Projects - L (Lisanne) Koning MSc

PhD project: The effect of fresh grass and grazing on enteric methane emission of dairy cattle 

Ruminants account for about one-third of anthropogenic methane (CH4) production worldwide. Enteric CH4 is produced during fermentation of feed by microbiota, mainly in the rumen and to a lesser extent in the hindgut. The rumen microbiota composition and activity is influenced by animal and environmental factors, with diet composition being a primary factor. Grass is a major component in the diet of dairy cattle, and hence ruminal fermentation of grass is an important source of enteric CH4 production in cows. However, there is relatively limited knowledge about the relationship between enteric CH4 emission and both fresh grass quality and grassland management. Therefore, for this PhD project a multiannual research approach is applied to study the effect of fresh grass characteristics and grassland management on enteric CH4 emission of dairy cattle. Although grazing systems are used worldwide, quantifying and mitigating enteric CH4 emission from these systems can be challenging. One of the main challenges in quantifying enteric CH4 emission is to capture the diurnal emission pattern of ruminal CH4, which can vary by a factor of four throughout the day. This holds specifically for conditions where less operational control is possible (e.g. during grazing). In these situations, the GreenFeed system can be used, which enables short-term CH4 emission measurements at several moments (i.e. system visits) during the day. A significant problem with these short-term measurement techniques is that it is currently unknown how to optimally use spot measurements of enteric CH4 emission from dairy cattle, to ensure they accurately capture the full diurnal emission pattern. Therefore, the second objective is to evaluate how best to use the GreenFeed system to quantify enteric CH4 emission during grazing.