The cubicle hood sampler: Design of a practical system for the measurement of dairy cows’ methane production rates

Monitoring methane production from individual cows is crucial for the implementation of greenhouse gas reduction strategies. However, monitoring methane production rates (MPR) under practical conditions and with acceptable levels of accuracy, intrusiveness, and throughput remains challenging. In this study, we present a renewed design of the Cubicle Hood Sampler (CHS) as a potential solution to this challenge. Placed in the cubicles, the CHS collects and analyses the methane content of the air exhaled by cows when lying down. The ability of four CHS units to recover known MPR was assessed in three series of recovery tests using a reference method (artificial reference cow (ARC)). For the fluxes tested, there were no significant difference in recovery rates (mean 110.5 ± 8.7%) between CHS units (p = 0.207), production rates (p = 0.080), and repetitions (p = 0.148). Recovery rates appeared not to be significantly different from 100% (p = 0.154), and root mean square error equated 35.0g, which is considered acceptable for MPR levels of 200 and 400g/day. Repeatability equated 0.94, showing the high repeatability and reliability across replicates. These results place the CHS as a promising tool for on-barn methane measurements. However, the radio frequency identification used to link measurements to specific cows did not yield sufficient levels of correct identification. Similarly, the monitoring of head poses was not satisfactory, and the CHS still requires further improvements to be made.