Recent research highlights the benefits of C-Lock’s GreenFeed system for measuring methane production in dairy farms, highlighting that mass flux measurements provide more reliable data for research and decision-making than traditional concentration-based sensors.
As the livestock industry moves toward more accurate methane measurements, one distinction is becoming increasingly important: the difference between measuring methane concentration and measuring methane production. Both provide insight, but are not interchangeable. New research also shows why measuring methane as a mass flux provides a more reliable basis for research, genetic selection, and on-farm decision-making.
A recent five-month study conducted in Switzerland evaluated methane “sniffer” sensors installed within automatic milking systems (AMS) and compared them to C-Lock’s GreenFeed emissions monitoring system, a widely used tool on farms that measures methane production in grams per day. This result supports an important message. While concentration-based measurements are highly sensitive to sensor placement and animal behavior, GreenFeed’s mass flux approach provides greater consistency and reliability.
concentration and productivity
Most AMS sniffers measure the concentration of methane (ppm) in the air near the cow’s muzzle while the cow is eating during milking. These measurements are attractive because they can be collected frequently with minimal disruption. However, concentration measurements are influenced by factors unrelated to the amount of methane actually produced by the cow, such as the distance between the cow’s muzzle and the sensor, head movement during milking, and airflow within the barn.
GreenFeed takes a different approach. Rather than relying on concentration alone, we measure both methane concentration and airflow in a controlled sampling area around the cow’s head. This allows us to calculate the methane mass flux (the amount of methane released over time). From a practical standpoint, GreenFeed measures what matters most: how much methane cows actually produce, not how concentrated methane happens to be at any one point in the universe.
Test sensor placement
To understand how important sensor placement is, researchers installed nine sniffer nozzles in a 3×3 grid above the feed bins within the DeLaval AMS. At the same time, GreenFeed units were installed in the same barns, allowing them to measure methane production from the same cows.
Data were collected from 107 lactating dairy cows across three breeds over a period of 154 days. This study showed that methane concentration measurements varied significantly depending on the sniffer nozzle used. Higher and more consistent values were recorded at locations closer to where dairy cows normally exhale during feeding, whereas sensors further away, i.e. closer to the wall, recorded lower concentrations and showed greater variability.
This change is not easy. This means that two sniffers measuring the same cow at the same time can give completely different results, depending purely on where the sensor is placed.
GreenFeed as a stable benchmark
When the researchers compared sniffer measurements to GreenFeed’s methane production, the correlations were generally moderate and strongly dependent on nozzle location. The central sniffer location was the closest match to GreenFeed, but it was still not a perfect match.
Reproducibility (the ability to obtain consistent results from the same cow over time) improved with both systems when measurements were averaged over time. However, GreenFeed made fewer assumptions about animal position and airflow and showed strong stability, whereas Sniffer required careful positioning and long averaging times to achieve comparable consistency.
This distinction is important for applications such as evaluating feed, testing feed additives, and benchmarking whole herd emissions. A system that directly measures methane production reduces uncertainty and simplifies interpretation.
Cow Ranking: Where Accuracy Really Matters
One of the most valuable uses of methane data is to rank cattle based on emission intensity for research and genetic selection. The study found that cow rankings varied depending on which sniffer location was used, with only low to moderate agreement with GreenFeed rankings.
This highlights a real risk. If rankings depend on sensor placement, they may reflect barn geometry or animal behavior rather than true biological differences. GreenFeed’s mass flux approach circumvents this problem by capturing total methane emissions during each visit, providing a reliable reference when ranking animals and validating low-emission strategies.
What this means for the industry
Sniffer systems have a role in high-throughput data collection, especially if carefully installed and standardized. However, this study revealed that measuring concentration alone introduces additional uncertainties, especially in dynamic environments such as automated milking systems.
GreenFeed continues to be used as a benchmark for enteric methane measurements around the world because it allows direct measurement of methane production, rather than inferring emissions from concentration alone. As the industry moves toward data-driven emissions reductions, tools that provide reproducible, comparable, and biologically meaningful data will be essential.
Take-out
Not all methane measurements tell the same thing. Concentration data can be valuable information, but where decision-making relies on accuracy, such as in research, breeding, or sustainability programs, measuring methane production via mass flux provides a clearer and more reliable picture. This study confirms what many researchers already know: How methane is measured is just as important as how often.
This article will be published in an upcoming Special Focus Publication on Animal Health.
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