Different growing conditions based on season and weather, and differences in use or management, such as grazing systems and mowing regimes, create a wide range of grass qualities.
Grassland management has a direct effect on the quality of the fresh grass and thus on CH4 and NH3 emissions from dairy cattle. These mechanisms are largely known for NH3, but less so for methane emissions. In order to be able to reduce CH4 and NH3 simultaneously on dairy farms, it is necessary to understand these mechanisms.
For this reason, the grazing trial examines the effect of grass quality on methane
emissions. A total of three groups of 16 cows are used for this in April, June and August (test schedule A) and two groups of 16 cows in May, July, September (test schedule B).
Final round of trial schedule A.
Various trial plots with grassland have been laid out on Dairy Campus. In three rounds of four weeks each, methane emissions are measured in 100% grass silage, 100% fresh grass in the barn, and grazing day and night in three groups of 16 cows.
Round 1: Spring (April / May)
Round 2: Summer (June / July)
Round 3: Autumn (August / September)
Round 3 started on Tuesday 11 August. The last round for measuring the methane
emissions from short and longer pasture grass will take place in September
(pilot scheme B).
In this way, insight is gained into the various forms of grassland use, but also a
picture of seasonal effects is created. It is a multi-year trial that will also focus on the effect of herb-rich grassland in the future.
Outside grazing & measuring
The methane emissions of the individual dairy cow are measured with the GreenFeed. Methane is mainly produced by microbes in the rumen and exits mainly through the nose and mouth of the cow. An analysis of the exhaled air gives a good indication of the methane emission. Three GreenFeeds are standard available in the Dairy Campus feeding shed. For this study, two mobile units were also placed outside the cows.
Due to the high temperatures, the times of the day and night pasture group have been adjusted in recent days. The cows have a siesta in the barn for a few hours at noon. Because they spend the rest of the hours, including the night, on the meadow, the 100% meadow grass ration can be preserved.