Report Animal Concerns

​​Important Updates on Availability of Irradiated Bedding

Facilities Husbandry ULAM

Corn cob bedding product shortage notice icon

Labs currently using Pure-o’Cel bedding and PIs housing rodents in select buildings using Pure-o’Cel or autoclaved corn cob bedding are NOT impacted by this notice.

About the Shortage

Due to increasing national demand for irradiators in the human patient care industry, the U-M’s bedding distributor notified us in early December that we should consider substitutions for ⅛” irradiated corn cob bedding, such as ¼” or combination bedding.

On Thursday, December 16, we were informed that NO additional irradiated corn cob bedding, regardless of size, will be available after the order(s) placed the week of December 20–23.  This means that supplies of irradiated ⅛, ¼, and combination corn cob bedding will be depleted by the second week of January and irradiated bedding will no longer be available for use in rodent cages.

More Information

As ULAM continues to finalize its many contingency plans to address this nationwide shortage, ONE individual from each affected lab should complete this brief questionnaire yellow lock icon no later than 5:00 PM on Tuesday, December 21, indicating whether or not their lab can make the switch to Pure-o’Cel bedding.

Labs unable to make this transition are asked to provide a short rationale for why their animals must remain on autoclaved corn cob bedding.

Completing this questionnaire as expediently as possible will allow ULAM adequate time to make the necessary adjustments to their husbandry operations. While every effort will be made to identify other suitable alternatives, there will be some limits to the availability of autoclaved or untreated corn cob bedding.

Labs who do NOT indicate their preferences via the Pure-o’Cel Bedding Questionnaire yellow lock icon will likely be transitioned to Pure-o’Cel bedding so that we may continue to accommodate the greatest number of labs.

We recognize that the source and treatment of animal bedding is a significant component within the housing environment. No two beddings are identical, and a change may present a significant variable for some studies. We acknowledge that, for many PIs, any transition in bedding may have substantial impacts on study outcomes.

Approximately 40% of U-M labs have been using Pure-o’Cel as their standard bedding for the past three years. During manufacturing, Pure-o’Cel undergoes specific heat processing that does not require it to be further irradiated or autoclaved.

ULAM has performed multiple studies (published via PubMed in September 2020 and January 2021) to compare Pure-o’Cel to corn cob bedding.

These studies have shown the following benefits to using Pure-o’Cel:

  • Improvements in overall cage environment by decreased ammonia levels and decreased frequency of early change, which means fewer cage disruptions
  • Animal welfare benefits, including increased nesting behavior
  • Increased overall breeding performance

Side-by-Side Comparison

All PIs and Lab Staff who have animals housed in impacted buildings will receive a separate follow-up communication with more detailed information and important next steps once ULAM has reviewed all questionnaire responses.

Please know that the entire ULAM team remains committed to ensuring that your animals continue to receive the best possible standards of care.

Your patience and understanding are greatly appreciated as we work to address this difficult challenge as quickly as possible.


Questions or concerns should be directed to the ULAM Husbandry Management Team at

yellow lock icon denoting level-1 U-M login required for access Links marked with a lock icon can only be accessed using valid U-M login credentials.

Last updated: