An Alternative to Overnight Withholding of Food from Rats

Withholding of food overnight has been used for numerous experimental purposes, including to reduce errors of intraperitoneal injections by diminishing the size and weight of the gastrointestinal tract, to prepare for gavage or surgery, or to avoid the effects food in the gastrointestinal tract might exert on drugs or nutrients. However, withholding food overnight causes undesirable side effects including loss of body and hepatic weight and decreases in blood glucose concentrations. Withholding food from rats housed on bedding can also lead to ingestion of bedding. Providing rats with commercially available sucrose cubes overnight ameliorated these undesirable effects while still reducing the size of the gastrointestinal tract. Rats housed in cages without access to bedding had an additional reduction in weight of the gastrointestinal tract. Analysis of our results indicated that providing sucrose cubes overnight and reducing access to bedding was an effective alternative to overnight withholding of all food.