‍Daily Checks

• Animal Monitoring: Visually inspect animals twice daily (morning and afternoon) to ensure they are acclimating properly.

• System Health: Monitor real-time RER readouts; values below 0.7 or above 1.3 may indicate cage lid leaks or gas line issues.

• Supplies: Check that food hoppers and water sippers are filled and not blocked.

• Software Warnings: Regularly review the Oxymax software warning log for any hardware or status errors.

Consumables & Hardware

• Drierite (Desiccant): Replace desiccant columns when approximately 2/3 of the column has been consumed (indicated by a color change from blue to pink).

• Ammonia Filters: Monitor and replace ammonia traps according to usage levels.

• Particle Filters: Monitor and replace them based on usage levels.  

• Water Lines: Flush water lines and rinse thoroughly with de-ionized water after each study.

Long-term Maintenance

• Nafion Tube: The nafion tube should be replaced approximately every 3 years to ensure proper humidity levels.

• Soda Lime: Check and replace as needed to ensure effective CO2 removal for sensor zeroing.

• Mass Flow Controllers: Recalibration or replacement may be needed if flow readings drift, and they are recommended for service every five years.

Calibration & Validation

• Gas Sensors: Perform a two-point calibration at the start of every experiment. If an experiment lasts longer than seven days, recalibrate every seven days.

• Leak Checks: Conduct regular leak checks on reference air and animal cage driers using the built-in Oxymax Sample Pump Diagnostic tool.

• Annual Maintenance: Schedule an annual professional preventive maintenance visit from Columbus Instruments and for system level calibration.  

Cleaning & Care

• Cage Components: Wash and disinfect cage lids, bottoms, and food hoppers immediately following animal removal.

• Handling: Inspect lids and cage bottoms for cracks daily, as even minor damage can skew metabolic data.

• Tubing Seals: If a connection appears loose, trim 1 cm from the end of the tubing with a sharp knife to restore a proper seal; avoid over-tightening fittings.

Gas Sensor & Calibration Maintenance

• Drift Prevention: High-precision NDIR sensors virtually eliminate drift, but regular automated fresh-air reference checks are required to maintain accuracy.

• Recalibration Frequency: While the metabolic monitoring system is built for stability, periodic two-point calibrations using certified gases (e.g., 20.50% O2 and 0.50% CO2) are recommended to ensure the rodent calorimetry system remains within specification.

• Sensor Lifespan: Electrochemical oxygen sensors are consumable parts that require more frequent replacement than Zirconia or Paramagnetic options.

Consumable Management

• Drierite (Desiccant): This must be monitored to ensure it remains blue; once it turns pink, it is exhausted and will allow moisture to interfere with mouse indirect calorimetry readings.

• Soda Lime (CO2 Scrubbing): This should be white; if it turns purple or brown, it must be replaced to prevent CO2 buildup from skewing the metabolic phenotyping system data.

• Sample Drying: Ensure the integrated sample drying system is chilling correctly (typically down to 4°C) to remove humidity before gas enters the metabolism and behavior lab equipment.

Physical Cage & Feeding Maintenance

• Cleaning: Because the metabolic cage housing system uses standard IVC cages, they should be sanitized regularly to maintain animal welfare and remove any debris that could block infrared beams.

• Activity Beams: Periodically wipe the infrared beam arrays on the X, Y, and Z axes to ensure the cage monitoring system accurately tracks locomotor activity and sleep patterns.

• Feeder Inspection: For the overhead pellet feeder, check for bridging or stuck pellets to ensure the home cage monitoring system continues to record feeding events uninterrupted.

System Integrity Checks

• Leak Testing: Periodically inspect lid seals and gas line connections, as even minor leaks in the mouse metabolic cage system can cause the RER to fall out of the valid biological range.

• Pump Flow Rates: Verify that the lab animal monitoring system pump is maintaining the flow rate used during calibration to prevent measurement errors.

