Technical note: validation of the GreenFeed system for measuring enteric gas emissions from cattle

Area of Science:

• Agricultural Science
• Environmental Science
• Animal Science

Background:

• Knowledge gaps exist in animal agriculture regarding greenhouse gas (GHG) mitigation strategies that maintain animal productivity.
• Uncertainties in emission rate measurement methods hinder accurate GHG mitigation.
• Accurate quantification of enteric methane (CH4) and carbon dioxide (CO2) is crucial for animal agriculture's environmental impact assessment.

Purpose of the Study:

• To compare the accuracy of a commercial GreenFeed (GF) system for measuring cattle enteric CH4 and CO2 emissions against established methods.
• To validate the GF system's performance using a mass flow controller (MFC) and a respiration chamber (RC).
• To identify potential discrepancies and areas for improvement in GHG emission rate measurements in livestock.

Main Methods:

• Comparison of CH4 and CO2 emission rates measured by the GreenFeed (GF) system.
• Validation against a mass flow controller (MFC) providing known gas release rates.
• Cross-validation with a respiration chamber (RC) for gas analysis.

Main Results:

• The GF system showed minimal differences compared to the MFC: 1% for CH4 (P = 0.726) and 3% for CO2 (P = 0.013).
• Differences between the GF system and the RC were also small: 1% for CH4 (P = 0.019) and 2% for CO2 (P = 0.007).
• A systematic offset error was identified for CO2, suggesting a potential correction factor.

Conclusions:

• The GreenFeed system provides accurate estimates of enteric CH4 and CO2 emission rates in cattle over short measurement periods.
• The GF system is a viable tool for assessing livestock GHG emissions.
• Further research is needed to account for all factors influencing 24-hour animal emission rates.