Guidelines on Food or Fluid Restriction [1]

Background
Animal Welfare regulations [2] and the Guide for the Care and Use of Laboratory Animals[3] mandate that all animals be provided food that is uncontaminated, wholesome, palatable, and of sufficient quantity and nutritive value to maintain the normal condition and weight of the animal. The diet must be appropriate for the individual animal's age and condition. Potable, uncontaminated water must be provided in sufficient quantity continuously or as often as necessary to ensure health and wellbeing. Specific nutrient requirements for different animal species are published by the National Academy of Sciences and are referenced in the Guide [4].

Dogs and Cats
Dogs and cats must be fed at least once each day, except otherwise as might be required to provide veterinary care. If potable water is not continually available to dogs and cats, it must be offered to dogs and cats as often as necessary to ensure their wellbeing, but not less than twice a day for at least 1 hour each time, unless restricted by the attending veterinarian.

Guinea pigs and Hamsters
Guinea pigs and hamsters shall be fed each day except as otherwise might be required to provide adequate veterinary care. Food compromising the basic diet shall be at least equivalent in quality and content to pelleted rations produced commercially and commonly available from feed suppliers. The basic diet of guinea pigs or hamsters may be supplemented with good quality fruit or vegetables consistent with their individual dietary requirements. Unless food supplements consumed by guinea pigs or hamster supply them with normal water requirements, potable water shall be provided daily except as might otherwise be required to provide adequate veterinary care.

Rabbits
Rabbits shall be fed at least once each day except as otherwise might be required to provide adequate veterinary care. Sufficient potable water shall be provided daily except as might be required to provide adequate veterinary care.

Nonhuman Primates
Nonhuman primates must be fed at least once each day except as otherwise might be required to provide adequate veterinary care. Infant and juvenile nonhuman primates must be fed as often as necessary in accordance with generally accepted professional and husbandry practices and nutritional standards, based upon the animal's age and condition. Potable water must be provided in sufficient quantity to every nonhuman primate housed in the facility. If potable water is not continually available to the nonhuman primates, it must be offered to them as often as necessary to ensure their health and wellbeing but no less than twice daily for at least 1 hour each time, unless otherwise required by the attending veterinarian, or as required by the research proposal approved by the Animal Care and Use Committee at research facilities.

Other Warmblooded Animals
Animals shall be fed at least once a day except as dictated by hibernation, veterinary treatment, normal fasts, or other professionally accepted practices. If potable water is not accessible to the animals at all times, it must be provided as often as necessary for the health and comfort of the animal.

Food or water restriction refers to provision of food or water at less than the daily requirements of that species or at less than the required frequencies or duration.

General Principles
Restriction for research purposes needs to be scientifically justified and a program established to monitor each animal's weight, behavior and general state of health. Food or fluid restriction often is used in behavioral procedures where food or fluid is to be used to maintain a trained pattern of behavior.

If a target body weight or percentage of free-feeding weight is a component of a food restriction regimen, the manner (including period of time) by which free-feeding weight is established and the manner in which weight reduction will be achieved should be described.

The protocol should describe the frequency with which the animal will be weighed. It should describe the plan for recording amounts of food to be fed for food restriction. It should describe the plan for recording the amounts of water consumed and the intervals at which water is provided. For nonhuman primates, it should describe restrictions on food treats, if any, in the context of laboratory program of enhancement of psychological wellbeing of such animals.

Criteria should be established for providing supplemental food or fluid. The conditions under which animals would be returned to free or increased access to food or fluid in the course of the study should be stated (e.g., illness or during periods in which behavioral testing was not occurring). Conditions in which new free-feeding weights would be established for the animals that serve in behavioral studies should be clearly stated.

Familiarity with the needs of the species is essential to planning an appropriate food or fluid restriction protocol. Consult published data for each species. At least the minimum quantities of food and fluid should be available to provide for normal development of young animals and maintain long-term wellbeing of all animals[5]. When one commodity is restricted, it is common to provide unlimited access to the other. Use balanced laboratory animal diets. If food is restricted, consider supplementation with vitamins.

Veterinary consultation is required in developing these protocols. Consultation with someone who is experienced in using food or fluid restriction procedures with the species in question also can be useful if you do not have the experience. See also chapter 4 in Methods and Welfare Considerations in Behavioral Research with Animals (NIH, 2002; http://www.nimh.nih.gov/research/animals.cfm), which also is available through the IACUC Office as a resource in planning food or fluid restriction protocols.

References:

1. Approved by the Animal Care and Use Committee: November 21, 2002
2. 9 CFR Subchapter A Part 3 Standards.
3. Guide for the Care and Use of Laboratory Animals. NRC. National Academy Press, 1966. p38-41
4. Guide for the Care and Use of Laboratory Animals. NRC. National Academy Press, 1966. p 94-95.
   
5. Guide for the Care and Use of Laboratory Animals. NRC. National Academy Press, 1966. p12.