Comprehensive Lab Animal Monitoring System (CLAMS)

The MMRU has two Oxymax calorimetry systems (Columbus Instruments) permitting either one experiment with up to 28 mice, or two experiments with up to 16 and 12 mice, respectively, to be run concurrently. The two systems have different configurations: automated food access control and telemetry are available on the 16-cage system, and voluntary wheel running capability with food monitoring available on the 12-cage system.

The calorimetry system monitors O2 and CO2 concentrations at the inlet and outlet ports of a chamber through which a known volume of air flows. This information enables the calculation of O2 consumption, CO2 production, and respiratory exchange ratio (or RQ), providing accurate and reproducible data on whole body energy expenditure.

The Columbus Instruments Opto M3 is a multi-channel activity monitoring system for the continuous measurement of ambulatory and total movement. Infra-red beams are projected at 0.5" spacing across the cage on 2 levels. During movement, the beams are broken by the mouse, and this sends signals to the central computer. The beams can detect movement along both the X (length of cage) and Z (height) axes. The system is a component of the calorimetry cages.

Independent studies (see Pack et al. in references) have determined the relationship between activity and sleeping patterns. This information is automatically generated for your data and is provided along with other CLAMS results. 

Twelve of these cages can be modified to include free running wheels. The system records the number of revolutions, distance, and speed run, and the time of day when the activity occurs. Due to the diameter of the wheels, measurements are limited to mice weighing less than approximately 35 g.

• System capacity for this parameter: 12 mice
• Maximum housing duration within these cages: 1 month
• Equilibration period recommendation: 2 to 3 days
• Weight range: 10 to 70 g (35 g for running wheels)

Columbus Instruments has teamed with Mini Mitter® for continuous monitoring of core body temperature within the CLAMS. The transmitting device does not require batteries, and thereby eliminates the time and expense involved in refurbishment. Through the use of the ER-4000 Energizer-Receiver system (a component of the calorimetry cages), the transmitter (G2 E-Mitter; 1.5g weight; surgically implanted within the abdominal cavity) is energized via magnetic impulses. The device continually transmits body temperature information that is recorded by the programmed computer.

• System capacity for this parameter: 16 mice
• Maximum housing duration within these cages: 1 month
• Recovery from surgery: 2 weeks
• Equilibration period recommendation: 2 to 3 days
• Weight range: 20 to 70 g

The CLAMS system monitors the amount of food consumed by the mouse, and the frequency and duration of each meal. The combination of these parameters enables investigators to assess appetite and satiety.

Food, in powdered form, is placed in a feeding assembly that rests on a precision modified Mettler Toledo Balance (0.01-210 g range). The mouse accesses food by eating from a spring-loaded feeder through an anti-foraging guard; this guard also prevents full body access to the dish. (For mice that weigh less than 12 g this is not always effective.)

Spillage is accounted for by a larger dish, beneath the main food cup, that catches anything that spills over the edge. This spillage collection cup also rests on the balance, and because spilled food is not accessible to the mouse, the mass remains on the balance, and is not recorded as “food eaten”. The mass of food consumed is monitored continuously.

Feeding bout information is gathered by disturbances on the balance, following defined set values (as determined by the investigator) for "minimum valid weight" and "maximum idle time.” "Minimum valid weight" is defined as the minimum amount of food that must be consumed in order to record a feeding event. This value can be as little as 3 mg. "Maximum idle time" defines the time that must elapse between balance disturbances to define separate meals. Because food is eaten by the mouthful, the balance often settles between bites. By setting a time value for between bites, a series of bites can be grouped as a meal. Each meal is therefore associated with a start time, finish time, and mass of food consumed. Special Teflon feeders are available for use with high fat diets.

System capacity for this parameter: 48 mice (and additional 28 of can simultaneously provide indirect calorimetry)

• Maximum housing duration: indefinite depending on availability
• Equilibration period recommendation: 2 to 3 days
• Weight range: 10 to 70 g