Purpose

In order to comply with government regulations (PHS and USDA), the American Association for Accreditation of Laboratory Animal Care (AAALAC), and The Guide for the Care and Use of Laboratory Animals, 8th edition, (NRC, 2011) the UConn Health’s Institutional Animal Care and Use Committee (IACUC) has implemented a  policy concerning cage densities and weaning activities for mice.

Action

1. The IACUC allows a housing maximum of 200 grams to be the total mouse mass to be grouped (no more ethan 5 mice) per cage. Post weaned mice are defined as no longer suckling or greater than 21 days old.

2. Monogam Breeding (one male to one female)- The IACUC recommends one male to one female in a permanent breeding arrangement.  Birthdates must be noted on such cages and the 21 day weaning time limit must be observed.

3. Bigam Breeding (one male to two females)- The IACUC recognizes the necessity for difficult breeders (need for cross fostering and utilizing post partum estrus) to be set up in a bigam breeding arrangement with a permanent presence of the male with two females.

4. Multigam Breeding (one male to more than two females)- Harem breeding is permitted provided the total mouse mass at the time of breeding cage set up is less than 200 grams including the males and the non-pregnant females.

5. Investigators and research staff should maintain familiarity with this density policy and CCM’s flagging system. CCM staff will flag, with a pink sticker, cages with pregnant females. On the same sticker, CCM staff will record the date of birth (DOB) and the date of weaning (Wean). Once the date of weaning is reached, CCM staff will post a “PLEASE WEAN” sticker as a last reminder. After that, CCM staff will wean without further notice if a cage is in violation of this cage density policy.

Effective Dates:  February 27, 2025 through June 30, 2025