Agriculture has a large contribution to the emission of greenhouse gases. Studying mitigation strategies requires reliable data of CH4 production of individual animals. Suggested is that a relationship exists between individual rumination activity and CH4 emission, since both are driven by the dry matter intake and milk production of the cow. The aim of this study was to explore the possibility of using rumination time as an indicator for enteric CH4 production of dairy cows.
The anthropogenic emission of methane (CH4) is mainly related to enteric fermentation in ruminants. Different studies investigated mitigation strategies, like nutritional adjustments or breeding programs, to reduce the CH4 production of ruminants. Suggested is that a relationship exists between individual rumination activity and CH4 emission, since both are driven by the dry matter intake and milk production of the cow. The aim of this study was to explore the possibility of using rumination time as an indicator for enteric CH4 production of dairy cows. If so, a large number of CH4 production records of individual cows becomes available, because of the large use of rumination activity sensors in the dairy sector. With this data the effect of different mitigation strategies on the individual CH4 production can be studied more accurately.
Data of rumination activity and CH4 and carbon dioxide (CO2) concentrations in exhaled and belched air of 209 cows were analysed. Rumination data were collected by neck collars, which estimate the time spend on rumination, whereas CH4 and CO2 concentrations were determined in breath samples of individual cows, collected during milking. The CH4 and CO2 data measured by the gas analyser fluctuated a lot between cows and within cows. For the analysis, the data were adjusted in different steps to produce more accurate data and second, the correlation coefficient (r) of the CH4 production and rumination activity data was calculated per cow. The r between the adjusted CH4 data and daily time of rumination varied from -0.704 to 0.615 across cows and was on average -0.017.
In contrast with the hypothesis, no relationship between individual rumination activity and CH4 production was shown. The behaviour of the cow and position of the inlet filter of the gas analyser, of the cow and the cows’ head all affect the gas concentration measured by the gas analyser.
From this study it can be concluded that it seems not possible to use rumination time as an indicator for enteric CH4 production in dairy cows. When the measuring method will be improved and become more precise and reliable data of individual enteric CH4 production can be obtained, it might be possible to find a relationship with the rumination activity.
Student: EHA Dings
Supervisor: dr ir E Bokkers