What is Methane (CH4)?
Methane is a colourless, odourless gas occurring abundantly in nature and as a product of certain human activities. Its chemical formula is CH4. Globally, it is the second most important greenhouse gas (GHG). Its contribution to global warming is estimated at 28 times that of carbon dioxide, over a 100 year period. Once produced, methane persists in the atmosphere for around 12 years after which it is eventually broken down into carbon dioxide and water.
Ruminant livestock have a unique ability to convert grass into high quality sources of dairy and meat protein for human consumption. In the rumen or forestomach of ruminant livestock there is a microbial ecosystem with bacteria, archaea, protozoa and fungi, collectively known as the rumen microbiome. This microbial ecosystem allows ruminant livestock to obtain nutrition from plant matter. Biogenic methane is a natural by product of this process, it is commonly known as enteric methane. It is estimated that 90-95% of enteric methane is expelled from the rumen in the breath of the animal (eructation) with the remainder a product of flatulence.
The GreenFeed System used to investigate methane emissions at pasture and indoors
How much methane does agriculture produce?
A 500kg beef animal on a high concentrate diet produces 230 g methane per day and a 550kg dairy cow grazing on pasture emits about 320-330 grams of methane per day.
The reporting of Irish GHG emissions in 2020 attributes 58% of Irish agri emissions to methane produced by the rumen of cattle and sheep. A further 10% of national agricultural emissions originated from methane associated with the storage of manure and slurry. This is produced by microbes that have passed through the animal in the faeces. Methane associated with ruminant livestock production accounts for two-thirds (68%) of Irish agricultural GHG emissions.
Portable accumulation chambers (PAC) for measuring methane emissions from sheep
Methane arising from enteric fermentation accounts for just below 19% of our national GHG emissions. Reducing the volume of methane originating from ruminant livestock will be required for Ireland to adhere to both EU 2030 emissions reduction targets and national ambitions to be carbon neutral by 2050.
- Animal breeding - breed animals which emit less methane; this is a long term strategy
- Dietary supplementation/management - feeding of methane reducing supplements
- Improved animal health – a healthy animal will be more productive during its lifetime
- Lifetime performance/age at slaughter – slaughtering prime beef animals at a younger age will reduce the volume of methane produced over the animal’s lifetime.
Please note: All farms are unique and please contact your local Teagasc advisor for your individual enquiries before carrying out any solutions listed above
The following research is ongoing or nearing completion:
- RumenPredict – Linking the composition of the rumen microbiome to methane emissions and feed efficiency in beef cattle. Funded by ERA GAS and ERA NET.
- MASTER – Increasing the understanding of the relationship of the rumen microbiome and methane emissions in sheep and cattle. Funded by EU Horizon 2020.
- GREENBREED – Developing breeding strategies for low methane emitting cattle and sheep. Funded by the Department of Agriculture, Food and the Marine.
- VistaMilk – Quantifying and understanding methane emissions of dairy cows in a pasture based system. Funded by VistaMilk SFI Centre.
- METH-ABATE - Development and validation of novel technologies to reduce both enteric and manure associated methane emissions from pasture based Irish agricultural systems. Funded by the Department of Agriculture, Food and the Marine.
- SEASOLUTIONS – Investigating the effects of seaweeds and seaweed-ingredients to reduce enteric methane emissions from pasture-based sheep, cattle and dairy cows. Funded by ERA GAS and ERA NET.
- On-going work at Teagasc Grange is looking at the effects of management history on the interaction between the host animal, the microbial community of the rumen (its rumen microbiome) and CH4 production. The focus is on dietary manipulations in early life, when the rumen community is developing, as well as later diet transitions. The research forms part of an international FACCE-JPI project called RumenStability. Further work to collate and analyse experimental data on animal performance, N utilisation and CH4 emissions in ruminants as part of the international GLOBAL NETWORK project is also on-going.
You can read more about the AGRI-I Methane Project on the AGRI-I website