Your best bet is to collaborate with someone who has the correct equipment.  Oxygen consumption requires a lot of specialized equipment, including air pumps, oxygen sensors, water absorption columns (or water sensors for correction) etc.  It is not something you can just build.

Another option is to assess VO2 max as a function of exercise capability, if you have a treadmill for mice, you can develop an increasing speed protocol, where you can see at what speed the animal can no longer maintain running.   There are a lot of problems with this type of assay, including exhaustion before reaching top speed and confounding effects of the type of ramp (ramps tend to be stepped, so big differences in run time can often be due to the step in belt speed, not the fitness of the animal), but it would at least let you know whether it is worth finding a collaborator to look at actual oxygen consumption

Thank you very much sir

I wish this guideline will show me the proper way.