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05.01.15 Reducing GHG emissions from livestock - best practice and emerging options

5th Jan 2015

This report has been released from the livestock research group of the Global Research Alliance on Agricultural Greenhouse gases and the Sustainable Agriculture Initiative (SAI) platform.

As we have been focussing on livestock and especially the role of diets in GHG emissions. Livestock pays an important role in climate change. Livestock systems including energy use and land use change along the supply chain, accounted for an estimated 14.5% of total global greenhouse gas
emissions from human activities in 2010. More than half of these (about 65%) are related to cattle. Direct emissions from livestock and feed production constitute 80% of total agricultural emissions and as such need to be part of any effort to reduce the contribution of food production to global
climate change.

This report describes 6 broad areas where on-farm emissions from animal production can be reduced, broken down into different intervention options. Management strategies have been
broken into:

Improving feed quality and digestibility

Improving animal health and husbandry

Manure management: collection, storage and utilisation

Precision livestock farming

Feed and nutrition

Feed and nutrition directly affects an animal’s productivity and health status and can strongly influence GHG emissions per unit of product. When dealing with ruminants, a large fraction of GHG emissions is caused by enteric methane production in the rumen. There are multiple ways in which feed
quality and digestibility can be improved in all production systems, which will
in turn improve rumen efficiency. As well as improving quality, there are substitutes and supplements that have been developed to increase resource efficiency and change fermentation processes in
the animal to decrease GHG emissions intensity. The efficacy of upscaling these approaches however, may in some instances, conflict with food security if crops are used to feed animals instead
of humans directly.

Improving forage quality

Grazing management and improving forage quality by changing forage species can equally contribute to an improved diet formulation in extensive systems which can substantially increase feed efficiency and production. Reductions in emissions intensity of 30% are considered possible in systems that currently use very low quality feed.

Dietary improvements and substitutes

Feed substitutes can change fermentation processes in the rumen and influence methane production.
Feeding corn or legume silages, starch or soya decreases methane production when compared to grass silage. When looking at feeding alternatives, brassicas have been shown to reduce methane emissions in sheep and cattle although with differing implications for productivity. Another option investigated was the combination of maize and legume silage, which was found to reduce N wastage, providing improvements in terms of water quality and GHG emissions.

Feed supplements

Concentrate feed and starches will generally provide more digestible nutrients than roughages, which increases the digestibility of feed and generally lifts animal productivity. The sustainability of this approach (in terms of GHG mitigation) depends on the access to and availability of feed and potential competition with direct human consumption. There are a variety of cost effective lipid sources that are found in by products of industry, for example distiller’s grains, or meals from the biodiesel industry. Lipids seem to increase feed efficiency but their effect depends on feed consumption and the effect is limited on pastures. The long term effects on productivity and
product quality need further research.

Precision feeding

The area of precision feeding is all about getting the right nutrient to the right animal at the right time. Understanding an animal’s need on a daily basis can result in major resource efficiency gains. Although direct mitigation effects are uncertain and hard to predict, precision feeding
will increase feed efficiency and productivity and consequently can improve farm profitability.

Customised balanced feeding programmes in dairy cattle have been shown to be effective at increasing productivity and reducing methane emissions intensity (by between 15-20%) and also N excretion (20-30%) which results in reduced emissions from manure. Precision feeding has the greatest potential in high value systems that are already using technology on-farm.

What’s next?

Increasing animal productivity has financial benefits associated with it. In order to achieve this, knowledge and understanding of feed quality and the animals’ need is required as well as flexibility to change production systems to grow sufficient quantities and qualities of feed.

What are the barriers?

To implement precision feeding systems, investment will be needed in new technology as well as knowledge in how to run it, as well as the existence of adequate infrastructure and supply chains.

For strategies that involve using substitutes or supplements as well as system changes, new knowledge may be needed by farm managers and the impact on the whole farm and the wider supply chain of using different products will need to be monitored.

For more information and to read the report in full, please click here.