Both CR and AL are individually housed. CR is initiated at 14 weeks of age at 10% restriction, increased to 25% restriction at 15 weeks, and to 40% restriction at 16 weeks where it is maintained throughout the life of the animal. CR/AL rodents are sold only by age in months, i.e. 4 months or 24 months, not by weight or age in weeks. Survival curves, food intake curves and body weights of the NIA strains have been published (Turturro et al. (1999) Growth curves and survival characteristics of the animals used in the biomarkers of aging program. J. Gerontology 54A:B492-B501).
Feeding instructions will be provided with the caloric restricted animals. If you are requesting food, please indicate how long you will maintain the animals so that the contractor can calculate how much food you will need. Food is shipped on the trucks with the animals; shipment by overnight commercial shippers is not allowed unless the recipient is not on one of the Contractor’s truck routes. Food is only provided for CR (and AL control) animals purchased from the NIA caloric restricted colony. The NIA does not provide food for animals purchased from the aging colonies. Documentation for the diet formulations is available from the downloads page.
Feed labels are marked as follows:
NIH41: This is NIH31 formula that has been sterilized, but some of the ingredients are changed to ensure the proper levels after sterilization.
NIH31: When multiples of 10 kg are ordered, the NIH41 irradiated diet is shipped. In smaller quantities or odd quantities, the NIH 31 autoclavable diet is shipped. It is labeled NIH31 and must be autoclaved by the end user if sterilization is desired.
NIH31-Fortified: This diet is always shipped autoclaved, so the bags are labeled NIH41-fortified diet.
Starting in January 2009, animals in the caloric restricted colony will be provided nestlets to provide a minimum environmental enrichment to compensate for the lack of social enrichment that the group housed animals experience.