Quantifizierung der Methanemissionen bei Rindern mit Hilfe des fäkalen Biomarkers Archaeol (MethanA)

Contact: Prof. Dr. Cornelia C. Metges

Duration: 2013-2017

Funding: Bundesministerium für Ernährung und Landwirtschaft

Methane emission of German Agriculture is mainly derived from cattle where dairy production is the main emitter (77%). The greenhouse gas methane is produced during rumen digestion of plant fibre and the methanogenic microorganisms Archaea are responsible to produce methane from CO2 and H2. In the project we established and improved a GC-MS-based analytical method to quantify fecal archaeol, an archeal membrane lipid, from ruminants. A further aim was to explore its suitability as an indirect methane marker. We measured the methane emission of 10 lactating German Holstein cows from the research dairy herd of the CAU University of Kiel in the respiration chambers of the Leibniz Institute for Farm Animal Biology. In parallel feces was collected and the archaeol concentration was measured. We tested practicality, reproducibility, and precision of different archaeol extraction protocols and investigated and compared two techniques of archaeol GC-MS quantification. We showed that lipid extraction using ultrasound was more tedious and 50% less efficient than lipid extraction using the Soxhlet method. Positive chemical ionization was superior for the GC-MS quantification of archaeol. We confirmed the absence of archaeol in various feedstuffs. Our results further show a relatively wide variability of fecal archaeol concentration in dairy cows’ fed the same diet. The archaeol concentration was lower in rumen content than in the feces and was affected by diet composition. The kinetics of fecal archaeol concentration depend on the timing of feeding and the amount of feed intake. More systematic investigations are necessary before the feasibility of fecal archaeol as indirect methane marker can be established.