Reduction of methane emission by dairy cows
Methane emissions from cows constitute more than half the global-warming impact of milk production. Methane is produced predominantly in the cow’s rumen as a result of microbial fermentation of feed components. In terms of global warming it is approximately 25 times more damaging than carbon dioxide. Reduction of methane emissions from cows will contribute substantially to reducing the ecological footprint of dairy production.
The Dutch dairy sector is aiming for a 30% reduction in greenhouse gasses by 2020 and this project will contribute to that goal via a four-pronged multidisciplinary approach. First, we are developing an indicator for methane emission from individual cows: this method will enable large-scale measurement of methane emissions. Currently we are measuring the methane of individual cows in climate respiration chambers and analysing milk samples from the same cows. Preliminary results indicate that about 70% of the variation in methane emissions between cows is related to differences in milk composition. Second, we are exploring the genetic variation in methane emissions between cows in order to quantify the potential of breeding measures to reduce methane emissions. At present, we are measuring methane in the exhaled air of cows in automatic-milking systems on commercial dairy farms. First results demonstrate that at least part of the variation in methane emissions between cows is of genetic origin. Third, we are characterising the composition and functioning of microorganisms in the rumen of the cow in order to quantify the effects of rumen dynamics on methane emissions. For this we analyse the microbial composition of rumen samples taken from the cows whose methane is measured in the climate respiration chambers. Initial results suggest differences in the activities of individual cow’s rumen microorganisms. Fourth, we are developing mechanistic models that will improve the understanding of how methane emission is influenced by the interactions between the genetics of the cow, the microorganisms in the rumen of the cow and cow feedstuffs. We are about to start an experiment in which we will explore these interactions in detail.
|Scientific papers in peer-reviewed journals||2015 Enteric methane production, rumen volatile fatty acid concentrations, and milk fatty acid composition in lactating Holstein-Friesian cows fed grass silage- or corn silage-based diets||View summary|
||2015 Indicator for methane emission in milk – fatty acids, volatile and non-volatile metabolites|
|Scientific papers in peer-reviewed journals||2016 Relationships between milk fatty acids profiles and eteric methane production in dairy cattle fed grass-or grass silage-based diets||View summary|