Do methane measurements from a laser detector and an indirect open-circuit respiration calorimetric chamber agree sufficiently closely?

In ruminant production, there is a need for inexpensive, convenient and practical methods for quantifying the amount of enteric methane produced by cows. The current study tested the level of agreement between a recently developed proprietary laser methane detector (LMD) and the indirect open-circuit respiration calorimetric chamber. The test was based on two different methods, these are: Pearson correlation and analysis of agreement based on the Bland and Altman methodology. The correlation coefficient of the LMD and the calorimeter chamber was high (r = 0.8) and positive. The Bland and Altman methodology demonstrates high level of agreement between measurements of the LMD and the calorimeter chamber. Further, inverse regression provided sufficiently close estimates of the chamber measurements based on LMD. However, in general the measurements by the LMD were numerically higher than those from the chamber. Further work is underway to examine the use of the LMD to measure enteric methane directly from cows.