Research and Funding

Aged Rodent Colonies Handbook

Available Strains

Notice: The NIA has long provided biological resources to the research community to facilitate research on the biology of aging. As of January 1, 2014, the NIA will no longer charge users for the biological resources, nor any related shipping fees due to a new interpretation of the regulations that govern contracting. Notice Regarding Pricing.

Inbred Rats: Fischer 344 (F344)
Brown Norway (BN)
Hybrid Rats: F344xBN F1 (F344BN)
Inbred Mice: BALB/cBy
Hybrid Mice: CB6F1 (BALB/cBy x C57BL/6)
Caloric Restricted Mice:

C57BL/6 (males only)

On some documents from the Contractor, you will see suffixes after the strain name. The ‘J’ after the mouse strain names indicates that the foundation stock came from The Jackson Laboratory. If the suffix says JN or JNia, it indicates Jackson stock but bred in the NIA colony. A single N after F344 (F344/N) indicates the F344 foundation stock came from the NIH. Likewise the suffix ‘BiRij’ after BN (BN/BiRij) refers to the foundation stock for the Brown Norway rats. The source of the foundation stock and when the stock was re-derived is provided on the Colony Monitoring and History page.

We strive to have animals available out to at least the 50% survival age, but availability fluctuates due to changes in demand. An idea of the oldest available for each strain is available, but the ages listed on this website are up-dated monthly and are intended only as an approximation. Contact the order desk ( for availability of specific strain/gender/ages.

Notice: change in source of F344 foundation stock

For all previous new F344 colony development, the NIA used foundation stock from the NIH Animal Genetic Resource. This facility was closed around 2004. Unfortunately, the F344 breeding stock from the NIH colony that was sent to the Rat Resource and Research Center would not breed, so this source of F344 stock is lost to us. The last stock we received from the NIH, for the caloric restriction colony, also bred poorly, suggesting an unknown genetic change in the NIH foundation stock. To ensure that we used foundation stock from a source that would likely be available for the long-term and for which the breeding patterns were consistent with F344’s history, we chose the Charles River-derived Fisher rat, F344-cdf. The description of the F344-cdf can be found at

Before making this decision, we had a genetic comparison done between the F344-nih (n = 18) and F344-cdf (n = 12). On a panel of 106 SNPs spanning all chromosomes, 100 of them were identical between the two colonies (94.3% identity):

  • four markers were fixed for a different allele in F344-cdf from that in F344-nih (chr 1 cM 89.1, chr 2 cM 72.8, chr 4 cM 98.9, chr 10 cM 77.2)
  • one marker was fixed in F344-cdf and segregating in F344-nih (chr 12 cM 27.2)
  • one marker failed in all F344-cdf but worked in all F344-nih (chr 15 cM24.5), suggesting a mutation in the primer region or possibly a deletion in the region

While we cannot be sure how the change in the foundation stock will affect aging phenotypes, we feel that this is the best long-term solution to the loss of the NIH foundation stock. We developed colonies of F344-nih (using breeding stock from our caloric restricted colony started in 2004) and F344-cdf in parallel so that investigators can compare the two substrains in their assays. Entries of the F344-nih began in the spring of 2013 and ended in early 2014, so aged F344-nih will only be available until early 2016. Investigators wishing to make such comparisons should plan accordingly. In the beginning, F344-nih will be the default strain shipped unless the order states a specific request; by spring of 2014, F344-cdf will be the default strain for young animals because entries of F344-nih ended. Therefore there will be a period of 1.5 to 2 years (dependent on the ages requested) where young rats will be from F344-cdf background and old rats will be from F344-nih background. This transition period is unavoidable. By early 2016, all F344 will be of the F344-cdf background.

The first cohorts of F344-cdf will be set aside for a lifespan study and the results of that study will be posted here as they become available. If anyone wants to share data comparing F344-cdf to F344-nih, we would be happy to post it here with appropriate citation. To submit comparison data, contact Dr. Nancy Nadon,