be “nutritionally balanced” when it provides appropriate levels of known dietary essential nutrients based on current knowledge and information. A nutritionally balanced diet must be provided in a suitable form and correct proportion based on the most appropriate physiological model or models for the species. Nutritional status, natural feeding ecology, gastrointestinal (GI) morphology, nutrients contained in the diet of free-ranging individuals, and foods/feeds available to the institution should be taken into consideration when formulating a balanced diet. The “diet” is all foods offered and/or accessible to an animal, regardless of purpose. Foods used for enrichment, training programs, and/or treats need to be included in calculations when balancing the total diet. A nutritionally balanced diet provides the animal with all the known nutrients it requires without gross excesses or deficiencies.

Provide a diet that reasonably stimulates natural feeding behaviors. A nutritionally complete diet that stimulates natural feeding behaviors encourages the animals to obtain food in a manner similar to that in the wild (e.g., giraffe and gerenuk reach up for food). The diet should, whenever reasonably possible, encourage methods of consumption similar to methods in the wild (e.g., chimpanzees work for food in termite mounds), should be of a form as close to natural as possible (e.g., forage for ruminants, whole food/roughage for carnivores), and should allow a similar amount of time spent on feeding (e.g., giant pandas spend most of their day eating; lions spend a relatively short time).

Provide a nutritionally balanced diet that the animal consumes consistently. Of equal importance to a diet formulated to meet all known nutrient requirements is a diet which is reliably consumed by the animal. If the intended animal(s) does not consume the diet due to poor palatability or inappropriate form and/or presentation, the diet is of no value. Diet intake should periodically be monitored to ensure that the animal(s) are consuming the majority of the diet and not selecting only certain items.

Provide a diet that meets all of the above criteria and is practical and economical to feed. A practical diet is one that can be prepared by the appointed person(s) (commissary and/or animal caretaker) using ingredients that are readily available to the zoo or animal care institution. All institutions have budget guidelines. While meeting the nutritional, behavioral, palatability, and functional needs of each animal, the appropriate diet also will fall within practical budgetary constraints.

Recommended Diet Formulation: Steps for AZA Institutions

  • Background.
  • Diet Evaluation.
  • Diet Implementation.
  • Diet Update.

Diets should be formulated in conjunction with, or under the guidance of, a professional with expertise and experience in managed feeding programs and/or nutrition of the species (or closely related physiological models) for which the diets are intended. Consultation with a trained exotic animal nutritionist can help identify the components of a nutritionally balanced diet.

Step 1. Background. A literature review will help pull together information on a particular species or on an individual animal. For SSP/TAG animals this review should start with the Husbandry Manual Nutrition Chapter (contact the SSP/TAG Nutrition Advisor or consult the Nutrition Advisory Group Website for the most up-to-date nutrition information). When working with an animal for which there is no husbandry manual, the literature review should include information on the nutritional, behavioral, and functional needs of the species in the wild and in captivity. Important information includes: the natural diet (accompanying nutrient content, if available) and feeding habits, GI morphology, normal adult weight of males and females, age of maturity, longevity of the species (in captivity and in the wild), and any special physiological needs the animal might have (egg laying, breeding, growth, gestation, etc.). In addition, it is important to include nutritional requirements for the species (or closely related physiological models) that may be available in the NRC report series on nutrient requirements of animals. Diets from institutions working successfully with the species should be evaluated, as well as the holding institutions historical diets. The NAG web site also may provide information ( Literature should be cited appropriately in a document describing the formulation of the diet.

Step 2. Diet Evaluation. Diets can be evaluated for adequacy by hand calculations or by computer-generated diet analysis to determine the nutrient density and nutritional appropriateness of the diet. Any evaluation should be interpreted by a nutrition professional. If there are no known nutritional requirements available for the species in question, an appropriate domestic animal model can be used (e.g., NRC horse requirements for zebras). Specific Taxonomic Advisory Group (TAG) or Species Survival Plan (SSP) nutrition recommendations should be included when available. Laboratory analysis of dietary ingredients is recommended as a periodic check on published values, or when no published values exist. Evaluation of husbandry as it relates to diet, animal response, condition, and weights are all essential components of the evaluation process.

Step 3. Diet Implementation. Concise diet and feeding instructions should be sent to the animal caretaker. It is crucial that animal care staff provide feedback to the appropriate person or department within the institution regarding animal acceptance of the diet.

Step 4. Diet Update. There are several reasons for diet reformulation. Diets may be reformulated based on feedback of animal caretakers, veterinarians, curators or animal managers or as new information becomes available. The nutritional needs of an animal may change throughout its life. Diets should be adjusted when there is a change in life stage, season, or if the animal’s health status can be aided by a change in diet. The dietary needs of a group may change as the group changes in configuration. It is important that someone accurately and objectively assess each animal’s and the entire group’s acceptance of the diet. Since animal caretakers are usually those most closely observing the animals, this responsibility may be theirs. Periodically, as part of the feeding record, the total quantity of the diet consumed by the animal and/or group as well as diet items avoided or consumed only in part should be evaluated. Caretakers also should inform the appropriate personnel of diet preparation problems or special food preparation requirements for individual animals. Animal weight change and body condition should be monitored and reported. It is important to assess the intake of both the individual and group to ensure that each animal obtains correct amounts of food while managing a group situation.