Daily Mechanical Checks

• Food Level Monitoring: Ensure the spring-loaded plate in the central feeder is moving freely; if it sticks, the animal cannot access the food, which will skew the mouse's indirect calorimetry data.

• Scale Zeroing: Ensure the spill cup beneath the feeder is not touching the cage floor or bedding, as this can prevent the load cell from accurately tracking consumption in the metabolic phenotyping cage.

• Tunnel Inspection: Quickly inspect the entry tunnel for any bedding that might have been pushed in, which could interfere with the animal's path to the food.

Post-Run Cleaning

The most important part of the metabolic and behavioral cages maintenance is cleaning the exit tunnel.

• Rib Cleaning: Use a small brush to remove fine powder particles from the specialized internal ribs. These ribs are designed to shake loose crumbs off the animal's fur; if they become clogged with grease or old food, they lose their effectiveness.

• Spill Cup Sanitization: The secondary outer hopper (the spill cup) must be thoroughly cleaned after every run to remove any oily residue from high-fat diets used in the mouse metabolic phenotyping system.

Load Cell & Scale Calibration

• Mass Calibration: At the start of every new study, use a certified calibration weight to span the food and water scales. The rodent calorimetry system software guides you through this process to ensure the scales are reading down to the milligram.

• Water System Flush: If your mouse metabolic system uses the Volumetric Drinking Monitor (VDM), flush the lines with a mild sanitizing solution followed by distilled water to prevent algae or mineral buildup in the sensors.

Gas Path Maintenance

• Desiccant Check: Inspect the Drierite (blue) and Soda Lime (white) in the gas sampling path. If the Drierite has turned pink, moisture is reaching your sensors, which will cause drift in your metabolic phenotyping system data.

• Filter Replacement: Replace the small particulate filters at the cage gas inlets to prevent powdered diet dust from entering the delicate gas analyzers of the lab animal monitoring system.

Summary: Maintenance Checklist

Separation Funnel & Wire Floor Maintenance

• Debris Removal: Check the wire-mesh floor daily for trapped feces or food clumps that could prevent urine from flowing into the separation funnel.

• Funnel Coating: Regularly ensure the funnel's internal surface is clean and smooth; any residue can cause urine to bead rather than flow, delaying automated voiding detection.

• Sanitization: Use non-residue cleaners on the funnel and wire floor to prevent chemical interference with sensitive urine biomarkers or metabolomics samples.

Load Cell Calibration & Care

Zeroing the Scales: Before each run, ensure the collection vials are properly seated on the high-precision load cells and zeroed through the software.

• Clearance Check: Verify that the collection vials are not touching the sides of the stand or the funnel exit, as any mechanical contact will skew the weight data recorded by the metabolic monitoring system.

• Load Cell Protection: Avoid pressing down heavily on the vial platforms during cleaning, as these scales are calibrated for milligram-level sensitivity (+/- 0.005g).

Feeder & Tunnel Cleaning

• Rib Cleaning: The specialized ribs inside the narrow tunnel feeder must be kept free of oils and food dust to effectively brush the animal's fur and prevent contamination of the urine funnel.

• Spill Cup Emptying: Regularly empty the spill cup located beneath the tunnel feeder to ensure food weight tracking remains accurate, and crumbs do not overflow into the waste area.

Gas Path & Moisture Control

• Desiccant Maintenance: Because the waste cage environment can have higher humidity due to open urine vials, monitor your Drierite (desiccant) frequently.

• Sample Dryer Inspection: Ensure the integrated sample dryer is cooling correctly (typically down to 4°C) to remove moisture from the air stream before it reaches the mouse indirect calorimetry sensors.

Urine Preservation System (Add-on Feature)

• Cooling Plate Check: If using the urine freezing option, verify that the chilled plates are reaching the target temperature before placing collection vials.

• Vial Charging: If using chemical preservatives in the vials, ensure they are added in exact volumes to be subtracted from the final weight recorded by the lab animal monitoring system.