Background

Because feeding practices can influence both animal welfare and research outcomes, departures from standard feeding, including food restriction, require careful justification and oversight (McCay, Crowell, & Maynard, 1935; Weindruch & Walford, 1988). Restricted access to food  has the potential to cause distress in laboratory animals, so its use must be clearly justified and refined to minimize the chance of impairing the welfare of the subject. Therefore, the Animal Research Committee (ARC) has established the following policy.

Policy

Animals must be fed a nutritionally complete diet – in most cases, ad libitum – unless adequate scientific justification for the use of food restriction for experimental purposes is provided in the ARC protocol. All protocols involving food restriction must include monitoring procedures that will ensure the animal's welfare, with particular consideration given to potential impact on growing animals. The level of food restriction may be based on animal body weight, weight or amount of diet, or energy content of a diet.

The following points must be addressed in seeking ARC approval for food restriction:

  • The least restriction that will achieve the scientific objective should be used, and refined procedures should be instituted to limit it. For example, restricted access to food is often used in behavioral training studies, but it can be minimized when a highly preferred food reward item is used as positive reinforcement.
  • ARC protocols utilizing food restriction must describe the necessary level of food restriction, potential adverse consequences of restriction, and methods for assessing the health and well-being of the animals.
  • Because of variation in food requirements and nutritive status among individuals of the same species, average guidelines for food intake are not appropriate. Food intake data should therefore be based on age-, sex-, and strain-matched controls.
  • Animals on a restricted diet must be monitored daily for continued good health. Weight must be monitored at least twice per week, unless indicated otherwise in an approved protocol, and records on body weight must be kept. Other parameters (e.g., body condition scoring) for measuring health appropriate to the species should be monitored in consultation with Division of Laboratory Animal Medicine (DLAM) veterinary staff.
  • Restriction intended to produce more than 20% decline in body weight is discouraged and requires strong scientific justification.
  • Written records should be maintained for each animal to document daily food consumption and any behavioral and clinical changes used as criteria for temporary or permanent removal of an animal from a protocol.
  • Investigators utilizing food restriction protocols must communicate with DLAM animal care staff. To prevent animals from receiving improper rations, DLAM staff must be informed about periods of restriction and about rest periods when full or supplemental food can be provided. To communicate to DLAM staff during periods of food restriction, special DLAM treatment cards must be placed on the cage indicating that the investigator’s laboratory will be responsible for feeding animals, and the duration (start and end dates) for this special feeding schedule must be noted on the card. These treatment cards may be obtained from DLAM.
  • Food restriction and weight loss may be required clinically for an individual animal at veterinary discretion, including for management of obesity. If an investigator considers such intervention may be necessary, DLAM veterinary staff must be consulted to establish a new baseline weight before initiating restriction.
  • This policy does not apply to food restriction prior to surgery or anesthesia.

References

  1. McCay, C.M., Crowell, M.F., Maynard, L.A. (1935). The effect of retarded growth upon the length of life and upon ultimate size. J Nutr 10, 63-79.
  2. Weindruch, R. & Walford, R.L. The Retardation of Aging and Disease by Dietary Restriction (Thomas, Springfield, IL, 1988).
  3. Guide for the Care and Use of Laboratory Animals. National Research Council, 2010.
  4. Guidelines for the Care and Use of Mammals in Neuroscience and Behavioral Research. National Research Council, pp. 49-61, 2003.
  5. Interdisciplinary Principles and Guidelines for the Use of Animals in Research, Teaching and Education. The New York Academy of Sciences, pp. 7-8, 1988.

Approved 11/13/00; Revised 1/28/02, 7/26/04, 10/24/06, 7/26/10, 3/9/26; Updated 1/18/11, 7/26/19