Modelling methane emission from dairy cows, barn, and storage

Saman Lashkari*, Frederik Rask Dalby, Christian Friis Børsting

*Corresponding author af dette arbejde

Publikation: KonferencebidragKonferenceabstrakt til konferenceForskningpeer review


There is a large variation among dairy farms in the productivity, feed intake, feed composition, and slurry management
in the barn and in outside storage, which affect emissions. The aim of the present study was to develop a model to
quantify enteric methane emission and emission from barn and storage based on diet composition, performance level
and farm management. The annual emission was modelled for a dairy farm with 200 cows (11.2 tons milk/cow/year
and 8,480 kg DMI/cow/year based on the Danish Manure Normative System). Slurry was removed every 28 d from a
barn with a ring-channel slurry storage under a slatted floor. Slurry was stored in an outside slurry storage with a natural
crust and without tent cover until field application (avg. ret. time of 3.2 months). Nutrient composition of feedstuffs
was obtained from Norfor feed table. Enteric methane was estimated based on DMI, fat (g/kg DM), and NDF (g/kg
DM). Nutrient composition of faeces was calculated based on feedstuff composition and digestibilities of organic
matter, sugar, starch, protein, and fat. Methane emission from slurry was estimated with the anaerobic biodegradation
model, which tracks organic matter conversion to methane in two steps: (1) hydrolysis of organic matter to VFA; and
(2) VFA conversion to methane and CO2 by methanogens. Hydrolysis rate constants were applied individually for
each organic matter component in the slurry (protein, fat, fibre, etc.). The hydrolysis rate constants were derived from
laboratory experiments with pig slurry incubated at different temperatures and are preliminary. Three diets with a wide
range of concentrate to forage ratios (49:51%; diet 1, 70:30%; diet 2, and 91:9%; diet 3) were used to investigate the
effect of extremely different diet compositions on emissions. Enteric methane emission was 55, 51, and 47 (tons/year)
in diets 1, 2, and 3, respectively, and methane emission from the barn was 6.0, 6.1, and 6.2, and it was 9.8, 9.4, 9.0
(tons/year) from the storage in diets 1, 2, and 3, respectively. These preliminary modelling results indicate that feed
composition has an impact on the total emission of methane, mainly due to differences in enteric methane.
Publikationsdato26 aug. 2023
Antal sider1
StatusUdgivet - 26 aug. 2023
74th Annual Meeting of European Federation of Animal Science
- Lyon, Frankrig
Varighed: 26 aug. 20231 sep. 2023
Konferencens nummer: 74


74th Annual Meeting of European Federation of Animal Science