# Novel OA-ICOS Sensor for Real-Time Quantification of Enteric Methane from Ruminants

## TL;DR

A new sensor system was developed to measure methane emissions from cows in real time, helping track greenhouse gas emissions from livestock.

## Contribution

A novel OA-ICOS sensor with a spindle-shaped cavity structure enables rapid and stable real-time methane detection from ruminants.

## Key findings

- The sensor achieved a 3-second response time and a detection limit of 0.07 ppm for methane.
- Daily methane emissions from Simmental cattle averaged approximately 311.83 liters.
- Methane emission peaks correlated with feeding times, showing a double-peak pattern.

## Abstract

What are the main findings?
A sensing system for measuring methane emissions from ruminants has been developed, enabling real-time detection of methane (CH4).A spindle-shaped integrating cavity structure is designed to achieve rapid gas concentration replacement and a fast response to changes in gas concentration.

A sensing system for measuring methane emissions from ruminants has been developed, enabling real-time detection of methane (CH4).

A spindle-shaped integrating cavity structure is designed to achieve rapid gas concentration replacement and a fast response to changes in gas concentration.

What are the implications of the main findings?
An estimation of daily methane emissions from cattle rumination was conducted, and a correlation analysis was performed between characteristics of methane emission peaks and feeding times.

An estimation of daily methane emissions from cattle rumination was conducted, and a correlation analysis was performed between characteristics of methane emission peaks and feeding times.

Methane (CH4) is a potent greenhouse gas, with livestock rumination being a significant contributor to global emissions. This study developed a real-time monitoring system utilizing Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) to simultaneously track rumination behavior and CH4 concentrations in cattle breath. By optimizing the off-axis integrated cavity structure and implementing a specialized environmental control system, we enhanced stability and detection accuracy, achieving a rapid 3 s response time to dynamic concentration changes. Laboratory stability tests and Allan deviation analysis demonstrated a minimum detection limit of 0.07 ppm. Continuous field monitoring of Simmental cattle revealed a daily methane production of approximately 311.83 L. The emission rates exhibited a distinct double-peak pattern heavily influenced by feeding schedules. Furthermore, a positive correlation was observed between the time elapsed post feeding and both the frequency and intensity of methane emission peaks. This method enables highly dynamic, stable, long-term monitoring of greenhouse gas emissions from ruminants, providing a robust tool for quantifying emissions and informing scientific feeding practices.