Exploring indicators of genetic selection using the sniffer method to reduce methane emissions from Holstein cows

Area of Science:

• Animal Science
• Agricultural Science
• Environmental Science

Background:

• Methane (CH4) emissions from livestock contribute to greenhouse gases.
• Genetic selection offers a sustainable strategy to reduce enteric CH4 emissions in dairy cattle.
• Accurate and practical methods are needed to assess CH4-related traits for genetic improvement.

Purpose of the Study:

• To evaluate the CH4 to CO2 ratio (CH4/CO2) and other methane-related traits measured by the sniffer method as indicators for genetic selection of Holstein cows with lower CH4 emissions.
• To assess the on-farm applicability and reliability of the sniffer method for predicting methane-related traits across different lactation stages and parities.

Main Methods:

• Utilized the sniffer method to simultaneously measure CH4 and CO2 concentrations during milking.
• Calculated methane-related traits including CH4 emissions, CH4 per energy-corrected milk, methane conversion factor (MCF), and residual CH4.
• Analyzed two on-farm datasets to investigate model impacts, estimate genetic parameters, and compare repeatability and environmental effects.

Main Results:

• The methane conversion factor (MCF) could be reliably evaluated irrespective of body weight (BW) inclusion in the model.
• CH4/CO2 and MCF exhibited low heritability and moderate repeatability.
• Moderate genetic correlation was observed between milk yield and MCF, suggesting potential for simultaneous selection.

Conclusions:

• The sniffer method is applicable on-farm for evaluating CH4/CO2 and MCF.
• These traits demonstrate potential as indicators for genetic selection aimed at reducing CH4 emissions in Holstein cows.
• The study supports the use of on-farm measurements for developing breeding strategies for lower methane-emitting cattle.