Age (wk) Data recorded 3-16 wks body weight
• Top loading balance: Ohaus Navigator, Model N12120 with internal calibration (Ohaus Corp., Pine Brook, NJ).
• Long forceps: for picking up mice by their tail.
- Lily tub: 64-oz paper bucket (Sweetheart Cup Company, Owings Mills, MD)
- Lily tub
- Absorbent paper towels or pine shavings/bedding
- Clean mouse cages with bedding
Acclimation to test conditions
For this project, collection of body weights for establishing growth curves are accomplished within the mice production rooms. Alternatively, however, mice may be obtained at weaning (3 or 4 weeks of age, depending on strain, DOB +/- 3 days) from production rooms, and kept in the laboratory mouse room until needed at prescribed age for weighing.
a. The mice are weighed early in the morning at the same time and day every week in the production rooms, so as to take advantage of the fact that the mice are normally calmer or asleep at this time. Alternatively, mice in their home cages are brought into a separate weighing room the same time in the morning on a weekly basis using a transport cart. To facilitate the process, the weighing room door is closed and the ambient noise is kept to a minimum to prevent undue excitement and unwanted escapees, especially when weighing "jumpers" or unusually nervous or agitated mice.
b. The top-loading balance is tared or zeroed with the lily tub (which may be lined with absorbent paper towel or bedding, and with/out cover) on top.
c. Mouse cages are carefully hand carried from service racks, where they are normally kept, to mobile changing station containing the top-loading balance.
d. Each mouse is gently picked up via its tail using a long metal forceps and placed inside the lily tub for weighing.
e. After weighing, each mouse is placed in a new clean cage along with its mates and then the cage is carefully hand-carried back to its designated rack.
For growth curves: weekly body weight starting at 3 wks up to 16 wks of age.