Purpose
In order to comply with government regulations (PHS and
USDA), the Association for Assessment and Accreditation of Laboratory Animal
Care International (AAALAC), and The Guide for the Care and Use of
Laboratory Animals, the University of Connecticut Health Center's Animal
Care Committee (ACC) has implemented a revised policy concerning cage densities and
weaning activities for mice.
Action
- The ACC allows a housing maximum of 125 grams to be the
total mouse mass to be grouped per standard 67 sq. in. cage. Post weaned
mice are defined as no longer suckling or greater than 21 days old. An
exception to this 125 gram rule is granted for large or obese mice (e.g., NOD)
where two mice are permitted per cage even if the combined weight exceeds 125
grams. the benefits of social housing takes preference over body mass
but such cages must be flagged with the 125 gram exception sticker.
- Monogam Breeding (one male to one female)- The ACC
recommends one male to one female in a permanent breeding arrangement as the
optimal use of the 67 sq. in. cage size available in CLAC. In this
arrangement, cage densities may temporarily exceed the 125 gram combined mouse
mass for large parents/litters such as out-bred strains of mice (e.g., CD-1
mice). However, birthdates must be noted on such cages, the 21 day
weaning time limit must be observed, and such cages must be flagged with teh
125 gram exception sticker if the weight limit is exceeded.
- Bigam Breeding (one male to two females)- The ACC
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. Such cages must
be within the 125 gram maximum mouse mass limit at the time of breeding unit
set-up. Pups less than 9 grams may stay past the 21 day weaning
deadline, but no more than 10 pups from maximum two litters are allowed per
cage at any given time. Cages exceeding the maximum 125 gram total mouse
mass must be flagged with the 125 gram exception sticker.
- 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 125 grams including the males and the
non-pregnant females. Due to pregnancies, the total mouse mass may
temporarily exceed the 125 gram rule; however, females must be separated
prior to parturition even if this means that the post partum estrus
will be missed. Cages exceeding the 125 gram total mouse mass must be
flagged with the 125 gram exception sticker.
- Investigators and research staff should maintain
familiarity with this density policy and CLAC's flagging system. CLAC
staff will flag, with a pink sticker, cages with pregnant females. On
the same sticker, CLAC staff will record the date of birth (DOB) and the date
of weaning (Wean). Once the date of weaning is reached, CLAC staff will
post a "PLEASE WEAN" sticker as a last reminder. After that, CLAC staff
will wean without further notice if a cage is in violation of this cage
density policy.
Effective Dates: February 22, 2007 thru February
21, 2010
This policy has been approved by a majority vote of the Animal Care Committee
Members
Joseph Lorenzo, M.D., Chair, Animal Care Committee
