Extending the Collection Duration of Breath Samples for Enteric Methane Emission Estimation Using the SF₆ Tracer...

Area of Science:

• Agricultural Science
• Environmental Science
• Animal Science

Background:

• Daily sampling for sulphur hexafluoride (SF₆) tracer technique to estimate ruminant methane (CH₄) emissions is challenging in extensive grazing systems.
• Alternative sampling strategies are needed to improve practicality and efficiency.

Purpose of the Study:

• To evaluate extended sampling periods as an alternative to daily sample collections for SF₆ tracer technique.
• To compare methane emission estimates using different sampling durations and systems.

Main Methods:

• Eight rumen-fistulated cows were fed lucerne silage under controlled conditions.
• SF₆ permeation tubes were used for dosing, with breath samples collected via harnesses.
• Two sampling systems (New Zealand - NZL, and Argentina - ARG) were tested across daily, 5-day, and 10-day collection periods.

Main Results:

• The NZL system demonstrated higher sampling success (97.3%) compared to the ARG system (79.5%).
• Methane emission estimates were consistent across daily (114 g d⁻¹), 5-day (110 g d⁻¹), and 10-day (111 g d⁻¹) sampling periods using the NZL system.
• The NZL system provided more consistent CH₄ emission estimates than the ARG system.

Conclusions:

• Extended sample collection protocols for SF₆ tracer technique may be feasible for estimating ruminant methane emissions.
• Further evaluation under grazing conditions is necessary to validate extended sampling and compare collection systems before making recommendations.