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Fuel for the Fire: Livestock Inputs and GHG Emissions

26 November 2008

The effects of livestock farming on climate change is an ever-expanding issue for the meat industry. At the forefront of consumer concerns is the emission of greenhouse gases (GHGs). Consequently, in a bid to tackle the problem, ongoing research attempts to identify where these emissions are coming from, writes Adam Anson, reporting for TheCattleSite.

The livestock industry has come under a lot of criticism in the media for having an intensive rate of greenhouse gas emissions in comparison with other food sectors. It has become apparent that this is not an issue that can be avoided and the industry will be forced to work together to reduce the current impact.


Cattle feeding at a highly intensive farm
Image: World Society for the Protection of Animals

Some consumer groups have already turned their backs on the meat industry as a whole, and many more will follow unless the industry can prove it can cut emissions. The vast majority of impacts occur at the farm stage, with subsequent processing, retailing and transport playing more minor roles. This will mean that it is the farmers themselves, who will be obliged to act the most.

It has been estimated in a report by the Food and Agriculture Organisation (FAO) that, globally, the livestock system accounts for 18 per cent of GHG emissions. At the European level, the EU commissioned report referred to earlier puts the contribution of meat and dairy products at about 13 per cent of all EU GHGs.

When discussing GHGs the majority of people tend to think in terms of carbon dioxide, (CO2), but for the livestock industry the two main gases that have the greatest detrimental effect are Nitrous Oxide (N2O) and methane(CH4) .

Although these gases are released in smaller quantities than carbon dioxide, they have far higher Global Warming Potentials (GWPs) (of 296 and 23 times higher respectively). According to a report by the World Society for the Protection of Animals, in this context, livestock production releases the equivalent of seven billion tonnes of carbon dioxide every year.

The report, entitled: Eating Our Future, explains how, on farms, carbon dioxide is released when fossil fuels are "used in fertiliser and feed grain production and when forests are converted into grazing or feed crop land". Methane is produced by digestion and manure (especially grazing animals), and nitrous oxide emissions result primarily from fertiliser and manure application.

Role of livestock in GHG emissions
Gas Contribution to climate change (%) Livestock emissions (billion tonnes carbon dioxide equivalent) Livestock emissions as % of total anthropogenic
Carbon dioxide 70 2.70 9
Methane 18 2.17 37
Nitrous oxide 9 2.19 64
Image: World Society for the Protection of Animals

A different report, Cooking Up A Storm, published by the Food Climate Research Centre (FCRC), says that N2O contributes an average of 49 per cent of the total global warming potential, and CH4 about 42 per cent – leaving a CO2 contribution of only nine per cent.

It says that global consumption of meat is forecast to double by the year 2050 if expected trends are fulfilled. On this assumption cutting emissions in the meat industry will become an even more important demand and is sure to receive the full focus of regulatory bodies.

For the livestock industry to analyse how it can come to grips with this problem, it has to understand where the problems lie. One of the the root causes lies with inputs and it has to discover what it is that it is feeding the livestock that is creating high levels of GHG emissions?'

The Unwanted Output of Inputs

The main inputs to livestock production are, broadly speaking: energy, feed (including forage), land and water. Energy input for livestock systems are quite minimal and could be solved by simple renewable energy supplies.

The obvious effects of different types of livestock feeds have been extensively researched. However, it is often the secondary effects which can be more harmful. A key concern with soy for example - a widely used feed - comes from the current biofuel boom which is acting as an opposing market to livestock feed. Consequently, oilseed price and demand is on the up. According to FCRC, this will lead to one or all of three results.

One possibility is that more land will be cleared to accommodate the additional demand which will releases stored carbon into the atmosphere. Another possibility is that "increased inputs will be applied to increase productivity", also increasing GHG emissions. The third possible alternative envisions land used for less profitable crops being over taken for oilseeds production, resulting in damages to poorer communities that rely upon them.

Cereals are a major source of nutrition for pigs, poultry, dairy cows and for beef cattle in intensive systems. The FAO calculates that globally, one-third of the cereals grown are used to feed livestock while the World Resources Institute puts the figure higher at 37 per cent. But what is the GHG ‘opportunity cost’ of using land to feed animals rather than feeding people?

The 'feed conversion efficiency' of an animal can be calculated by examining weight gained to feed consumed. The more feed is consumed, the more GHG intensive that animal may be. The implication of all this means that we can compare livestock to see how efficient they are at converting feed into meat.

According to current data broiler chickens reared in conventional farm systems, feed efficiency is high at 1.8. For eggs the conversion ratio is around two while for finishing pigs it is now 2.75. Although the feed conversion rate for beef cattle is far harder to estimate it is usually estimated somewhere between five and 10.

Regarding by-products, research by Fadel, concludes that ruminants do indeed make use of crop residues and other by-products. However, current levels of production cannot be sustained on by-products alone and there may at times be trade-offs between transport impacts and the goals of utilising by-products.

It is generally considered that livestock farms are not as efficient as crops at producing food energy. However, according to Cooking Up a Storm, not all land is good enough for arable farming and livestock tend to make use of this poorer quality land.

The report argues that there is a case to say that 'livestock rearing can be resource efficient'. However, many grasslands are not a ‘free’ resource. Lowland pastures can be heavily fertilised leading to N2O emissions, CO2 emissions will also be released during fertiliser production. The report adds that in the winter, 'dairy and beef cattle also eat grass in its fermented form as silage, the production of which requires some energy'.

The truth behind GHG emissions is a clearly complex issue and the solution is difficult to ascertain. in order to gain a better picture of the impacts of livestock production and consumption, we need to consider the inputs, the outputs and also the alternatives.

November 2008

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