A Comparison of GreenFeed and SimpleScan Gas Measurement Systems

August 22, 2023

SimpleScan– is a “sniffer” that passively measures gas concentrations of methane, carbon dioxide, and optionally hydrogen and oxygen near an animal’s nose. Data is measured on a 1-second basis and automatically processed using our complex algorithms, which makes it easy for users to gather and interpret data.

The major consideration when using the SimpleScan is that gas emissions from the cattle’s nose are diluted 10 to 100-fold by ambient air before the air intake probe collects a small subsample for concentration measurement. The significant and unknown dilution rates can systematically and very significantly bias the concentrations making it impossible to measure the amount of gas emitted. We have also found that SimpleScan produces significantly greater between animal variation compared to flux measurements and in published field testing, SimpleScan animal rankings do not correlate well with Flux-based animal rankings (r2<0.10). Therefore, we do not endorse SimpleScan’s use for determining mass fluxes from animals or ranking animals within a herd of animals.

However, it is still possible to use SimpleScan to detect a number of education and relative changes in concentration changes over time. The system can output the ratios of methane to carbon dioxide, carbon dioxide to oxygen, and methane to hydrogen, which may provide a relative indication of changes in animal health, feed intake, dietary changes, and treatment effects which could be useful for high-level screening purposes. SimpleScan is easier and less expensive to install than GreenFeed and therefore may be useful as a qualitative screening tool.

GreenFeed – is a portable flux measurement system that actively collects all air emitted by the animal when using the machine. GreenFeed uses a fan to generate an attraction air flow rate that is 1,800 times more powerful than the air intake in SimpleScan. Almost all of the emitted gasses are collected and total air volume is measured in the GrenFeed, which allows measurement of the mass flux of gas (i.e., amount per unit of time) emitted by the animal. The high air intake rate and GreenFeed sensors (e.g., head proximity, airflow, wind, etc.) result in minimal unknown dilution of the emitted gasses. GreenFeed can be used in a variety of applications, from emission phenotyping to evaluating diets and nutrition to measuring metabolic heat production. GreenFeed is the global standard for monitoring methane emissions and produces standardized results that are directly comparable across units and farms.

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SimpleScan Advantages

  • Easy installation—Adapt to an existing feed trough (e.g., a milking robot or concentrate feeder). The air intake probe can be easily fit in most locations, and the sampling box can be attached near the unit for easy measurement
  • The unit is less expensive than a GreenFeed unit
  • Sample a large number of animals at a low cost
  • Greater animal adoption
  • Less maintenance and fewer consumables
  • Minimal calibration requirements
  • May be able to provide limited information on animal health and behavior

GreenFeed Advantages

  • Provides an accurate and quantitative, universally standardized flux-based emissions measurement
  • Data directly comparable across locations
  • Between animal variability is a true representation of the variability across a herd
  • Well monitored and supported by C-Lock with expert data review
  • Recognized as an accredited methane emissions monitoring method by USDA, Verra, and national inventories
  • Over 400 publications using Greenfeed, well accepted in the scientific community
  • Diverse applications from evaluating diet effects, feed additives, genetic evaluation, energetics, and whole herd monitoring
  • Easily implemented in extensive grazing and confinement systems

SimpleScan Disadvantages

  • Neither precise nor accurate—produces 5 to 20 times more between animal variability than flux approaches
  • Results cannot be standardized on an absolute basis
  • Cannot be universally standardized and compared across locations–because of highly variable dilution
  • Unsuitable for ranking animals by emissions–very weak animal ranking correlations have been found between Sniffer and flux bases methods (R < 0.05 to 0.12 )
  • Sniffer is highly influenced by animal behavior (e.g., head position) and environment mixing conditions (e.g., windspeed)
  • More of a qualitative than a quantitative tool
  • Sniffer is completely inadequate ranking by animals for Carbon Dioxide emissions
  • Errant and low-quality data that may increase data acquisition costs
  • Data is too erroneous for use in national inventories and methane prediction studies

GreenFeed Disadvantages

  • More difficult to install—requires set-up of the GreenFeed unit
  • More maintenance required
  • More expensive (on a per unit basis)
  • Decreased animal throughput compared to SimpleScan
  • Some animals may not use the system