IACUC Guideline XIX
Food or Fluid Restriction Guidelines for Traditional Laboratory Animal Species

Purpose
Definition
Guidelines
Examples

Purpose:

1. Food and/or fluid restriction may be required in order to achieve a variety of research and/or husbandry objectives.
   • a. Conditioned response research protocols require withholding food and/or water in order to train animals to perform a task while providing food or water as a reward for correct behavior.
   • b. Nutrition studies may require altering the levels of specific nutrients.
   • c. Limit feeding is common for some sedentary laboratory species in order to control obesity.
   • d. For many species, food may be withheld for a specified period prior to surgery in order to prevent vomiting and aspiration of food while anesthetized.
2. It has been shown that some methods of food and/or fluid restriction are physiologically and/or psychologically stressful and, if restriction is allowed to exceed acceptable levels, can be physically harmful to an animal.
3. The goal of these guidelines is to insure that:
   • a. Dietary restriction is appropriate for the species and satisfies study objectives.
   • b. Animals subjected to dietary restriction are appropriately monitored.

Definition:

For the purpose of these guidelines, food or fluid restriction will include any deviation from the normal husbandry procedures.

Guidelines:

1. Food and/or fluid restriction that deviates from the normal husbandry procedures should be described in the IACUC Proposal Application.
2. Withholding of food and/or water for a period of greater than 18 hours requires scientific justification and a literature search for alternatives.
3. The investigator is responsible for assuring that specially formulated diets are nutritionally adequate and palatable.
4. The investigator should plan to monitor parameters such as body weight, hydration status, body condition, and food consumption.
5. Endpoints should be specified in advance. Examples of specific endpoints include:
   • a. Failure of growing animals to gain weight.
   • b. Loss of greater than 20% of the body weight of a mature animal.
   • c. Body condition score of 2 - Mouse is underconditioned: (a) segmentation of vertebral column is evident; (b) dorsal pelvic bones are readily palpable.

Examples:

1. Conditioned Response Research Protocols
   • a. The amount of food/fluid used should be the minimum level that will achieve the objective.
   • b. If food/fluid restriction is to be used in an experimental protocol, the method of restriction and scientific justification for its use should be clearly explained in the IACUC Proposal Application submitted for review and approval by the IACUC.
   • c. Restriction must be based on a measurable parameter such as percentage of ad libitum intake, percentage of body weight compared to a control animal (paired; ad libitum intake), or length of time access of food/fluid is allowed per 24 hours.
   • d. Consideration must be given to alternative methods and/or modifications to food and/or fluid restriction.
   • e. In order to make a knowledgeable determination of an appropriate level of food/fluid restriction, it is necessary to know what normal quantities of food or fluid are required for maintenance of the species. Life stage (growth, pregnancy, lactation, geriatric) and state of health must also be taken into consideration in determining maintenance requirements.
   • f. Unless scientifically justified, food and/or water restriction should be introduced incrementally to allow for physiological and psychological adaptation.
2. Nutrition Studies:
   • a. The principal investigator is responsible for assuring the proper formulation and nutritional adequacy of these diets.
   • b. Specific arrangements for feeding and diet storage should be provided in the IACUC Proposal Application and arranged with the Animal Resource Program.
   • c. These rations frequently vary in form and in palatability. The animals should be closely monitored to insure that an adequate diet is consumed.
3. Pre-anesthetic Fasting:
   • a. For non-rodent and non-rabbit species, food may be withheld for up to 18 hours prior to an anesthetic procedure (i.e. overnight fasting). Water should be available during the overnight fast but may be removed in the morning on the day of surgery.
   • b. In most cases, pre-anesthetic fasting is not required for rodents and rabbits. However, specific surgical procedures may require an overnight fast and should be explained in the IACUC Proposal Application.
4. Limit Feeding to Control Obesity:
   • a. The quantity fed should be appropriate for maintaining the weight of mature adult animals.
   • b. As a program of limit feeding is established, more frequent monitoring of animal weights will be required to determine an appropriate volume of feed.
   • c. Once the program is established, less frequent monitoring (monthly) is acceptable.
5. Dietary Restriction for Other Reasons:
   • a. An explanation of the need for dietary restriction should be provided in the IACUC Proposal Application along with a description of the nature of the restriction.
   • b. Consideration must be given to alternative methods and/or modifications to food and/or fluid restriction.

Last Approved by the IACUC on 12/08/2008