Recommended Dietary Records for AZA Institutions

Record Information. Ideally, dietary records should consist of transaction information, dietary information from previous institutions (when provided), all institutional diet information (up-dates, changes, etc.), and information from daily animal care staff reports (animal weights, abnormal feeding behaviors, keeper comments, evaluations and questions), as well as all other information pertinent to the nutritional health of the animal. Dietary records should be available for review by animal care staff. Ideally there should be a standardized form for this information. Note that for marine mammals it is important to record the actual food intake for each animal on a daily basis.

Record Use. The nutrition records should be an integral part of the feeding program. The records will help document thought processes regarding diet formulation and presentation that may prevent repeating past mistakes. There is very little nutritional information available for most captive wild animals. For this reason, every bit of information collected is immensely important. Records should include information associated with feed intake (including food preferences), feeding behavior, general appearance (weight, coat, eyes, teeth, etc.), change in status (pregnant, lactation, growth, old age, etc.), change in schedule (fasted for vets, did not eat because animal did not come in, etc.), and animal movement (death, moved house, removed from collection, etc.). These records may be used to track feeding trends, plot appropriate nutrient intake for stage of life, identify variability in nutrient requirements (captive vs. domestic animals), and improve overall management of the captive wild animals in our care.

Recommended Food Use by AZA Institutions

Food Used for Behavioral Enrichment. All food used for behavioral enrichment must be calculated into the animal’s diet. Preparation and presentation of the daily diet should aim to ensure appropriate nutritional content and promote natural feeding behaviors. An animal does not need to be consuming its wild diet in order to exhibit natural feeding behavior. Some foods, such as browse and produce, lend themselves naturally to enrichment. Some commercial diets are more difficult to contend with as enrichment items. Nevertheless, every attempt should be made to feed commercial diets in a manner that promotes natural feeding behavior. The natural feeding times of animals should be considered (e.g., animals that feed in pre-dawn hours may need to be fed in pre-dawn hours to encourage diet consumption and promote natural behaviors).

Nutritionally complete feeds. It is recommended to provide a portion of the nutrients through a pelleted, extruded, canned, etc. feed. These products oftentimes are referred to as “nutritionally complete” as they have been formulated by the manufacturer to be nutritionally complete for a particular species. The products are designed to provide all of the required nutrients to the target species and the addition of other foods/feeds can either dilute or complement these products. Some nutritionally complete feeds can be complemented with other foods to provide a diet that is both nutritionally balanced and allows ample opportunity for normal feeding behaviors. Alternatively, the use of additional foods in conjunction with other nutritionally complete feeds may dilute the nutrients provided, producing a nutrient deficient diet. It also increases the likelihood that animals will sort through the items in their diet, selecting items other than those that provide adequate nutrients. The use of supplements in conjunction with nutritionally complete feeds may potentially produce a diet with excessive nutrients that may pose harm to the animal. Use of a nutritionally complete feed (either commercial or homemade) will help to ensure the animal is consistently being offered a similar level and quality of nutrients. Commercial nutritionally complete feeds have the added benefit of allowing dietary consistency across AZA institutions when animals are moved between institutions. Laboratory analyses of nutritionally complete feeds may be advisable as a quality control check and to provide information to the diet formulation database.

Public feeding. The Nutrition Advisory Group does not recommend a public feeding program. Public feeding, if allowed, should be supervised and fed items quantified as part of the diet for all animals.

Food use records. To improve diets and for animal survival, well being, and propagation, knowledge of feeding and nutrient consumption is essential. Knowledge of the nutrient content of any feed or diet is incomplete without understanding the utilization/digestion/metabolism of these feeds/diets by the target species or group of animals. Food can be considered the vector for the needed chemicals (nutrients). It is important to know the nutrients, not just the food, consumed. Nutrient bioavailability, secondary plant compounds, species physiological differences, etc. will all affect how an animal utilizes the nutrients in the food consumed. This is important because the target nutrient levels in the diets fed are often times based on interpolation and extrapolation of data from related species and on feeding experience with the species in captivity.


Food use and animal diets vary greatly among institutions. Through the cooperative efforts of the Nutrition Advisory Group, other SAGs, SSPs, TAGs, and zoo veterinarians and managers, information on the appropriate nutritional husbandry for various species is increasing. The nutritional needs of the animal must be the primary consideration when a diet is formulated. Food used to meet the nutritional needs of captive wild animals can and should be offered to the animal in a manner that promotes natural feeding behaviors. Appropriate diets for captive animals can only be achieved through the cooperation and understanding of all scientific disciplines relating to animal care. Every AZA institution would benefit from personnel whose primary responsibility is formulating nutritionally appropriate diets for the animals.

Copyright © 2002 Nutrition Advisory Group

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