High rate monitoring CH4 production dynamics and their link with behavioral phases in cattle

Microbial fermentation in the rumen produces methane (CH4) which is a loss of energy for ruminants and also contributes to global warming. While the respiration chamber is the standard reference for CH4 emissions quantification, daily CH4 production dynamics can be measured only by steps of 30 min and measurements on pasture are impossible. The alternative method using SF6 as tracer gas can be applied for grazing animals but provides average CH4 production values over at least several hours, making it impossible to measure short
term dynamics of rumen CH4 production with changing animal behavior along the day. Newly developed methods using CO2 as internal tracer gas extrapolate CH4 emissions from few short measurements. However, both CO2 and CH4 emissions fluctuate during the day depending on the behavior and the post-feeding times
questioning the validity of this method. Therefore, an innovative device was developed to monitor at a high
rate CH4 and CO2 emission dynamics in order to investigate the link between CH4 dynamics and the animal
behavior on pasture. Preliminary results showed the ability of the device to record differences in CH4:CO2
ratios and eructation frequencies according to the individual and the behavior. Results from complementary experiments in barn with animals fed contrasting diets regarding CH4 production (with and without linseed) and on pasture with different forage allowance will be presented in order to highlight how post-feeding time and grazing behavior impact CO2 and CH4 emission dynamics along the day.